Validation before posting ASP.NET MVC form

Question

I have this :

@using (Html.BeginForm("Action", "Controller", FormMethod.Post))
{
@Html.TextBoxFor(m => m.City, new { id = "tbCity", maxlength = 50 })
<input type="submit" value="Save" class="btSave" />
}

I'd like do a sublit make some validation (check if "tbCity" as a length != 0), I created a function with all validation, how can I call here ? and cancel if the validation is not correct ?

Thanks,

Update1

@Adam Pope : Imagine, I have a datalodel names "Person"s (firstname, lastname, ...), a model class with public Person Person{ get; set; }, where use the [Required] attribute ?

Adam Pope · Accepted Answer · 2011-04-26 10:22:55Z

2

If you are using ASP.NET MVC 2 or 3 then you should checkout DataAnnotations

http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx
http://www.asp.net/mvc/tutorials/creating-a-mvc-3-application-with-razor-and-unobtrusive-javascript

They let you specify your validation constraints on your Domain Model and have the UI automatically generate the validation code for you.

In this case you might have a model

public class MyModel
{
    [Required]
    public string City { get; set; }
}

then your view uses that model

@model MyModel

@Html.TextBoxFor(x => x.City)
@Html.ValidationMessageFor(x => x.City)

Update

For a drop-down, I tend to do the following, not 100% sure it's optimal but it works

public class MyModel
{ 
    [Range(1,int.MaxValue,ErrorMessage="Please select a value")]
    public int OtherModelID { get; set; }

    public IList<OtherModel> OtherModels {get; set; }
}

then in the view

@model MyModel

<select id="OtherModelID" name="OtherModelID">
    <option value="0">Please Select</option>
    @foreach(var m in Model.OtherModel)
    {
        <option value="m.ID">m.Name</option>
    }
</select>

You can put a condition in there to select the current value as well if you're on an edit screen.

edited Apr 26, 2011 at 10:22

answered Apr 26, 2011 at 10:02

Adam Pope

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2 Comments

TheBoubou Over a year ago

Nice, for a Dropdown, I'd like has contraint value selected != 0, possible ?

Adam Pope Over a year ago

The [Required] attribute should go on the model class properties. So you'd have [Required] public string FirstName {get;set;}

neeebzz · Accepted Answer · 2011-04-26 09:51:00Z

1

If you are using jQuery, then you should be using a built-in framework like jQuery validation.

It might sound a little bit over-kill for your scenario but validation rules explode very easily as the project grows. So it's great to use a validation framework. jQuery validate plug-in is widely used and immensely useful.

EDIT:

Code:

$("form").live("submit", function () { 

if ($("#tbCity").val().length == 0) { 
alert("tbCity length should be greater than 0"); return false; 
}

});

edited Apr 26, 2011 at 9:51

answered Apr 26, 2011 at 9:38

neeebzz

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2 Comments

TheBoubou Over a year ago

I'd like something quick, easy and I know because not a lo of time

RYFN Over a year ago

what do you do if they have javascript disabled? how would you define this functionality on the server side for .NET MVC?

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