如何使用 C# 管理登入與驗證

使用 C# 在登入驗證後將 HTML 轉換為 PDF

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若要在 C# 環境中透過登入驗證將 HTML 轉換為 PDF,請使用 IronPDF 的 ChromeHttpLoginCredentials 進行網路驗證,或在轉換前使用 HttpClient 下載 HTML 檔案。 此方法能有效處理網路驗證與 HTML 表單登入兩種情境。

快速入門:使用 IronPDF 將 HTML 轉換為 PDF(需登入)

利用 IronPDF 的 API,將登入表單後方的 HTML 頁面轉換為 PDF 檔案。 本指南示範了 ChromeHttpLoginCredentials 用於驗證及檢索受保護的內容。 請透過簡明扼要的程式碼範例,同時處理網路驗證與 HTML 表單登入機制。

  1. using NuGet 套件管理員安裝 https://www.nuget.org/packages/IronPdf

    PM > Install-Package IronPdf
  2. 請複製並執行此程式碼片段。

    new ChromePdfRenderer { LoginCredentials = new ChromeHttpLoginCredentials("username","password") }
        .RenderUrlAsPdf("https://example.com/protected")
        .SaveAs("secure.pdf");
  3. 部署至您的生產環境進行測試

    立即透過免費試用,在您的專案中開始使用 IronPDF

    arrow pointer


處理登入驗證的最佳實務有哪些?

IronPDF 透過 ChromeHttpLoginCredentials API 支援 TLS 網路驗證(使用者名稱與密碼)。 有關各種登入情境的完整指引,請參閱 TLS 網站與系統登入教學

建議使用 System.Net.WebClientHttpClient 來下載 HTML 及相關資源。 此方法支援標題、登入及其他相關需求。 IronPDF 會將 HTML 下載至記憶體或磁碟後,再轉換為 PDF 格式。 使用 HtmlAgilityPack 提取樣式表和圖片等資源,然後使用 System.Net.WebClient 進行下載。

// Download HTML content from a URL with authentication
string html;
using (WebClient client = new WebClient()) 
{
    // Add authentication headers if needed
    client.Headers.Add("Authorization", "Bearer " + accessToken);

    // Download the HTML string
    html = client.DownloadString("http://www.example.com/protected-content");
}

// Load the HTML into an HtmlDocument for parsing
HtmlDocument doc = new HtmlDocument();        
doc.LoadHtml(html);

// Extract all image sources for downloading
foreach(HtmlNode img in doc.DocumentNode.SelectNodes("//img")) 
{
    string imgSrc = img.GetAttributeValue("src", null);
    Console.WriteLine($"Found image: {imgSrc}");

    // Download each image asset
    if (!string.IsNullOrEmpty(imgSrc))
    {
        string fileName = Path.GetFileName(imgSrc);
        client.DownloadFile(imgSrc, fileName);
    }
}

// Convert the downloaded HTML to PDF
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("authenticated-content.pdf");
// Download HTML content from a URL with authentication
string html;
using (WebClient client = new WebClient()) 
{
    // Add authentication headers if needed
    client.Headers.Add("Authorization", "Bearer " + accessToken);

    // Download the HTML string
    html = client.DownloadString("http://www.example.com/protected-content");
}

// Load the HTML into an HtmlDocument for parsing
HtmlDocument doc = new HtmlDocument();        
doc.LoadHtml(html);

// Extract all image sources for downloading
foreach(HtmlNode img in doc.DocumentNode.SelectNodes("//img")) 
{
    string imgSrc = img.GetAttributeValue("src", null);
    Console.WriteLine($"Found image: {imgSrc}");

    // Download each image asset
    if (!string.IsNullOrEmpty(imgSrc))
    {
        string fileName = Path.GetFileName(imgSrc);
        client.DownloadFile(imgSrc, fileName);
    }
}

// Convert the downloaded HTML to PDF
var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("authenticated-content.pdf");
Imports System.Net
Imports HtmlAgilityPack
Imports IronPdf

' Download HTML content from a URL with authentication
Dim html As String
Using client As New WebClient()
    ' Add authentication headers if needed
    client.Headers.Add("Authorization", "Bearer " & accessToken)

    ' Download the HTML string
    html = client.DownloadString("http://www.example.com/protected-content")
End Using

' Load the HTML into an HtmlDocument for parsing
Dim doc As New HtmlDocument()
doc.LoadHtml(html)

' Extract all image sources for downloading
For Each img As HtmlNode In doc.DocumentNode.SelectNodes("//img")
    Dim imgSrc As String = img.GetAttributeValue("src", Nothing)
    Console.WriteLine($"Found image: {imgSrc}")

    ' Download each image asset
    If Not String.IsNullOrEmpty(imgSrc) Then
        Dim fileName As String = Path.GetFileName(imgSrc)
        Using client As New WebClient()
            client.DownloadFile(imgSrc, fileName)
        End Using
    End If
Next

' Convert the downloaded HTML to PDF
Dim renderer As New ChromePdfRenderer()
Dim pdf = renderer.RenderHtmlAsPdf(html)
pdf.SaveAs("authenticated-content.pdf")
$vbLabelText   $csharpLabel

請注意使用重載的 System.Uri 建構函式,將相對網址轉換為絕對網址。 若要將 HTML 文件中的所有相對路徑轉換為絕對路徑,請使用 HtmlAgilityPack 在頁首加入 <base> 標籤。 範例。 有關處理 URL 和資源的更多資訊,請參閱《基礎 URL 與資源編碼指南》。}}

為什麼我應該先下載 HTML 內容?

