asp.net mvc 3 - MVC 3 field mandatory if another field is filled -

i have simple question.

i have example 2 fileds mapped on model ex: textbox_1 , textbox_2.

i whant ask if exist way (ex mandatory decorator) imposes textbox_2 mandatory if fill textbox_1. if not fill textbox_1 textbox 2 optional.

is there elegant way ?

there no out of box solution in asp.net mvc this. here attribute created solve it. there 3 available usages attribute:

• pass null targetvalue constructor: required when dependent field null.
• pass value tagetvalue: required when dependent field equals passed in value.
• pass "*" tagetvalue: required when dependent field populated.

in case need pass "*" targetvalue constructor, meaning dependent property can non null value.

note: contains both, server , client side (+ unobtrusive) validation.

server side attribute class:

public class requiredifattribute : validationattribute, iclientvalidatable {     protected requiredattribute _innerattribute;      public string dependentproperty { get; set; }     public object targetvalue { get; set; }      public bool allowemptystrings     {                 {             return _innerattribute.allowemptystrings;         }         set         {             _innerattribute.allowemptystrings = value;         }     }      public requiredifattribute(string dependentproperty, object targetvalue)     {         _innerattribute = new requiredattribute();         dependentproperty = dependentproperty;         targetvalue = targetvalue;     }      protected override validationresult isvalid(object value, validationcontext validationcontext)     {         // reference property validation depends upon         var containertype = validationcontext.objectinstance.gettype();         var field = containertype.getproperty(dependentproperty);          if (field != null)         {             // value of dependent property             var dependentvalue = field.getvalue(validationcontext.objectinstance, null);             // trim spaces of dependent value             if (dependentvalue != null && dependentvalue string)             {                 dependentvalue = (dependentvalue string).trim();                  if (!allowemptystrings && (dependentvalue string).length == 0)                 {                     dependentvalue = null;                 }             }              // compare value against target value             if ((dependentvalue == null && targetvalue == null) ||                 (dependentvalue != null && (targetvalue == "*" || dependentvalue.equals(targetvalue))))             {                 // match => means should try validating field                 if (!_innerattribute.isvalid(value))                     // validation failed - return error                     return new validationresult(formaterrormessage(validationcontext.displayname), new[] { validationcontext.membername });             }         }          return validationresult.success;     }      public virtual ienumerable<modelclientvalidationrule> getclientvalidationrules(modelmetadata metadata, controllercontext context)     {         var rule = new modelclientvalidationrule         {             errormessage = formaterrormessage(metadata.getdisplayname()),             validationtype = "requiredif",         };          string depprop = builddependentpropertyid(metadata, context viewcontext);          // find value on control depend on;         // if it's bool, format javascript style          // (the default true or false!)         string targetvalue = (targetvalue ?? "").tostring();         if (targetvalue bool)             targetvalue = targetvalue.tolower();          rule.validationparameters.add("dependentproperty", depprop);         rule.validationparameters.add("targetvalue", targetvalue);          yield return rule;     }      private string builddependentpropertyid(modelmetadata metadata, viewcontext viewcontext)     {         // build id of property         string depprop = viewcontext.viewdata.templateinfo.getfullhtmlfieldid(dependentproperty);         // unfortunately have name of current field appended beginning,         // because templateinfo's context has had fieldname appended it. instead,         // want context though 1 level higher (i.e. outside current property,         // containing object, , hence same level dependent property.         var thisfield = metadata.propertyname + "_";         if (depprop.startswith(thisfield))             // strip off again             depprop = depprop.substring(thisfield.length);         return depprop;     } } 

client side (including unobtrusive validation):

$.validator.addmethod('requiredif',     function (value, element, parameters) {         var id = '#' + parameters['dependentproperty'];          // target value (as string,          // that's actual value be)         var targetvalue = parameters['targetvalue'];         targetvalue = (targetvalue == null ? '' : targetvalue).tostring();          // actual value of target control         // note - needs cater more          // control types, e.g. radios         var control = $(id);         var controltype = control.attr('type');         var actualvalue =             controltype === 'checkbox' ?             control.attr('checked').tostring() :             control.val();          // if condition true, reuse existing          // required field validator functionality         if ($.trim(targetvalue) === $.trim(actualvalue) || ($.trim(targetvalue) === '*' && $.trim(actualvalue) !== ''))             return $.validator.methods.required.call(               this, value, element, parameters);          return true;     });  $.validator.unobtrusive.adapters.add(     'requiredif',     ['dependentproperty', 'targetvalue'],     function (options) {         options.rules['requiredif'] = {             dependentproperty: options.params['dependentproperty'],             targetvalue: options.params['targetvalue']         };         options.messages['requiredif'] = options.message;     });