psycopg2 (How It Works For Developers)

The psycopg2 library is a popular PostgreSQL database adapter for Python programming language. It is known for its efficiency, thread safety, and complete implementation of the Python DB API 2.0 specification. Let's explore its features and see some code examples. Later in this article, we will learn about IronPDF, a PDF generation library from Iron Software.

Introduction

Psycopg2 is designed to be efficient and secure, making it suitable for heavily multi-threaded applications. Some of its key features include:

• Thread Safety: Multiple threads can share the same connection—the ability to handle multi-threaded applications that create and destroy lots of cursors.
• Client-Side and Server-Side Cursors: Efficiently handle large datasets.
• Asynchronous Communication and Notifications: Support for asynchronous operations.
• COPY Support: Efficiently bulk load data using COPY TO and COPY FROM.
• Adaptation System: Automatically adapt Python types to PostgreSQL types; the package automatically transponds to the matching Postgresql data types.
• Unicode and Python 3 Friendly: Full support for Unicode and Python 3.

Installation

You can install psycopg2 using pip:

pip install psycopg2

Alternatively, you can use setup.py from the source package locally. You can obtain the source package from the source code repository here:

python setup.py build
sudo python setup.py install

python setup.py build
sudo python setup.py install

For a stand-alone package that doesn't require a compiler or external libraries, you can use the psycopg2-binary package:

pip install psycopg2-binary

Basic Usage

Here's a simple example to get you started with psycopg2.

Connecting to a Database

First, you'll need to connect to your PostgreSQL database:

import psycopg2
# Connect to your PostgreSQL database
conn = psycopg2.connect(
    dbname="your_dbname",
    user="your_username",
    password="your_password",
    host="your_host",
    port="your_port"
)
# Create a cursor object
cur = conn.cursor()

import psycopg2
# Connect to your PostgreSQL database
conn = psycopg2.connect(
    dbname="your_dbname",
    user="your_username",
    password="your_password",
    host="your_host",
    port="your_port"
)
# Create a cursor object
cur = conn.cursor()

Executing Queries

You can execute SQL queries using the cursor object:

# Execute a query
cur.execute("SELECT * FROM your_table")
# Fetch all results
rows = cur.fetchall()
# Print the results
for row in rows:
    print(row)

# Execute a query
cur.execute("SELECT * FROM your_table")
# Fetch all results
rows = cur.fetchall()
# Print the results
for row in rows:
    print(row)

Inserting Data

Here's how to insert data into a table:

# Insert data into a table
cur.execute(
    "INSERT INTO your_table (column1, column2) VALUES (%s, %s)",
    ("value1", "value2")
)
# Commit the transaction
conn.commit()

# Insert data into a table
cur.execute(
    "INSERT INTO your_table (column1, column2) VALUES (%s, %s)",
    ("value1", "value2")
)
# Commit the transaction
conn.commit()

Closing the Connection

Don't forget to close the cursor and connection when you're done:

# Close the cursor and connection
cur.close()
conn.close()

# Close the cursor and connection
cur.close()
conn.close()

Advanced Features

Using COPY for Bulk Loading

The COPY command is helpful for bulk-loading data:

# Use COPY to load data from a file
with open('data.csv', 'r') as f:
    cur.copy_from(f, 'your_table', sep=',')
conn.commit()

# Use COPY to load data from a file
with open('data.csv', 'r') as f:
    cur.copy_from(f, 'your_table', sep=',')
conn.commit()

Asynchronous Notifications

You can listen for asynchronous notifications from the database:

# Listen for notifications
cur.execute("LISTEN your_channel")
# Wait for a notification
conn.poll()
while conn.notifies:
    notify = conn.notifies.pop(0)
    print("Got NOTIFY:", notify.payload)

# Listen for notifications
cur.execute("LISTEN your_channel")
# Wait for a notification
conn.poll()
while conn.notifies:
    notify = conn.notifies.pop(0)
    print("Got NOTIFY:", notify.payload)

Introducing IronPDF

IronPDF is a powerful Python library designed to create, edit, and sign PDFs using HTML, CSS, images, and JavaScript. It offers commercial-grade performance with a low memory footprint. Key features include:

HTML to PDF Conversion:

Convert HTML files, HTML strings, and URLs to PDFs. For example, render a webpage as a PDF using the Chrome PDF renderer.

Cross-Platform Support:

Compatible with various .NET platforms, including .NET Core, .NET Standard, and .NET Framework. It supports Windows, Linux, and macOS.

Editing and Signing:

Set properties, add security with passwords and permissions, and apply digital signatures to your PDFs.

Page Templates and Settings:

Customize PDFs with headers, footers, page numbers, and adjustable margins. Supports responsive layouts and custom paper sizes.

Standards Compliance:

Adheres to PDF standards such as PDF/A and PDF/UA. It supports UTF-8 character encoding and handles assets like images, CSS, and fonts.

