ASP.NET Core Binding to a dictionary

Question

In ASP.NET Core, can you bind dictionary values?

I saw in this related question in a more recent answer (not the one marked correct) it states:

In ASP.NET MVC 4, the default model binder will bind dictionaries using the typical dictionary indexer syntax property[key].

Is this also true for ASP.NET Core MVC (and/or Razor Pages)?

Just a note: Binding to dictionaries works, if you have a `Dictionary`. It will _not_ work (i.e. the value is always null) if you have a `Dictionary`. — Uwe Keim, Nov 24 '21 at 07:43

score 6 · Accepted Answer · answered Dec 29 '20 at 06:53

6

Yes it's also true for ASP.NET Core MVC (and/or Razor Pages).

You can see the following is a simple demo in asp.net core.

Class:

 public class Command
{
    [Key]
    public string ID { get; set; }
    public string Name { get; set; }
    public Dictionary<string, string> Values { get; set; }
}

Action:

 [HttpPost]
    public IActionResult Test(Command command)
    {
        return View();
    }

View:

@model Command
<form asp-action="Test">
    <input type="text" name="Id" />
    <input type="text" name="Name" />
    <input type="hidden" name="Values[0].Key" value="Apple" />
    <input type="text" name="Values[0].Value" />
    //....
    <input type="submit" value="Click" />
</form>

Result:

answered Dec 29 '20 at 06:53

Yinqiu

6,609
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14

will it allow you to reference it like this: – Dan Dec 29 '20 at 07:08
But isn't that just binding the value to a specific "element" in the dictionary? – Dan Dec 29 '20 at 07:14
You can see [here](https://i.stack.imgur.com/X3Rdp.gif). – Yinqiu Dec 29 '20 at 07:20
Sorry for misunderstood your meaning before. – Yinqiu Dec 29 '20 at 07:24
2

If you use ``,it will bind to `{[Mykey,MyValue]}` – Yinqiu Dec 29 '20 at 07:28
Just want to make sure I completely understand. If this wasn't hidden and the user changed the value to "5" and submitted the page , would the Dictionary property include a key value pair `Mykey: 5` ? – Dan Dec 29 '20 at 07:49
1

Yes.It it will be. – Yinqiu Dec 29 '20 at 07:50
1

You can see [here](https://i.stack.imgur.com/Qeanj.gif) – Yinqiu Dec 29 '20 at 07:52
1

Just a note: This works, if you have a `Dictionary`. It will _not_ work (i.e. the value is always null) if you have a `Dictionary`. – Uwe Keim Nov 24 '21 at 07:42

ASP.NET Core Binding to a dictionary

1 Answers1