在轉換前先下載 HTML 內容有以下幾項優勢:

  1. 完全控制:在轉換前修改 HTML、修復失效連結,或插入驗證憑證
  2. 資產管理:下載並快取外部資源,例如圖片、CSS 及 JavaScript 檔案
  3. 驗證靈活性:支援任何 .NET 驗證機制,包括 OAuth、JWT 憑證或自訂標頭
  4. 效能:將頻繁存取的內容快取以減輕伺服器負載
  5. 除錯:檢查實際轉換的 HTML 內容以排除問題

若涉及包含 Cookie 和會話的複雜驗證情境,請參閱《Cookie 指南》,該指南說明了 PDF 轉換過程中的驗證狀態管理。

如何處理圖片和樣式表等資源?

在轉換需驗證的網頁時,外部資源通常也需要相同的驗證。 以下是採用 HttpClient 的全面翻譯方案:

public async Task<string> DownloadAuthenticatedHtmlWithAssets(string url, string authToken)
{
    using (var client = new HttpClient())
    {
        // Set authentication header
        client.DefaultRequestHeaders.Authorization = 
            new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", authToken);

        // Download the main HTML
        string html = await client.GetStringAsync(url);

        // Parse HTML to find assets
        var doc = new HtmlDocument();
        doc.LoadHtml(html);

        // Create a base URI for resolving relative paths
        var baseUri = new Uri(url);

        // Download CSS files
        var cssLinks = doc.DocumentNode.SelectNodes("//link[@rel='stylesheet']");
        if (cssLinks != null)
        {
            foreach (var link in cssLinks)
            {
                string href = link.GetAttributeValue("href", "");
                if (!string.IsNullOrEmpty(href))
                {
                    var cssUri = new Uri(baseUri, href);
                    string cssContent = await client.GetStringAsync(cssUri);

                    // Embed CSS directly in the HTML
                    var styleNode = doc.CreateElement("style");
                    styleNode.InnerHtml = cssContent;
                    doc.DocumentNode.SelectSingleNode("//head").AppendChild(styleNode);

                    // Remove the external link
                    link.Remove();
                }
            }
        }

        // Return the modified HTML with embedded assets
        return doc.DocumentNode.OuterHtml;
    }
}
public async Task<string> DownloadAuthenticatedHtmlWithAssets(string url, string authToken)
{
    using (var client = new HttpClient())
    {
        // Set authentication header
        client.DefaultRequestHeaders.Authorization = 
            new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", authToken);

        // Download the main HTML
        string html = await client.GetStringAsync(url);

        // Parse HTML to find assets
        var doc = new HtmlDocument();
        doc.LoadHtml(html);

        // Create a base URI for resolving relative paths
        var baseUri = new Uri(url);

        // Download CSS files
        var cssLinks = doc.DocumentNode.SelectNodes("//link[@rel='stylesheet']");
        if (cssLinks != null)
        {
            foreach (var link in cssLinks)
            {
                string href = link.GetAttributeValue("href", "");
                if (!string.IsNullOrEmpty(href))
                {
                    var cssUri = new Uri(baseUri, href);
                    string cssContent = await client.GetStringAsync(cssUri);

                    // Embed CSS directly in the HTML
                    var styleNode = doc.CreateElement("style");
                    styleNode.InnerHtml = cssContent;
                    doc.DocumentNode.SelectSingleNode("//head").AppendChild(styleNode);

                    // Remove the external link
                    link.Remove();
                }
            }
        }

        // Return the modified HTML with embedded assets
        return doc.DocumentNode.OuterHtml;
    }
}
Imports System
Imports System.Net.Http
Imports System.Threading.Tasks
Imports HtmlAgilityPack

Public Class HtmlDownloader
    Public Async Function DownloadAuthenticatedHtmlWithAssets(url As String, authToken As String) As Task(Of String)
        Using client As New HttpClient()
            ' Set authentication header
            client.DefaultRequestHeaders.Authorization = New System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", authToken)

            ' Download the main HTML
            Dim html As String = Await client.GetStringAsync(url)

            ' Parse HTML to find assets
            Dim doc As New HtmlDocument()
            doc.LoadHtml(html)

            ' Create a base URI for resolving relative paths
            Dim baseUri As New Uri(url)

            ' Download CSS files
            Dim cssLinks = doc.DocumentNode.SelectNodes("//link[@rel='stylesheet']")
            If cssLinks IsNot Nothing Then
                For Each link In cssLinks
                    Dim href As String = link.GetAttributeValue("href", "")
                    If Not String.IsNullOrEmpty(href) Then
                        Dim cssUri As New Uri(baseUri, href)
                        Dim cssContent As String = Await client.GetStringAsync(cssUri)

                        ' Embed CSS directly in the HTML
                        Dim styleNode = doc.CreateElement("style")
                        styleNode.InnerHtml = cssContent
                        doc.DocumentNode.SelectSingleNode("//head").AppendChild(styleNode)

                        ' Remove the external link
                        link.Remove()
                    End If
                Next
            End If

            ' Return the modified HTML with embedded assets
            Return doc.DocumentNode.OuterHtml
        End Using
    End Function
End Class
$vbLabelText   $csharpLabel

有哪些工具有助於 HTML 解析?

HtmlAgilityPack 是 .NET 平台上最受歡迎的 HTML 解析函式庫,但也有其他替代方案:

  1. HtmlAgilityPack:最適合用於一般的 HTML 解析與處理
  2. AngleSharp:支援 CSS 選擇器的現代化、符合標準的 HTML 解析器
  3. CsQuery:專為熟悉 jQuery 的 C# 開發人員設計的 jQuery 風格語法
  4. 正規表達式:適用於簡單的資料擷取任務(不建議用於複雜的 HTML)

ChromeHttpLoginCredentials

如何使用網路驗證登入?

