ERROR 1: PROJ: proj_create_from_database: Cannot find proj.db when using Pyinstaller

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06-10-2024

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Pyinstaller and PROJ.db: Resolving the "Cannot find proj.db" Error

The Problem: You're trying to bundle your Python application using PyInstaller, but it's throwing an error: "ERROR 1: PROJ: proj_create_from_database: Cannot find proj.db". This typically happens when your code relies on the PROJ library, a powerful tool for geospatial data projections.

Simplified: Imagine you're packing a suitcase for a trip. You have all the clothes and toiletries, but you forgot the essential map (the PROJ.db). Without it, you can't navigate the geospatial world!

The Scenario:

Let's say you have a simple Python script that uses the pyproj library for coordinate transformations:

import pyproj

def transform_coordinates(lon, lat, from_crs, to_crs):
    """Transforms coordinates from one coordinate system to another."""
    source = pyproj.Proj(init=from_crs)
    target = pyproj.Proj(init=to_crs)
    return pyproj.transform(source, target, lon, lat)

# Example usage
lon, lat = -74.0060, 40.7128
from_crs = 'epsg:4326'  # WGS 84
to_crs = 'epsg:32618'  # UTM Zone 18N
transformed_coords = transform_coordinates(lon, lat, from_crs, to_crs)
print(f"Transformed coordinates: {transformed_coords}")

When you try to package this script using PyInstaller:

pyinstaller --onefile your_script.py 

You encounter the dreaded "Cannot find proj.db" error.

Why this happens:

• Dependency Issues: PyInstaller, by default, doesn't include the proj.db file, which is part of the PROJ library. It's like forgetting the map in your luggage!
• Hidden Dependency: The pyproj library utilizes PROJ.db for its projection operations, but this dependency might not be explicitly stated during packaging.

Solutions:

1. Bundle PROJ.db:

   • Locate PROJ.db: The proj.db file is usually found in the PROJ installation directory. For example, on Linux systems, it's typically at /usr/share/proj/proj.db.

   • Add it to the Data Files: Modify your PyInstaller command to include the proj.db file:

     pyinstaller --onefile --add-data "path/to/proj.db;proj" your_script.py 
     

     This will create a proj directory in the output executable and copy the proj.db file there.

2. Include PROJ Library:

   • Install PROJ: Ensure you have the PROJ library installed on your system:

     pip install proj-bin  # Or the appropriate package manager for your OS
     

   • Use PROJ with PyInstaller: Use the --hidden-import flag to include PROJ library modules during packaging:

     pyinstaller --onefile --hidden-import=proj.database your_script.py 
     

   • Alternative: If you have multiple files from the PROJ library to include, create a separate file called hiddenimports.txt and specify the paths to those files within it. Then, use the --hidden-import=hiddenimports.txt argument with PyInstaller.

Additional Tips:

• Check for other dependencies: Your project might have other dependencies that require data files or libraries. Ensure you've properly addressed all required components for your code to function seamlessly within the packaged application.
• Virtual Environments: Using a virtual environment for your project helps maintain a clean and consistent environment for both development and packaging.

Conclusion:

Successfully packaging applications using PyInstaller requires understanding and addressing dependencies. The "Cannot find proj.db" error often points to an overlooked dependency that can be easily resolved by including the necessary data file or library during the packaging process. By following these steps, you can ensure your geospatial applications run smoothly and efficiently in their bundled form.