Why Does My ASP.NET MVC Form Fail to Post a List of Objects?

Solving the ASP.NET MVC Form Submission Problem: Lists of Objects

ASP.NET MVC forms are essential for gathering user data, but submitting lists of objects can present a significant hurdle. The common issue: the controller receives a null list instead of the expected data.

The Root Cause: Lack of Unique Element Identification

This problem stems from poorly named form elements. When using foreach loops to create form fields, the resulting HTML elements often share identical names, lacking individual identifiers. This prevents the model binder from correctly associating the data with the objects in the list.

The Solution: EditorTemplates

The solution lies in using EditorTemplates. Creating an EditorTemplate for your PlanCompareViewModel provides strongly-typed views for each model in the list. These templates automatically generate form elements with unique names and indices, enabling the model binder to reconstruct the list correctly.

Simplifying the Parent View with EditorForModel()

In your parent view, the EditorForModel() helper simplifies the process. It automatically generates the necessary HTML using the EditorTemplate, eliminating the need for manual looping and partial views. This approach ensures proper element naming and simplifies your code.

The Benefits of Templates

Using EditorTemplates not only solves the naming issue but also significantly cleans up your parent view's code. This leads to more maintainable and efficient form handling in your MVC applications.

In Conclusion

The inability of MVC forms to correctly post lists of objects is often due to a lack of unique element identifiers. By utilizing EditorTemplates, developers can easily generate correctly named form elements, simplifying model binding and ensuring seamless data handling.

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