大多數 ASP.NET 應用程式皆支援網路驗證,其可靠性較 HTML 表單提交更高。 IronPDF 透過 ChromeHttpLoginCredentials 類別,內建支援基本、摘要及 NTLM 驗證機制。 如需進一步自訂標頭,請參閱《HTTP 請求標頭指南》。

:path=/static-assets/pdf/content-code-examples/how-to/logins-username-password.cs
using IronPdf;
using System;

ChromePdfRenderer renderer = new ChromePdfRenderer
{
    // setting login credentials to bypass basic authentication
    LoginCredentials = new ChromeHttpLoginCredentials()
    {
        NetworkUsername = "testUser",
        NetworkPassword = "testPassword"
    }
};

var uri = new Uri("http://localhost:51169/Invoice");

// Render web URL to PDF
PdfDocument pdf = renderer.RenderUrlAsPdf(uri);

// Export PDF
pdf.SaveAs("UrlToPdfExample.Pdf");
Imports IronPdf
Imports System

Private renderer As New ChromePdfRenderer With {
	.LoginCredentials = New ChromeHttpLoginCredentials() With {
		.NetworkUsername = "testUser",
		.NetworkPassword = "testPassword"
	}
}

Private uri = New Uri("http://localhost:51169/Invoice")

' Render web URL to PDF
Private pdf As PdfDocument = renderer.RenderUrlAsPdf(uri)

' Export PDF
pdf.SaveAs("UrlToPdfExample.Pdf")
$vbLabelText   $csharpLabel

為何網路驗證比表單提交更可靠?

相較於 HTML 表單提交,網路驗證具備以下幾項優勢:

  1. 標準化通訊協定:採用符合 RFC 標準的 HTTP 驗證標頭
  2. 瀏覽器整合:Chrome 渲染引擎可無縫處理驗證流程
  3. 會話管理:自動處理驗證挑戰與會話持久化
  4. 安全性:憑證透過標頭而非表單資料進行安全傳輸
  5. 相容性:可與大多數Enterprise級驗證系統配合使用 (Active Directory, LDAP)

進行網路驗證需要哪些憑證?

不同的驗證類型需要不同的憑證:

// Basic Authentication (most common)
var basicAuth = new ChromeHttpLoginCredentials
{
    NetworkUsername = "user@domain.com",
    NetworkPassword = "password123",
    AuthenticationType = ChromeHttpLoginCredentials.AuthType.Basic
};

// NTLM/Windows Authentication
var ntlmAuth = new ChromeHttpLoginCredentials
{
    NetworkUsername = "DOMAIN\\username", // Include domain
    NetworkPassword = "password123",
    AuthenticationType = ChromeHttpLoginCredentials.AuthType.Ntlm
};

// Custom authentication headers
var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.CustomHttpHeaders.Add("X-API-Key", "your-api-key");
renderer.RenderingOptions.CustomHttpHeaders.Add("Authorization", "Bearer " + jwtToken);
// Basic Authentication (most common)
var basicAuth = new ChromeHttpLoginCredentials
{
    NetworkUsername = "user@domain.com",
    NetworkPassword = "password123",
    AuthenticationType = ChromeHttpLoginCredentials.AuthType.Basic
};

// NTLM/Windows Authentication
var ntlmAuth = new ChromeHttpLoginCredentials
{
    NetworkUsername = "DOMAIN\\username", // Include domain
    NetworkPassword = "password123",
    AuthenticationType = ChromeHttpLoginCredentials.AuthType.Ntlm
};

// Custom authentication headers
var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.CustomHttpHeaders.Add("X-API-Key", "your-api-key");
renderer.RenderingOptions.CustomHttpHeaders.Add("Authorization", "Bearer " + jwtToken);
Imports System.Collections.Generic

' Basic Authentication (most common)
Dim basicAuth As New ChromeHttpLoginCredentials With {
    .NetworkUsername = "user@domain.com",
    .NetworkPassword = "password123",
    .AuthenticationType = ChromeHttpLoginCredentials.AuthType.Basic
}

' NTLM/Windows Authentication
Dim ntlmAuth As New ChromeHttpLoginCredentials With {
    .NetworkUsername = "DOMAIN\username", ' Include domain
    .NetworkPassword = "password123",
    .AuthenticationType = ChromeHttpLoginCredentials.AuthType.Ntlm
}

' Custom authentication headers
Dim renderer As New ChromePdfRenderer()
renderer.RenderingOptions.CustomHttpHeaders.Add("X-API-Key", "your-api-key")
renderer.RenderingOptions.CustomHttpHeaders.Add("Authorization", "Bearer " & jwtToken)
$vbLabelText   $csharpLabel

如何排除驗證失敗的問題?

常見的驗證問題與解決方案:

  1. 401 未授權:請檢查憑證及驗證類型
  2. 403 禁止存取:使用者已通過驗證但缺乏權限
  3. 超時錯誤:針對認證系統速度緩慢的情況,請增加 Timeout
  4. 憑證錯誤:請正確設定 TLS/SSL 設定

啟用除錯功能以診斷問題:

// Enable detailed logging
IronPdf.Logging.Logger.EnableDebugging = true;
IronPdf.Logging.Logger.LogFilePath = "IronPdf.log";
IronPdf.Logging.Logger.LoggingMode = IronPdf.Logging.Logger.LoggingModes.All;

