How does model binding work with collections in ASP.NET MVC?

How does model binding work with collections in ASP.NET MVC?

Model binding in ASP.NET MVC allows you to map form data to your model classes. When dealing with collections, the framework expects the input names to follow a specific pattern, such as 'Items[0].Name', 'Items[1].Name', etc. This way, it can create a list of objects from the submitted data.

Can you give me an example of how to set this up in a form?

Sure! In your view, you can create a form like this:

@model YourNamespace.YourViewModel
<form asp-action="YourAction">
    @for (int i = 0; i < Model.Items.Count; i++)
    {
        <input type="text" name="Items[@i].Name" value="@Model.Items[i].Name" />
    }
    <button type="submit">Submit</button>
</form>

What happens if I don't follow the naming convention?

If you don't follow the naming convention, the model binder won't be able to correctly map the form data to your model properties. This can result in null values or errors when trying to access the collection in your action method.

Are there any limitations to model binding with collections?

Yes, there are some limitations. For instance, the model binder can struggle with complex nested collections or when the collection items have validation attributes that conflict with the binding process.