MVC5中的多个验证要求

Question

I have this form class 'Value' which is used multiple times, the 'Maximum' field is only used in certain instances. I need to validate that 'Maximum' has a value if the 'Show' property is true AND the 'Maximum' field is displayed. Thanks in advance!

Model:

public class Value
{
    public bool Show { get; set; }
    public bool Required { get; set; }
    [RequiredIf("Show", Domain.Comparison.IsEqualTo, true, ErrorMessageResourceType = typeof(Resources.ErrorMessages), ErrorMessageResourceName = "AuthorLabelIsRequired")]
    public string Label { get; set; }
    public string Description { get; set; }
    [RequiredIf("Show", Domain.Comparison.IsEqualTo, true, ErrorMessageResourceType = typeof(Resources.ErrorMessages), ErrorMessageResourceName = "AuthorLabelIsRequired")]
    public int? Maximum { get; set; }
} 

HTML:

<tr>
                    <td>@Html.EnumString(Model.Data.DateSection.Key)</td>
                    <td>@Html.CheckBoxFor(m => m.Data.DateSection.Value.Show)</td>
                    <td>@Html.CheckBoxFor(m => m.Data.DateSection.Value.Required)</td>
                    <td>
                        @Html.TextBoxFor(m => m.Data.DateSection.Value.Label, new { @class = "form-control" })
                        @Html.ValidationMessageFor(m => m.Data.DateSection.Value.Label)
                    </td>
                    <td>@Html.TextBoxFor(m => m.Data.DateSection.Value.Description, new { @class = "form-control" })</td>
                    <td></td>
                </tr>
                <tr>
                    <td>@Html.EnumString(Model.Data.DescriptionSection.Key)</td>
                    <td>@Html.CheckBoxFor(m => m.Data.DescriptionSection.Value.Show)</td>
                    <td>@Html.CheckBoxFor(m => m.Data.DescriptionSection.Value.Required)</td>
                    <td>
                        @Html.TextBoxFor(m => m.Data.DescriptionSection.Value.Label, new { @class = "form-control" })
                        @Html.ValidationMessageFor(m => m.Data.DescriptionSection.Value.Label)
                    </td>
                    <td>@Html.TextBoxFor(m => m.Data.DescriptionSection.Value.Description, new { @class = "form-control" })</td>
                    <td>
                        @Html.TextBoxFor(m => m.Data.DescriptionSection.Value.Maximum, new { @class = "form-control" })
                        @Html.ValidationMessageFor(m => m.Data.DescriptionSection.Value.Maximum)
                    </td>
                </tr>

Answer 1

There's actually a rather elegant way to handle conditional validation in ASP.NET MVC. Your model would end up looking something like this:

public class Value : IValidatableObject {
    public bool Show { get; set; }
    public bool Required { get; set; }
    [RequiredIf("Show", Domain.Comparison.IsEqualTo, true, ErrorMessageResourceType = typeof(Resources.ErrorMessages), ErrorMessageResourceName = "AuthorLabelIsRequired")]
    public string Label { get; set; }
    public string Description { get; set; }
    [RequiredIf("Show", Domain.Comparison.IsEqualTo, true, ErrorMessageResourceType = typeof(Resources.ErrorMessages), ErrorMessageResourceName = "AuthorLabelIsRequired")]
    public int? Maximum { get; set; }

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) {
        if (this.Show && !this.Maximum.HasValue) {
            yield return new ValidationResult("You must specify a maximum value");
        }
    }
}

Notice how the model:

1. Implements IValidateableObject
2. Has a method named Validate which returns the type IEnumerable<ValidationResult>

During the model binding process this method will automatically be called and if a validation result is returned your ModelState will no longer be valid. So using this familiar code in your controller will make sure you don't take any action unless your custom conditions check out:

public class SomeController {
    public ActionResult SomeAction() {
        if (ModelState.IsValid) {
            //Do your stuff!
        }
    }
}