// Test authentication
try 
{
    var pdf = renderer.RenderUrlAsPdf("https://secure.example.com");
    pdf.SaveAs("authenticated.pdf");
}
catch (Exception ex)
{
    Console.WriteLine($"Authentication failed: {ex.Message}");
    // Check IronPdf.log for detailed error information
}
// Enable detailed logging
IronPdf.Logging.Logger.EnableDebugging = true;
IronPdf.Logging.Logger.LogFilePath = "IronPdf.log";
IronPdf.Logging.Logger.LoggingMode = IronPdf.Logging.Logger.LoggingModes.All;

// Test authentication
try 
{
    var pdf = renderer.RenderUrlAsPdf("https://secure.example.com");
    pdf.SaveAs("authenticated.pdf");
}
catch (Exception ex)
{
    Console.WriteLine($"Authentication failed: {ex.Message}");
    // Check IronPdf.log for detailed error information
}
Imports IronPdf
Imports System

' Enable detailed logging
Logging.Logger.EnableDebugging = True
Logging.Logger.LogFilePath = "IronPdf.log"
Logging.Logger.LoggingMode = Logging.Logger.LoggingModes.All

' Test authentication
Try
    Dim pdf = renderer.RenderUrlAsPdf("https://secure.example.com")
    pdf.SaveAs("authenticated.pdf")
Catch ex As Exception
    Console.WriteLine($"Authentication failed: {ex.Message}")
    ' Check IronPdf.log for detailed error information
End Try
$vbLabelText   $csharpLabel

如何使用 HTML 表單登入?

若要透過向 HTML 表單傳送資料來登入,請使用 ChromeHttpLoginCredentials 類別。 請參閱 IronPDF 的 ChromeHttpLoginCredentials API

請注意以下要點:

  • 將登入資料傳送至 HTML 表單中 ACTION 屬性所指定的 URL。 請將此內容設定為 LoginFormUrlHttpLoginCredentials 屬性。 這可能與您欲渲染為 PDF 的網址不同。
  • 傳送代表 HTML 表單中每個輸入欄位和文字輸入區的資料。 名稱屬性定義了每個變數名稱(而非 ID)。
  • 部分網站會主動防範機器人登入。
// Configure form-based login
var formLogin = new ChromeHttpLoginCredentials
{
    LoginFormUrl = "https://example.com/login",
    LoginFormData = new Dictionary<string, string>
    {
        {"username", "user@example.com"},
        {"password", "securePassword123"},
        {"rememberMe", "true"},
        {"csrf_token", "abc123"} // Include any hidden fields
    }
};

var renderer = new ChromePdfRenderer
{
    LoginCredentials = formLogin,
    RenderingOptions = new ChromePdfRenderOptions
    {
        RenderDelay = 3000, // Allow time for login redirect
        EnableJavaScript = true
    }
};

// The actual page you want to convert (after login)
var pdf = renderer.RenderUrlAsPdf("https://example.com/dashboard");
pdf.SaveAs("dashboard.pdf");
// Configure form-based login
var formLogin = new ChromeHttpLoginCredentials
{
    LoginFormUrl = "https://example.com/login",
    LoginFormData = new Dictionary<string, string>
    {
        {"username", "user@example.com"},
        {"password", "securePassword123"},
        {"rememberMe", "true"},
        {"csrf_token", "abc123"} // Include any hidden fields
    }
};

var renderer = new ChromePdfRenderer
{
    LoginCredentials = formLogin,
    RenderingOptions = new ChromePdfRenderOptions
    {
        RenderDelay = 3000, // Allow time for login redirect
        EnableJavaScript = true
    }
};

// The actual page you want to convert (after login)
var pdf = renderer.RenderUrlAsPdf("https://example.com/dashboard");
pdf.SaveAs("dashboard.pdf");
Imports System.Collections.Generic

' Configure form-based login
Dim formLogin As New ChromeHttpLoginCredentials With {
    .LoginFormUrl = "https://example.com/login",
    .LoginFormData = New Dictionary(Of String, String) From {
        {"username", "user@example.com"},
        {"password", "securePassword123"},
        {"rememberMe", "true"},
        {"csrf_token", "abc123"} ' Include any hidden fields
    }
}

Dim renderer As New ChromePdfRenderer With {
    .LoginCredentials = formLogin,
    .RenderingOptions = New ChromePdfRenderOptions With {
        .RenderDelay = 3000, ' Allow time for login redirect
        .EnableJavaScript = True
    }
}

' The actual page you want to convert (after login)
Dim pdf = renderer.RenderUrlAsPdf("https://example.com/dashboard")
pdf.SaveAs("dashboard.pdf")
$vbLabelText   $csharpLabel

我需要擷取哪些表單資料?

若要透過 HTML 表單成功驗證,請擷取所有表單輸入內容:

// Use this helper method to extract form fields
public Dictionary<string, string> ExtractFormFields(string loginPageHtml)
{
    var formData = new Dictionary<string, string>();
    var doc = new HtmlDocument();
    doc.LoadHtml(loginPageHtml);

    // Find all input fields
    var inputs = doc.DocumentNode.SelectNodes("//input");
    if (inputs != null)
    {
        foreach (var input in inputs)
        {
            string name = input.GetAttributeValue("name", "");
            string value = input.GetAttributeValue("value", "");
            string type = input.GetAttributeValue("type", "text");

            if (!string.IsNullOrEmpty(name))
            {
                // Handle different input types
                switch (type.ToLower())
                {
                    case "checkbox":
                        if (input.Attributes["checked"] != null)
                            formData[name] = "on";
                        break;
                    case "radio":
                        if (input.Attributes["checked"] != null)
                            formData[name] = value;
                        break;
                    default:
                        formData[name] = value;
                        break;
                }
            }
        }
    }

