Скачать или смотреть Transforming Raw SQL to Dynamic LINQ

Learn how to convert a raw SQL statement into a sequence of LINQ expressions using Entity Framework Core with our detailed guide.
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This video is based on the question https://stackoverflow.com/q/67775039/ asked by the user 'Zeneri' ( https://stackoverflow.com/u/15215658/ ) and on the answer https://stackoverflow.com/a/67820598/ provided by the user 'Svyatoslav Danyliv' ( https://stackoverflow.com/u/10646316/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Transforming Raw SQL to Dynamic LINQ: A Comprehensive Guide

As developers, we often find ourselves needing to perform complex database operations efficiently. With the growing popularity of Entity Framework Core, many are looking to translate traditional SQL statements into LINQ queries. However, this transition is not always straightforward. A common issue arises when executing LINQ queries that interact with dynamic properties. This guide will guide you through resolving these challenges by converting a raw SQL update statement into a more maintainable and flexible LINQ expression.

The Problem

You have a SQL statement designed to update an ItemList based on certain conditions. The original SQL code looks something like this:

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

When attempting to replicate this behavior in LINQ, you encounter an error related to query translation:

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

This indicates that the LINQ provider cannot translate the use of dynamic properties into a SQL command that it can execute against the database.

Understanding the Issue

The core of the problem lies in the dynamic property access within the LINQ statement. LINQ to Entities requires specific patterns for translation into SQL, and dynamic property access (like GetType().GetProperty()) is not one of them.

The Solution

To resolve this issue effectively, we can introduce an extension method that filters items based on the provided field dynamically, allowing us to avoid direct dynamic property access in our LINQ querying. Let's break down the solution into organized steps.

Step 1: Define the Filter Extension Method

You will create a static class with a method that allows you to filter based on an item list and a dynamic key name:

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

Step 2: Using the Extension Method

With our extension method in place, let's apply it in our update operation:

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

Conclusion

Transitioning from ExecuteSqlRaw to LINQ can enhance your code’s maintainability and readability, but it requires careful handling of dynamic properties. By implementing a filter extension method, you can effectively manage this transition and eliminate translation issues.

This solution not only provides clarity in your data operations but also leverages the power of LINQ for dynamic querying. If you're working with dynamic property names and need to update datasets, this pattern will serve as a valuable tool in your development toolkit.

Feel free to try these methods in your own projects and watch how it simplifies your data management tasks!