Скачать или смотреть Calling Older .NET Framework DbContext in a .NET 5 Console Application

Learn how to successfully integrate your older .NET Framework `DbContext` with a modern `.NET 5` console application! This comprehensive guide will help you tackle the common pitfalls and ensure smooth functionality.
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This video is based on the question https://stackoverflow.com/q/66859320/ asked by the user 'supermanpineaplle' ( https://stackoverflow.com/u/15462297/ ) and on the answer https://stackoverflow.com/a/66862705/ provided by the user 'J Weezy' ( https://stackoverflow.com/u/4630376/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Calling Older .NET Framework DbContext in a .NET 5 Console Application: A Step-by-Step Guide

Are you trying to integrate a legacy .NET Framework 4.7 DbContext class library into your fresh .NET 5 console application? If so, you're not alone! Many developers face similar challenges when merging old code with new technologies. In this guide, we will explore a clear solution to help you leverage your existing data layer and services seamlessly.

The Problem

Your goal is to build a console application using .NET 5, while simultaneously tapping into an existing data layer developed using the older .NET Framework 4.7. You implemented a service collection to build the provider, but unfortunately, you are encountering the error:

[[See Video to Reveal this Text or Code Snippet]]

This issue arises because the DbContext constructor in your legacy application is attempting to reference the connection string line stored in the application configuration file, which is not being found in the context of your newer console application.

The Solution

To effectively integrate the older DbContext, you will need to adjust how the connection string is handled within your existing setup. Here's how to break it down:

Step 1: Update Your DbContext Constructor

In the existing DbContext class from the legacy application, change the constructor to leverage dependency injection through IConfiguration. Here's an example of what the adjusted constructor could look like:

[[See Video to Reveal this Text or Code Snippet]]

In this example:

We're pulling the connection string value directly from the IConfiguration object and supplying it to the DbContextOptionsBuilder.

This approach ensures that the connection string is correctly referenced from the appsettings.json of your .NET 5 application.

Step 2: Ensure Your appsettings.json is Correct

Make sure your appsettings.json file in the .NET 5 application has the correct format. You provided a good example, which should look like this:

[[See Video to Reveal this Text or Code Snippet]]

This JSON configuration is critical for the application to locate the connection string.

Step 3: Building the Service Provider

In your Program.cs, you have correctly set up the ServiceCollection. Ensure that the MyDbContext is being registered correctly using the new constructor:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Retrieve Your Data

Finally, you can access your data layer. Ensure that you retrieve data using the service provider, which now correctly recognizes the connection string:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Integrating legacy code with current technology can be tricky, but by following the steps outlined above, you should be able to connect your old .NET Framework DbContext to your new .NET 5 console application smoothly. Make sure to update your DbContext constructors to accept an IConfiguration which will provide the necessary connection string, and always validate your configuration file.

With these adjustments, you can breathe new life into your existing applications and enjoy the improvements brought by the newer .NET framework.

Happy coding!