    // Don't forget select elements
    var selects = doc.DocumentNode.SelectNodes("//select");
    if (selects != null)
    {
        foreach (var select in selects)
        {
            string name = select.GetAttributeValue("name", "");
            var selected = select.SelectSingleNode(".//option[@selected]");
            if (selected != null && !string.IsNullOrEmpty(name))
            {
                formData[name] = selected.GetAttributeValue("value", "");
            }
        }
    }

    return formData;
}
// Use this helper method to extract form fields
public Dictionary<string, string> ExtractFormFields(string loginPageHtml)
{
    var formData = new Dictionary<string, string>();
    var doc = new HtmlDocument();
    doc.LoadHtml(loginPageHtml);

    // Find all input fields
    var inputs = doc.DocumentNode.SelectNodes("//input");
    if (inputs != null)
    {
        foreach (var input in inputs)
        {
            string name = input.GetAttributeValue("name", "");
            string value = input.GetAttributeValue("value", "");
            string type = input.GetAttributeValue("type", "text");

            if (!string.IsNullOrEmpty(name))
            {
                // Handle different input types
                switch (type.ToLower())
                {
                    case "checkbox":
                        if (input.Attributes["checked"] != null)
                            formData[name] = "on";
                        break;
                    case "radio":
                        if (input.Attributes["checked"] != null)
                            formData[name] = value;
                        break;
                    default:
                        formData[name] = value;
                        break;
                }
            }
        }
    }

    // Don't forget select elements
    var selects = doc.DocumentNode.SelectNodes("//select");
    if (selects != null)
    {
        foreach (var select in selects)
        {
            string name = select.GetAttributeValue("name", "");
            var selected = select.SelectSingleNode(".//option[@selected]");
            if (selected != null && !string.IsNullOrEmpty(name))
            {
                formData[name] = selected.GetAttributeValue("value", "");
            }
        }
    }

    return formData;
}
Imports HtmlAgilityPack

Public Function ExtractFormFields(loginPageHtml As String) As Dictionary(Of String, String)
    Dim formData As New Dictionary(Of String, String)()
    Dim doc As New HtmlDocument()
    doc.LoadHtml(loginPageHtml)

    ' Find all input fields
    Dim inputs = doc.DocumentNode.SelectNodes("//input")
    If inputs IsNot Nothing Then
        For Each input In inputs
            Dim name As String = input.GetAttributeValue("name", "")
            Dim value As String = input.GetAttributeValue("value", "")
            Dim type As String = input.GetAttributeValue("type", "text")

            If Not String.IsNullOrEmpty(name) Then
                ' Handle different input types
                Select Case type.ToLower()
                    Case "checkbox"
                        If input.Attributes("checked") IsNot Nothing Then
                            formData(name) = "on"
                        End If
                    Case "radio"
                        If input.Attributes("checked") IsNot Nothing Then
                            formData(name) = value
                        End If
                    Case Else
                        formData(name) = value
                End Select
            End If
        Next
    End If

    ' Don't forget select elements
    Dim selects = doc.DocumentNode.SelectNodes("//select")
    If selects IsNot Nothing Then
        For Each selectNode In selects
            Dim name As String = selectNode.GetAttributeValue("name", "")
            Dim selected = selectNode.SelectSingleNode(".//option[@selected]")
            If selected IsNot Nothing AndAlso Not String.IsNullOrEmpty(name) Then
                formData(name) = selected.GetAttributeValue("value", "")
            End If
        Next
    End If

    Return formData
End Function
$vbLabelText   $csharpLabel

如何找到正確的表單提交網址?

表單的 action URL 對於成功驗證至關重要:

public string ExtractFormAction(string loginPageUrl, string loginPageHtml)
{
    var doc = new HtmlDocument();
    doc.LoadHtml(loginPageHtml);

    // Find the login form
    var form = doc.DocumentNode.SelectSingleNode("//form[contains(@action, 'login') or contains(@id, 'login') or contains(@class, 'login')]");

    if (form == null)
    {
        // Try finding any form with password field
        form = doc.DocumentNode.SelectSingleNode("//form[.//input[@type='password']]");
    }

    if (form != null)
    {
        string action = form.GetAttributeValue("action", "");

        // Resolve relative URLs
        if (!string.IsNullOrEmpty(action))
        {
            var baseUri = new Uri(loginPageUrl);
            var actionUri = new Uri(baseUri, action);
            return actionUri.ToString();
        }
    }

    // Default to the login page URL if no action found
    return loginPageUrl;
}
public string ExtractFormAction(string loginPageUrl, string loginPageHtml)
{
    var doc = new HtmlDocument();
    doc.LoadHtml(loginPageHtml);

    // Find the login form
    var form = doc.DocumentNode.SelectSingleNode("//form[contains(@action, 'login') or contains(@id, 'login') or contains(@class, 'login')]");

    if (form == null)
    {
        // Try finding any form with password field
        form = doc.DocumentNode.SelectSingleNode("//form[.//input[@type='password']]");
    }

    if (form != null)
    {
        string action = form.GetAttributeValue("action", "");

        // Resolve relative URLs
        if (!string.IsNullOrEmpty(action))
        {
            var baseUri = new Uri(loginPageUrl);
            var actionUri = new Uri(baseUri, action);
            return actionUri.ToString();
        }
    }

    // Default to the login page URL if no action found
    return loginPageUrl;
}
Imports System

Public Function ExtractFormAction(loginPageUrl As String, loginPageHtml As String) As String
    Dim doc As New HtmlDocument()
    doc.LoadHtml(loginPageHtml)

    ' Find the login form
    Dim form = doc.DocumentNode.SelectSingleNode("//form[contains(@action, 'login') or contains(@id, 'login') or contains(@class, 'login')]")

    If form Is Nothing Then
        ' Try finding any form with password field
        form = doc.DocumentNode.SelectSingleNode("//form[.//input[@type='password']]")
    End If

    If form IsNot Nothing Then
        Dim action As String = form.GetAttributeValue("action", "")

        ' Resolve relative URLs
        If Not String.IsNullOrEmpty(action) Then
            Dim baseUri As New Uri(loginPageUrl)
            Dim actionUri As New Uri(baseUri, action)
            Return actionUri.ToString()
        End If
    End If

    ' Default to the login page URL if no action found
    Return loginPageUrl
End Function
$vbLabelText   $csharpLabel

基於表單的驗證有哪些常見問題?