Generate PDF Documents using IronPDF and psycopg2

import psycopg2
from ironpdf import * 
# Apply your license key
License.LicenseKey = "Key"
# Connect to your local PostgreSQL database
conn = psycopg2.connect(
    dbname="demo",
    user="postgres",
    password="postgres",
    host="localhost",
    port="5432"
)
# Create a cursor object
cur = conn.cursor()
cur.execute('''
    CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY,
        name TEXT NOT NULL,
        age INTEGER
    )
''')
# Commit the transaction with connection object
conn.commit()
# Define the SQL statement for inserting data into the table
insert_query = '''
    INSERT INTO users (id, name, age)
    VALUES (%s, %s,%s)
'''
# Data to be inserted
userData1 = (1, 'John', 25)
# Execute the SQL command to insert data
cur.execute(insert_query, userData1)
# Data to be inserted
userData2 = (2, 'Smith', 35)
# Execute the SQL command to insert data
cur.execute(insert_query, userData2)
# Data to be inserted
userData3 = (3, 'Tom', 29)
# Execute the SQL command to insert data
cur.execute(insert_query, userData3)
# Commit the transaction
conn.commit()
# Execute a query
cur.execute("SELECT * FROM users")
# Fetch all results
rows = cur.fetchall() 
renderer = ChromePdfRenderer()
# Create a PDF from a HTML string using Python
content = "<h1>Awesome Iron PDF with psycopg2</h1>"
content += "<p>table data</p>"
for row in rows:
    print(row)
    content += "<p>"+str(row)+"</p>"
# Close the cursor and connection
cur.close()
conn.close()
pdf = renderer.RenderHtmlAsPdf(content)
    # Export to a file or Stream
pdf.SaveAs("Demopsycopg2.pdf")

import psycopg2
from ironpdf import * 
# Apply your license key
License.LicenseKey = "Key"
# Connect to your local PostgreSQL database
conn = psycopg2.connect(
    dbname="demo",
    user="postgres",
    password="postgres",
    host="localhost",
    port="5432"
)
# Create a cursor object
cur = conn.cursor()
cur.execute('''
    CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY,
        name TEXT NOT NULL,
        age INTEGER
    )
''')
# Commit the transaction with connection object
conn.commit()
# Define the SQL statement for inserting data into the table
insert_query = '''
    INSERT INTO users (id, name, age)
    VALUES (%s, %s,%s)
'''
# Data to be inserted
userData1 = (1, 'John', 25)
# Execute the SQL command to insert data
cur.execute(insert_query, userData1)
# Data to be inserted
userData2 = (2, 'Smith', 35)
# Execute the SQL command to insert data
cur.execute(insert_query, userData2)
# Data to be inserted
userData3 = (3, 'Tom', 29)
# Execute the SQL command to insert data
cur.execute(insert_query, userData3)
# Commit the transaction
conn.commit()
# Execute a query
cur.execute("SELECT * FROM users")
# Fetch all results
rows = cur.fetchall() 
renderer = ChromePdfRenderer()
# Create a PDF from a HTML string using Python
content = "<h1>Awesome Iron PDF with psycopg2</h1>"
content += "<p>table data</p>"
for row in rows:
    print(row)
    content += "<p>"+str(row)+"</p>"
# Close the cursor and connection
cur.close()
conn.close()
pdf = renderer.RenderHtmlAsPdf(content)
    # Export to a file or Stream
pdf.SaveAs("Demopsycopg2.pdf")

Code Explanation

The script demonstrates interaction with a PostgreSQL database using `psycopg2`, data manipulation (creation, insertion, retrieval), and integration with `IronPDF` for document generation.

1. Database Connection: Connects to a local PostgreSQL database named "demo" using `psycopg2`, specifying credentials for user authentication and database host details.
2. Table Creation: Defines and executes a SQL statement to create a table named `users` if it doesn't already exist. The table has columns `id` (integer, primary key), `name` (text, not null), and `age` (integer).
3. Data Insertion: Inserts three rows of data into the `users` table using parameterized queries (`userData1`, `userData2`, `userData3`). Each tuple contains values for `id`, `name`, and `age`.
4. Transaction Management: Commits the transaction after table creation and data insertion to ensure changes are saved in the database.

5. Data Retrieval: Executes a SELECT query to fetch all rows (`SELECT * FROM users`) from the `users` table and retrieves the results (`rows`).

6. PDF Generation: Uses `IronPDF` to generate a PDF document from HTML content. The HTML content includes a title and a formatted representation of the fetched data from the `users` table.
7. File Saving: Saves the generated PDF document as "Demopsycopg2.pdf" in the current directory.
8. Connection Closing: This function closes the database cursor (`cur`) and the database connection (`conn`) to release resources and ensure proper cleanup.

For exception handling, you could wrap the script around a try-catch block to ensure all error operations are handled in the event one of the queries fails or the connection fails.

Output

PDF

IronPDF License

IronPDF runs on the Python license key. IronPDF for Python offers a free trial license key to allow users to test its extensive features before purchasing.

Place the License Key at the start of the script before using IronPDF package:

from ironpdf import * 
# Apply your license key
License.LicenseKey = "key"

from ironpdf import * 
# Apply your license key
License.LicenseKey = "key"

Conclusion

Psycopg2 is a powerful and flexible library for interacting with PostgreSQL databases in Python. Its comprehensive feature set and efficient design make it an excellent choice for simple and complex database operations. IronPDF is a robust Python package and library that facilitates the creation, manipulation, and rendering of PDF documents directly from Python applications. It offers comprehensive features for generating PDFs from HTML content, integrating seamlessly with existing web technologies. With IronPDF, developers can efficiently automate generating reports, invoices, and other documentation, enhancing productivity and user experience. Its capabilities include interactive PDF forms, text extraction, merging and splitting PDFs, and the addition of security features like password protection. IronPDF's versatility and ease of use make it a valuable tool for developers looking to implement PDF generation and manipulation functionalities in their Python projects.