JS总是返回一个空模型

Question

Model:

public class TestModel
{
    public string SomeString { get; set; }
}

View:

@model MyProject.ViewModels.TestModel

<script>
    function Test()
    {
        var modelDataJSON = '@Html.Raw(Json.Encode(Model))';
        alert(modelDataJSON);
    }
</script>

@{Model.SomeString = "asdf";}

<button type="button" onclick="Test()">Test</button>

JS alert always return JSON where all fields are set to null: {"SomeString:null}

Answer 1

That's normal behaviour...you should change the value before the script block like below...

@{Model.SomeString = "asdf";}

<script>
    function Test()
    {
        var modelDataJSON = '@Html.Raw(Json.Encode(Model))';
        alert(modelDataJSON);
    }
</script>

What happens is that before the page is rendered, Razor will resolve all the "symbols and expressions" specified in the view, so, this line...

var modelDataJSON = '@Html.Raw(Json.Encode(Model))';

will be replaced with the actual value of the model before the page gets sent to the browser...

var modelDataJSON = '{"SomeString":null}';

However, if you change the value before the the script block Razor will replace the expression with the current value. You can easily see this by viewing the page source on your browser how the value gets replaced with a "hard-coded" string