  1. CSRF 令牌:許多表單包含會過期的防偽造令牌
  2. JavaScript 驗證:某些表單需要執行 JavaScript
  3. 多步驟驗證:需分頁填寫的表單
  4. CAPTCHA 防護:人機驗證挑戰
  5. 會話超時:快速過期的登入會話

ViewBag TempData Html

如需完整的 HTML 轉 PDF 轉換指南(包含複雜的驗證情境),請參閱 HTML 轉 PDF 教學指南

如何處理 MVC 驗證?

以下解決方案可透過程式化方式將 .NET MVC 檢視渲染為字串,在忠實呈現檢視的同時,避開 MVC 登入機制。 此方法在 MVC CoreMVC Framework CSHTML 轉換為 PDF 時效果良好。

// Converts an MVC partial view to a string
public static string RenderPartialViewToString(this Controller controller, string viewPath, object model = null)
{
    try
    {
        // Set the model
        var context = controller.Co/ntrollerContext;
        controller.ViewData.Model = model;

        using (var sw = new StringWriter())
        {
            // Find the partial view
            var viewResult = ViewEngines.Engines.FindPartialView(context, viewPath);

            if (viewResult.View == null)
            {
                throw new Exception($"Partial view {viewPath} could not be found.");
            }

            // Create a view context
            var viewContext = new ViewContext(context, viewResult.View, context.Co/ntroller.ViewData, context.Co/ntroller.TempData, sw);

            // Render the view
            viewResult.View.Render(viewContext, sw);
            viewResult.ViewEngine.ReleaseView(context, viewResult.View);

            return sw.GetStringBuilder().ToString();
        }
    }
    catch (Exception ex)
    {
        // Return error message if there is an exception
        return ex.Message;
    }
}

// Usage in an MVC Controller
public ActionResult GeneratePdf()
{
    // Render authenticated view to string
    var model = new InvoiceViewModel { /* populate model */ };
    string html = this.RenderPartialViewToString("~/Views/Invoice/Details.cshtml", model);

    // Convert to PDF
    var renderer = new ChromePdfRenderer();
    var pdf = renderer.RenderHtmlAsPdf(html);

    // Return PDF file
    return File(pdf.BinaryData, "application/pdf", "invoice.pdf");
}
// Converts an MVC partial view to a string
public static string RenderPartialViewToString(this Controller controller, string viewPath, object model = null)
{
    try
    {
        // Set the model
        var context = controller.Co/ntrollerContext;
        controller.ViewData.Model = model;

        using (var sw = new StringWriter())
        {
            // Find the partial view
            var viewResult = ViewEngines.Engines.FindPartialView(context, viewPath);

            if (viewResult.View == null)
            {
                throw new Exception($"Partial view {viewPath} could not be found.");
            }

            // Create a view context
            var viewContext = new ViewContext(context, viewResult.View, context.Co/ntroller.ViewData, context.Co/ntroller.TempData, sw);

            // Render the view
            viewResult.View.Render(viewContext, sw);
            viewResult.ViewEngine.ReleaseView(context, viewResult.View);

            return sw.GetStringBuilder().ToString();
        }
    }
    catch (Exception ex)
    {
        // Return error message if there is an exception
        return ex.Message;
    }
}

// Usage in an MVC Controller
public ActionResult GeneratePdf()
{
    // Render authenticated view to string
    var model = new InvoiceViewModel { /* populate model */ };
    string html = this.RenderPartialViewToString("~/Views/Invoice/Details.cshtml", model);

    // Convert to PDF
    var renderer = new ChromePdfRenderer();
    var pdf = renderer.RenderHtmlAsPdf(html);

    // Return PDF file
    return File(pdf.BinaryData, "application/pdf", "invoice.pdf");
}
Imports System
Imports System.IO
Imports System.Web.Mvc
Imports IronPdf

' Converts an MVC partial view to a string
Public Module ControllerExtensions
    <System.Runtime.CompilerServices.Extension>
    Public Function RenderPartialViewToString(controller As Controller, viewPath As String, Optional model As Object = Nothing) As String
        Try
            ' Set the model
            Dim context = controller.ControllerContext
            controller.ViewData.Model = model

            Using sw As New StringWriter()
                ' Find the partial view
                Dim viewResult = ViewEngines.Engines.FindPartialView(context, viewPath)

                If viewResult.View Is Nothing Then
                    Throw New Exception($"Partial view {viewPath} could not be found.")
                End If

                ' Create a view context
                Dim viewContext As New ViewContext(context, viewResult.View, context.Controller.ViewData, context.Controller.TempData, sw)

                ' Render the view
                viewResult.View.Render(viewContext, sw)
                viewResult.ViewEngine.ReleaseView(context, viewResult.View)

                Return sw.GetStringBuilder().ToString()
            End Using
        Catch ex As Exception
            ' Return error message if there is an exception
            Return ex.Message
        End Try
    End Function
End Module

' Usage in an MVC Controller
Public Class InvoiceController
    Inherits Controller

    Public Function GeneratePdf() As ActionResult
        ' Render authenticated view to string
        Dim model As New InvoiceViewModel() ' populate model
        Dim html As String = Me.RenderPartialViewToString("~/Views/Invoice/Details.cshtml", model)

        ' Convert to PDF
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderHtmlAsPdf(html)

        ' Return PDF file
        Return File(pdf.BinaryData, "application/pdf", "invoice.pdf")
    End Function
End Class
$vbLabelText   $csharpLabel

為何要將檢視渲染為字串,而非直接轉換?

