Скачать или смотреть How to Pass List of Objects from View to Controller in ASP.NET MVC

Learn how to correctly pass a list of objects back from the view to the controller in ASP.NET MVC for seamless data handling.
---
This video is based on the question https://stackoverflow.com/q/63943352/ asked by the user 'jafar' ( https://stackoverflow.com/u/5463478/ ) and on the answer https://stackoverflow.com/a/63943431/ provided by the user 'David Liang' ( https://stackoverflow.com/u/2410655/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: how to pass list of object from view to controller in asp.net mvc

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Pass List of Objects from View to Controller in ASP.NET MVC

In the world of ASP.NET MVC, there's a common challenge developers face when trying to pass a list of objects from the view back to the controller after making edits. Many developers start off by successfully displaying a list of items, but struggle when they attempt to send the updated data back. Let's take a closer look at how to solve this problem.

The Problem at Hand

Imagine you have a settings feature that allows users to modify various settings in your application. You fetch a list of settings from the database and display them on a page. After making changes, you want to send this updated list back to the server. However, this process can fail if the setup isn't done correctly, especially when it comes to the IDs and Names of the form inputs.

You might see your controller action receiving a null list, resulting in frustration. So, how can we overcome this issue?

The Correct Approach: Using a Standard For Loop

Why Not Use @ foreach?

A common mistake is to use a @ foreach loop in your Razor view to iterate through your model. The problem here is that using @ foreach creates input elements with the same IDs and Names. This is because HTML does not support multiple elements with the same name when submitting forms, leading to data mishaps.

Solution: Implementing a Standard For Loop

Instead of the @ foreach loop, you should use a standard for loop to ensure that each input element gets a unique name based on its index. This is crucial for ASP.NET MVC to bind the incoming data correctly.

Here’s how you can modify your view:

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

Breakdown of the Code:

Indexing: By using Model[i], you differentiate each item in the model. This means each input field now has a unique identifier.

Hidden Field: We are using @ Html.HiddenFor(m => m[i].Id) to maintain the unique identifier for each setting so that it can be correctly updated in the database.

EditorFor: The same principle applies when using the @ Html.EditorFor method for editing text inputs.

Handling the Post Request

Once your view is set up correctly, make sure your controller's action method looks something like this:

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

Important Notes:

Validation Check: Always check if settings is not null to avoid exceptions.

Database Entry: When calling db.Entry(settings);, ensure you handle each entry correctly, as it might require you to iterate through the collection depending on your update logic.

Conclusion

Passing a list of objects from your view to controller in ASP.NET MVC can be straightforward if you use a standard for loop instead of a @ foreach loop. By ensuring that your input fields are uniquely named, you create a smooth data flow between the client and the server.

Take note of these adjustments in your ASP.NET MVC projects, and you'll find that managing collections of objects in views and controllers becomes a lot easier.

If you have further questions or need any more tips on ASP.NET MVC development, feel free to reach out!