Use of require_from_group from jquery-validation team:
jQuery-validation project has a sub-folder in src folder called additional.
You can check it here.
In that folder we have a lot of additional validation methods that are not common that is why they're not added by default.
As you see in that folder it exists so many methods that you need to choose by picking which validation method you actually need.
Based on your question, the validation method you need is named require_from_group from additional folder.
Just download this associated file which is located here and put it into your Scripts application folder.
The documentation of this method explains this:
Lets you say "at least X inputs that match selector Y must be filled."
The end result is that neither of these inputs:
...will validate unless at least one of them is filled.
partnumber: {require_from_group: [1,".productinfo"]},
description: {require_from_group: [1,".productinfo"]}
options[0]: number of fields that must be filled in the group
options2: CSS selector that defines the group of conditionally required fields
Why you need to choose this implementation :
This validation method is generic and works for every input (text, checkbox, radio etc), textarea and select. This method also let you specify the minimum number of required inputs that need to be filled e.g
partnumber: {require_from_group: [2,".productinfo"]},
category: {require_from_group: [2,".productinfo"]},
description: {require_from_group: [2,".productinfo"]}
I created two classes RequireFromGroupAttribute and RequireFromGroupFieldAttribute that will help you on both server-side and client-side validations
RequireFromGroupAttribute class definition
RequireFromGroupAttribute only derives from Attribute. The class is use just for configuration e.g. setting the number of fields that need to be filled for the validation. You need to provide to this class the CSS selector class that will be used by the validation method to get all elements on the same group. Because the default number of required fields is 1 then this attribute is only used to decorate your model if the minimum requirement in the spcefied group is greater than the default number.
[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
public class RequireFromGroupAttribute : Attribute
{
public const short DefaultNumber = 1;
public string Selector { get; set; }
public short Number { get; set; }
public RequireFromGroupAttribute(string selector)
{
this.Selector = selector;
this.Number = DefaultNumber;
}
public static short GetNumberOfRequiredFields(Type type, string selector)
{
var requiredFromGroupAttribute = type.GetCustomAttributes<RequireFromGroupAttribute>().SingleOrDefault(a => a.Selector == selector);
return requiredFromGroupAttribute?.Number ?? DefaultNumber;
}
}
RequireFromGroupFieldAttribute class definition
RequireFromGroupFieldAttribute which derives from ValidationAttribute and implements IClientValidatable. You need to use this class on each property in your model that participates to your group validation. You must pass the css selector class.
[AttributeUsage(AttributeTargets.Property)]
public class RequireFromGroupFieldAttribute : ValidationAttribute, IClientValidatable
{
public string Selector { get; }
public bool IncludeOthersFieldName { get; set; }
public RequireFromGroupFieldAttribute(string selector)
: base("Please fill at least {0} of these fields")
{
this.Selector = selector;
this.IncludeOthersFieldName = true;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var properties = this.GetInvolvedProperties(validationContext.ObjectType); ;
var numberOfRequiredFields = RequireFromGroupAttribute.GetNumberOfRequiredFields(validationContext.ObjectType, this.Selector);
var values = new List<object> { value };
var otherPropertiesValues = properties.Where(p => p.Key.Name != validationContext.MemberName)
.Select(p => p.Key.GetValue(validationContext.ObjectInstance));
values.AddRange(otherPropertiesValues);
if (values.Count(s => !string.IsNullOrWhiteSpace(Convert.ToString(s))) >= numberOfRequiredFields)
{
return ValidationResult.Success;
}
return new ValidationResult(this.GetErrorMessage(numberOfRequiredFields, properties.Values), new List<string> { validationContext.MemberName });
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var properties = this.GetInvolvedProperties(metadata.ContainerType);
var numberOfRequiredFields = RequireFromGroupAttribute.GetNumberOfRequiredFields(metadata.ContainerType, this.Selector);
var rule = new ModelClientValidationRule
{
ValidationType = "requirefromgroup",
ErrorMessage = this.GetErrorMessage(numberOfRequiredFields, properties.Values)
};
rule.ValidationParameters.Add("number", numberOfRequiredFields);
rule.ValidationParameters.Add("selector", this.Selector);
yield return rule;
}
private Dictionary<PropertyInfo, string> GetInvolvedProperties(Type type)
{
return type.GetProperties()
.Where(p => p.IsDefined(typeof(RequireFromGroupFieldAttribute)) &&
p.GetCustomAttribute<RequireFromGroupFieldAttribute>().Selector == this.Selector)
.ToDictionary(p => p, p => p.IsDefined(typeof(DisplayAttribute)) ? p.GetCustomAttribute<DisplayAttribute>().Name : p.Name);
}
private string GetErrorMessage(int numberOfRequiredFields, IEnumerable<string> properties)
{
var errorMessage = string.Format(this.ErrorMessageString, numberOfRequiredFields);
if (this.IncludeOthersFieldName)
{
errorMessage += ": " + string.Join(", ", properties);
}
return errorMessage;
}
}
How to use it in your view model?
In your model here is how to use it :
public class SomeViewModel
{
internal const string GroupOne = "Group1";
internal const string GroupTwo = "Group2";
[RequireFromGroupField(GroupOne)]
public bool IsA { get; set; }
[RequireFromGroupField(GroupOne)]
public bool IsB { get; set; }
[RequireFromGroupField(GroupOne)]
public bool IsC { get; set; }
//... other properties
[RequireFromGroupField(GroupTwo)]
public bool IsY { get; set; }
[RequireFromGroupField(GroupTwo)]
public bool IsZ { get; set; }
}
By default you don't need to decorate your model with RequireFromGroupAttribute because the default number of required fields is 1. But if you want a number of required fields to be different to 1 you can do the following :
[RequireFromGroup(GroupOne, Number = 2)]
public class SomeViewModel
{
//...
}
How to use it in your view code?
@model SomeViewModel
<script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/require_from_group.js")" type="text/javascript"></script>
@using (Html.BeginForm())
{
@Html.CheckBoxFor(x => x.IsA, new { @class="Group1"})<span>A</span>
@Html.ValidationMessageFor(x => x.IsA)
<br />
@Html.CheckBoxFor(x => x.IsB, new { @class = "Group1" }) <span>B</span><br />
@Html.CheckBoxFor(x => x.IsC, new { @class = "Group1" }) <span>C</span><br />
@Html.CheckBoxFor(x => x.IsY, new { @class = "Group2" }) <span>Y</span>
@Html.ValidationMessageFor(x => x.IsY)
<br />
@Html.CheckBoxFor(x => x.IsZ, new { @class = "Group2" })<span>Z</span><br />
<input type="submit" value="OK" />
}
Notice the group selector you specified when using RequireFromGroupField attribute is use in your view by specifing it as a class in each input involved in your groups.
That is all for the server side validation.
Let's talk about the client side validation.
If you check the GetClientValidationRules implementation in RequireFromGroupFieldAttribute class you will see I'm using the string requirefromgroup and not require_from_group as the name of method for the ValidationType property. That is because ASP.Net MVC only allows the name of the validation type to contain alphanumeric char and must not start with a number. So you need to add the following javascript :
$.validator.unobtrusive.adapters.add("requirefromgroup", ["number", "selector"], function (options) {
options.rules["require_from_group"] = [options.params.number, options.params.selector];
options.messages["require_from_group"] = options.message;
});
The javascript part is really simple because in the implementation of the adaptater function we just delegate the validation to the correct require_from_group method.
Because it works with every type of input, textarea and select elements, I may think this way is more generic.
Hope that helps!