將 MVC 檢視渲染為字串具有以下幾項關鍵優勢:

  1. 驗證上下文:視圖在已驗證使用者的上下文中渲染
  2. 完整的 MVC 處理流程:所有 MVC 功能皆可正常運作,包括 UrlHelperViewBag 輔助函式
  3. 版面配置支援:母版頁與版面配置能正確呈現
  4. 模型綁定:複雜的檢視模型能無縫運作
  5. 動作篩選器:安全性與記錄篩選器會正常執行

此 MVC 解決方案有哪些優勢?

MVC 字串渲染方法提供:

  • 安全性:無需公開內部 URL 或繞過驗證機制
  • 效能:避免產生額外的 HTTP 請求
  • 一致性:輸出內容須與使用者在瀏覽器中所見完全一致
  • 靈活性:在 PDF 轉換前修改 HTML
  • 測試:輕鬆進行 HTML 生成單元測試

如何將模型傳遞至渲染視圖?

以下是一個包含複雜模型的完整範例:

public class InvoiceController : Controller
{
    private readonly IInvoiceService _invoiceService;

    public async Task<ActionResult> DownloadInvoicePdf(int invoiceId)
    {
        // Load data within authenticated context
        var invoice = await _invoiceService.GetInvoiceAsync(invoiceId);

        if (invoice == null || invoice.UserId != User.Identity.GetUserId())
        {
            return HttpNotFound();
        }

        // Create view model
        var viewModel = new InvoiceDetailsViewModel
        {
            Invoice = invoice,
            Company = await _invoiceService.GetCompanyDetailsAsync(),
            LineItems = await _invoiceService.GetLineItemsAsync(invoiceId),
            TaxDetails = await _invoiceService.GetTaxDetailsAsync(invoiceId)
        };

        // Render to HTML string
        string html = this.RenderPartialViewToString("~/Views/Invoice/DetailsPdf.cshtml", viewModel);

        // Add custom styling for PDF
        html = $@"
            <html>
            <head>
                <style>
                    body {{font-family: Arial, sans-serif;}}
                    .invoice-header {{background-color: #f0f0f0; padding: 20px;}}
                    .line-items {{width: 100%; border-collapse: collapse;}}
                    .line-items th, .line-items td {{border: 1px solid #ddd; padding: 8px;}}
                </style>
            </head>
            <body>
                {html}
            </body>
            </html>";

        // Convert to PDF with options
        var renderer = new ChromePdfRenderer
        {
            RenderingOptions = new ChromePdfRenderOptions
            {
                MarginTop = 20,
                MarginBottom = 20,
                MarginLeft = 10,
                MarginRight = 10,
                PrintHtmlBackgrounds = true
            }
        };

        var pdf = renderer.RenderHtmlAsPdf(html);

        // Add metadata
        pdf.MetaData.Author = "Invoice System";
        pdf.MetaData.Title = $"Invoice #{invoice.Number}";
        pdf.MetaData.CreationDate = DateTime.Now;

        return File(pdf.BinaryData, "application/pdf", $"Invoice-{invoice.Number}.pdf");
    }
}
public class InvoiceController : Controller
{
    private readonly IInvoiceService _invoiceService;

    public async Task<ActionResult> DownloadInvoicePdf(int invoiceId)
    {
        // Load data within authenticated context
        var invoice = await _invoiceService.GetInvoiceAsync(invoiceId);

        if (invoice == null || invoice.UserId != User.Identity.GetUserId())
        {
            return HttpNotFound();
        }

        // Create view model
        var viewModel = new InvoiceDetailsViewModel
        {
            Invoice = invoice,
            Company = await _invoiceService.GetCompanyDetailsAsync(),
            LineItems = await _invoiceService.GetLineItemsAsync(invoiceId),
            TaxDetails = await _invoiceService.GetTaxDetailsAsync(invoiceId)
        };

        // Render to HTML string
        string html = this.RenderPartialViewToString("~/Views/Invoice/DetailsPdf.cshtml", viewModel);

        // Add custom styling for PDF
        html = $@"
            <html>
            <head>
                <style>
                    body {{font-family: Arial, sans-serif;}}
                    .invoice-header {{background-color: #f0f0f0; padding: 20px;}}
                    .line-items {{width: 100%; border-collapse: collapse;}}
                    .line-items th, .line-items td {{border: 1px solid #ddd; padding: 8px;}}
                </style>
            </head>
            <body>
                {html}
            </body>
            </html>";

        // Convert to PDF with options
        var renderer = new ChromePdfRenderer
        {
            RenderingOptions = new ChromePdfRenderOptions
            {
                MarginTop = 20,
                MarginBottom = 20,
                MarginLeft = 10,
                MarginRight = 10,
                PrintHtmlBackgrounds = true
            }
        };

        var pdf = renderer.RenderHtmlAsPdf(html);

        // Add metadata
        pdf.MetaData.Author = "Invoice System";
        pdf.MetaData.Title = $"Invoice #{invoice.Number}";
        pdf.MetaData.CreationDate = DateTime.Now;

        return File(pdf.BinaryData, "application/pdf", $"Invoice-{invoice.Number}.pdf");
    }
}
Imports System.Threading.Tasks
Imports System.Web.Mvc

