How to Use LINQ to Find and Replace Values in C# Lists

Learn how to effectively use `LINQ` in C# to find and replace values in lists. This guide will take you through the process step-by-step, making it simple and clear.
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This video is based on the question https://stackoverflow.com/q/68511282/ asked by the user 'Rodrigo Loy' ( https://stackoverflow.com/u/6753964/ ) and on the answer https://stackoverflow.com/a/68511379/ provided by the user 'Emin Mesic' ( https://stackoverflow.com/u/11120774/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use LINQ to Find and Replace Values in C# Lists: A Step-by-Step Guide

When working with C# , you might find yourself needing to manipulate data retrieved from a database. One common requirement is to find specific values in your data structures and replace them with more user-friendly alternatives. Let’s walk through how to achieve this using LINQ (Language Integrated Query) in a clean and efficient way.

The Problem

You have a scenario where you're retrieving documents from a database and the status of these documents may sometimes come in a format that isn't user-friendly. For instance, you might get statuses like "PendingForApprover", but you want them displayed in a more readable format: "Pending for approver".

Previously, you used data annotations to manage this display, but since you need to format your data as JSON for server-side processing, that approach no longer suits your needs. Your challenge is how to perform the necessary replacements directly within your LINQ query.

The Solution

Using Switch Expressions

A straightforward and effective way to handle this situation is to utilize switch expressions in your LINQ query. This method allows you to define clear cases for your statuses and their corresponding string representations.

Implementation Steps

Here are the steps to implement this solution:

Identify Your Status Values: Determine the various statuses you will be working with. In this case:

Status.One

PendingForApprover

Update Your LINQ Query: Integrate the switch expression into your existing LINQ query as follows:

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

Explanation of the Code

Switch Expression Use: The key line in this snippet is where we assign Status. The switch expression allows you to define how each status should be handled:

If w.Status is Status.StatusOne, the result will be "Status One".

If it's Status.PendingForApprover, it will be "Pending for approver".

If it doesn't match either of these cases, it defaults to "Unknown".

LINQ Query Structuring: The rest of the query remains largely intact, meaning you're still leveraging LINQ for filtering and projecting the data as needed.

Benefits of This Approach

Clear Code: Using switch expressions makes your intention clear. When another developer (or you at a later time) looks at this code, it will be immediately apparent what statuses are being transformed.

Fewer Dependencies: You no longer rely on data annotations which may not serve your needs when transforming data to JSON.

Flexibility: If more statuses are added or modified, you can easily update the switch expression without overhauling your entire processing logic.

Conclusion

Manipulating data with LINQ doesn't have to be complicated. By using switch expressions, you can efficiently replace values within your queries to better serve your application's front-end needs. This method not only cleans up your code but also makes it more maintainable and understandable.

If you encounter similar challenges in your development process, consider employing LINQ with switch expressions for clear and concise data transformations.

Feel free to share your thoughts or ask questions in the comments below!

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