


Why is My MVC Model Binder Failing to Populate a List of Objects from a Form?
Jan 21, 2025 pm 02:27 PMTroubleshooting MVC Model Binding Issues with Lists of Objects
This article addresses a common problem in MVC applications: failure of the model binder to correctly populate a list of objects from form data. The symptom is a null list in the controller action, despite seemingly correct form submission.
The Root Cause: Missing Indices
The core issue lies in the lack of indexing in form elements. Without indices, the model binder cannot differentiate individual elements within the list. For example, consider this scenario: the form initially contains elements without unique identifiers.
<code><!-- Incorrect: Missing indices --></code>
The Solution: Leveraging EditorTemplates
The solution involves using EditorTemplates to automatically generate correctly indexed form elements. This eliminates manual indexing and ensures proper model binding.
Implementation Steps:
-
Create an EditorTemplates Folder: Create a new folder named "EditorTemplates" within your Views folder. This folder should reside within the same directory as your other view files.
-
Create a Strongly-Typed View: Inside the EditorTemplates folder, create a strongly-typed view file whose name matches your model class (e.g.,
PlanCompareViewModel.cshtml
). -
Migrate Partial View Content: Move the HTML content from your original partial view into this newly created EditorTemplate.
-
Utilize
EditorForModel()
: Modify your parent view to use theEditorForModel()
helper method. This helper will automatically render the form elements, correctly indexed, based on your model.
@model IEnumerable<plancompareviewmodel> @using (Html.BeginForm("ComparePlans", "Plans", FormMethod.Post, new { id = "compareForm" })) { <div> @Html.EditorForModel() </div> }
By employing this approach, the model binder will correctly interpret and populate the list of objects in your controller action. The EditorForModel()
helper dynamically generates the necessary indices for each element, resolving the binding issue.
The above is the detailed content of Why is My MVC Model Binder Failing to Populate a List of Objects from a Form?. For more information, please follow other related articles on the PHP Chinese website!

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