Public Class InvoiceController
    Inherits Controller

    Private ReadOnly _invoiceService As IInvoiceService

    Public Async Function DownloadInvoicePdf(invoiceId As Integer) As Task(Of ActionResult)
        ' Load data within authenticated context
        Dim invoice = Await _invoiceService.GetInvoiceAsync(invoiceId)

        If invoice Is Nothing OrElse invoice.UserId <> User.Identity.GetUserId() Then
            Return HttpNotFound()
        End If

        ' Create view model
        Dim viewModel As New InvoiceDetailsViewModel With {
            .Invoice = invoice,
            .Company = Await _invoiceService.GetCompanyDetailsAsync(),
            .LineItems = Await _invoiceService.GetLineItemsAsync(invoiceId),
            .TaxDetails = Await _invoiceService.GetTaxDetailsAsync(invoiceId)
        }

        ' Render to HTML string
        Dim html As String = Me.RenderPartialViewToString("~/Views/Invoice/DetailsPdf.cshtml", viewModel)

        ' Add custom styling for PDF
        html = $"
            <html>
            <head>
                <style>
                    body {{font-family: Arial, sans-serif;}}
                    .invoice-header {{background-color: #f0f0f0; padding: 20px;}}
                    .line-items {{width: 100%; border-collapse: collapse;}}
                    .line-items th, .line-items td {{border: 1px solid #ddd; padding: 8px;}}
                </style>
            </head>
            <body>
                {html}
            </body>
            </html>"

        ' Convert to PDF with options
        Dim renderer As New ChromePdfRenderer With {
            .RenderingOptions = New ChromePdfRenderOptions With {
                .MarginTop = 20,
                .MarginBottom = 20,
                .MarginLeft = 10,
                .MarginRight = 10,
                .PrintHtmlBackgrounds = True
            }
        }

        Dim pdf = renderer.RenderHtmlAsPdf(html)

        ' Add metadata
        pdf.MetaData.Author = "Invoice System"
        pdf.MetaData.Title = $"Invoice #{invoice.Number}"
        pdf.MetaData.CreationDate = DateTime.Now

        Return File(pdf.BinaryData, "application/pdf", $"Invoice-{invoice.Number}.pdf")
    End Function
End Class
$vbLabelText   $csharpLabel

在實施任何驗證解決方案之前,請確保您已正確安裝 IronPDF 並設定好授權金鑰。

準備好探索更多可能性了嗎? 請造訪我們的教學頁面:轉換 PDFRenderDelay

常見問題

當內容位於登入表單後方時,該如何將 HTML 轉換為 PDF?

IronPDF 提供多種方法,可在登入驗證環境下將 HTML 轉換為 PDF。您可以使用 ChromeHttpLoginCredentials API 進行 TLS 網路驗證,或透過 System.Net.WebClient 或 HttpClient 搭配適當的驗證標頭下載 HTML 內容,再使用 IronPDF 將其轉換為 PDF。

什麼是 ChromeHttpLoginCredentials,該如何使用它?

ChromeHttpLoginCredentials 是 IronPDF 用於處理網路驗證的 API。您可以透過在 ChromePdfRenderer 上設定 LoginCredentials 屬性並填入您的使用者名稱和密碼來使用此功能,讓 IronPDF 在將受密碼保護的 URL 渲染為 PDF 時自動進行驗證。

我能否處理基於 HTML 表單的登入功能以進行 PDF 轉換?

是的,IronPDF 支援基於 HTML 表單的登入功能。建議的做法是使用 System.Net.WebClient 或 HttpClient 來處理登入流程,下載經過驗證的 HTML 內容,然後使用 IronPDF 的 RenderHtmlAsPdf 方法將下載的 HTML 轉換為 PDF。

如何從已驗證的網頁下載 HTML 資源(例如圖片和樣式表)?

您可以使用 HtmlAgilityPack 解析下載的 HTML 並提取圖片和樣式表等資源網址。接著使用 System.Net.WebClient 透過相同的驗證標頭下載每個資源,最後使用 IronPDF 將完整的 HTML 套件轉換為 PDF。

處理驗證憑證或標頭的最佳做法是什麼?

當使用 IronPDF 並搭配驗證憑證時,請透過 HttpClient 或 WebClient 並附上驗證標頭(例如 Bearer 憑證)來下載 HTML 內容。將驗證過的 HTML 內容載入記憶體或儲存至磁碟後,即可使用 IronPDF 的 ChromePdfRenderer 將其轉換為 PDF。

是否有 MVC 登入驗證的替代方案?

是的,IronPDF 針對 MVC 登入驗證情境提供了解決方案。建議的做法是:先使用標準的 .NET HTTP 客戶端進行驗證並下載 HTML 內容,然後將已驗證的 HTML 直接傳遞給 IronPDF 的渲染引擎,而非讓 IronPDF 直接處理驗證程序。

Curtis Chau
技術撰稿人

Curtis Chau 擁有卡爾頓大學(Carleton University)的電腦科學學士學位,專精於前端開發,並精通 Node.js、TypeScript、JavaScript 及 React。他熱衷於打造直觀且美觀的用戶介面,喜歡運用現代框架,並創建結構完善、視覺上吸引人的手冊。

除了開發工作之外,Curtis 對物聯網(IoT)抱有濃厚興趣,致力於探索整合硬體與軟體的創新方法。閒暇時,他喜歡玩遊戲和開發 Discord 機器人,將對科技的熱愛與創意相結合。

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