MVC3 Attribute validation question

问题

I'm getting odd behavior with my validation in my view.

My model has this property.

    [Display(Name = "Overflow Capacity")]
    [RegularExpression(@"[-+]?[0-9]*\.?[0-9]?[0-9]", ErrorMessage = "Number required.")]
    [Range(0,9999.99,ErrorMessage = "Value must be between 0 - 9,999.99")]
    public decimal OverFlowCapacity { get; set; }

My view has this:

<tr>
   <td>@Html.LabelFor(m=> m.OverFlowCapacity)</td>
   <td>@Html.EditorFor(m=>m.OverFlowCapacity)</td>                                               
   <td> @Html.ValidationMessageFor(model => model.OverFlowCapacity)</td>
</tr>

If I enter a value like 'ABC', I get the validation message 'Number required' If I enter a value of 999999, I get the validation message 'Value must be between 0 - 9,999.99'

Both of those messages are received when I tab off the text box as expected. When I leave the text box value empty and tab off, I get no errors, as expected.

However, when I submit, I get a validation message 'The Overflow Capacity field is required.'

I don't know where this is coming from. I've tried removing all validation attributes from the model, and still get the 'required' message. I'm at a loss.

Here are the scripts I've referenced.

I have other issues with mvcfoolproof that I may post later. I'm wondering if this isn't somehow responsible for my problems.

回答1:

What's happening to you now is the post validation is kicking in after the form has been submitted and determining that the decimal value cannot be null. Right now you are using a decimal type which is non-nullable. If you want this behavior and you want to see the validation before you submit the form then add the [Required] attribute to the property. However if you don't want this functionality and it can possibly be null, then change your type from decimal to decimal? or Nullable<decimal>.

Don't allow nulls and have the pre-submit validation:

[Display(Name = "Overflow Capacity")]
[RegularExpression(@"[-+]?[0-9]*\.?[0-9]?[0-9]", ErrorMessage = "Number required.")]
[Range(0,9999.99,ErrorMessage = "Value must be between 0 - 9,999.99")]
[Required]
public decimal OverFlowCapacity { get; set; }

Allow nulls and get rid of post-submit validation error:

[Display(Name = "Overflow Capacity")]
[RegularExpression(@"[-+]?[0-9]*\.?[0-9]?[0-9]", ErrorMessage = "Number required.")]
[Range(0,9999.99,ErrorMessage = "Value must be between 0 - 9,999.99")]
public decimal? OverFlowCapacity { get; set; }

回答2:

Since you're not marking your decimal type as nullable, MVC doesn't know what to do with the empty field you're posting back. Try this if you want to allow nulls/empty fields:

public decimal? OverFlowCapacity { get; set; }

and try this if you want it to have a pre-submit validation message requiring the field to be filled in:

[Required]
public decimal OverFlowCapacity { get; set; }

回答3:

Answers above explain Required error message quite well so i will just focus on second error message. i.e if you put 'abc' jquery tells you "Number Required". How does jquery know that this input should only accept number fields. The answer is; through unobtrusive attributes that are generated with form fields. If you inspect input field you will find something like

<input name="OverFlowCapacity" id="OverFlowCapacity" data-val-number="Number Required"..../>

so to override this default validation message you have to decorate your model with the attribute that does the exact same thing (number validation) and their you can override the validation message

[Numeric(ErrorMessage="override message")]
[Required(ErrorMessage="override Required message")]
public decimal OverFlowCapacity{get;set;}

I doubt Numeric attribute is present in DataAnnotation or mvc framework. you have to check into that. There are some useful attributes discussed and available here

来源：https://stackoverflow.com/questions/6852574/mvc3-attribute-validation-question

标签

asp.net-mvc-3

data-annotations

validation