How do I bind to a specific array element in ASP.NET MVC?

Question

I'm using ASP.NET MVC RC1 and trying to bind a textbox to an object property like so:

<%= Html.TextBox("Comments.Contacts[0].ContactName") %>

It seems like it should work, since this does:

<%= ((MuralProject)ViewData.Model).Comments.Contacts[0].ContactName %>

But alas, the result in the textbox is an empty string. Am I doing something wrong?

John Foster · Accepted Answer · 2009-02-22 22:45:47Z

3

The first argument for the text box extension method sets the name of the input element that's eventually created and also tries to get an entry from ViewData/Model (for the model it uses TypeDescriptors / reflection) based on that argument.

The way it does this is just by splitting up the input string at the dots then checking the ViewDataDictionary for specific keys and the Model via reflection so in the case you give it'll try and look for Contacts[0] rather than Contacts and won't pick up your property.

To get around this you just need to supply the actual value of the object e.g.

Html.TextBox("Comments.Contacts[0].ContactName", 
             Model.Comments.Contacts[0].ContactName)

You can see this yourself if you look at the MVC source and take a peek at the ViewDataDictionary class.

edited Feb 22, 2009 at 22:45

answered Feb 22, 2009 at 16:36

John Foster

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2 Comments

paulwhit Over a year ago

Interesting. Without the array it seems to work with a single parameter. Thanks.

John Foster Over a year ago

Updated as to why it doesn't work with arrays, basically it's trying to find a property with the name Contacts[0] rather than Contacts and giving up

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