User Contributed Rules

###Please feel free to contribute your own Custom Rules!###

####Example Rule####

ko.validation.rules['exampleRule'] = {
    validator: function(val, otherVal){
        /* awesome logic */
    },
    message: 'Sorry Chief, {0} this is not Valid'
};

####Requires one of more (in array)####

/*
 * This rules checks the given array of objects/observables and returns 
 * true if at least one of the elements validates agains the the default
 * 'required' rules
 * 
 * Example:
 * 
 *
 * self.mobilePhone.extend({ requiresOneOf: [self.homePhone, self.mobilePhone] });
 * self.homePhone.extend({ requiresOneOf: [self.homePhone, self.mobilePhone] }); 
 *
*/

ko.validation.rules['requiresOneOf'] = {
  getValue: function (o) {
    return (typeof o === 'function' ? o() : o);
  },
  validator: function (val, fields) {
    var self = this;

    var anyOne = ko.utils.arrayFirst(fields, function (field) {
      var stringTrimRegEx = /^\s+|\s+$/g,
                testVal;

      var val = self.getValue(field);

      if (val === undefined || val === null) 
        return !required;
      
      testVal = val;
      if (typeof (val) == "string") {
        testVal = val.replace(stringTrimRegEx, '');
      }

      return ((testVal + '').length > 0);

    });

    return (anyOne != null);
  },
  message: 'One of these fields is required'

};

####Change Limit Rule####

/**
 * Limits the maximum amount a numeric value can be changed.
 * Parameters: maxChange: <The max valid value change from base value>,
 *             baseValueAccessor: <A function to access the base value>
 * 
 * Example: 'Distance can change a maximum of 10'
 * var initDistance = 5;
 * this.distance.extend({
 *     changeLimit:{
 *         maxChange:10,
 *         baseValueAccessor:function () {
 *             return initDistance;
 *         }
 *     }
 * });
 * 
 */
ko.validation.rules['changeLimit'] = {
    validator: function(val, options) {
        return Math.abs(val - options.baseValueAccessor()) <= options.maxChange;
    },
    message: 'Change limit exeeded'
};

####Valid Object####

/*
 * Aggregate validation of all the validated properties within an object
 * Parameter: true|false
 * Example:
 *
 * viewModel = {
 *    person: ko.observable({
 *       name: ko.observable().extend({ required: true }),
 *       age: ko.observable().extend({ min: 0, max: 120 })
 *    }.extend({ validObject: true })
 * }   
*/
ko.validation.rules["validObject"] = {
    validator: function (obj, bool) {
        if (!obj || typeof obj !== "object") {
            throw "[validObject] Parameter must be an object";
        }
        return bool === (ko.validation.group(obj)().length === 0);
    },
    message: "Every property of the object must validate to '{0}'"
};

####Valid Array####

/*
 * Aggregate validation of all the validated elements within an array
 * Parameter: true|false
 * Example
 *
 * viewModel = {
 *    person: ko.observableArray([{
 *       name: ko.observable().extend({ required: true }),
 *       age: ko.observable().extend({ min: 0, max: 120 })
 *    }, {
 *       name: ko.observable().extend({ required: true }),
 *       age: ko.observable().extend({ min:0, max:120 })
 *    }].extend({ validArray: true })
 * }   
*/
ko.validation.rules["validArray"] = {
    validator: function (arr, bool) {
        if (!arr || typeof arr !== "object" || !(arr instanceof Array)) {
            throw "[validArray] Parameter must be an array";
        }
        return bool === (arr.filter(function (element) {
            return ko.validation.group(ko.utils.unwrapObservable(element))().length !== 0;
        }).length === 0);
    },
    message: "Every element in the array must validate to '{0}'"
};

####htmlNotEmpty####

ko.validation.rules['htmlNotEmpty'] = {
    validator: function (val, otherVal) {
    
        function isBlank(str) {
            return (!str || !str.match(/\S/));
        }

        function isEmpty(str) {
            return (!str || 0 === str.length);
        }
        
        function isHtmlEmpty(str) {
            if (!str.match(/^\s*?\\</)) return false;
            var s = $(str).text();
            return (isEmpty(s) || isBlank(s));
        }
    
        var invalid = isEmpty(val);
        if (!invalid) invalid = isHtmlEmpty(val);

        return !invalid;
    },
    message: 'Invalid.  Please enter a value'
};

####Nullable Integer####

ko.validation.rules['nullableInt'] = {
    validator: function (val, validate) {
        return val === null || val === "" || (validate && /^-?\d*$/.test(val.toString()));
    },
    message: 'Must be empty or an integer value'
};

####Nullable Decimal####

ko.validation.rules['nullableDecimal'] = {
    validator: function (val, validate) {
        return val === null || val === "" || (validate && /^-?\d*(?:\.\d*)?$/.test(val.toString()));
    },
    message: 'Must be empty or a decimal value'
};

####Conditional Required####

/*
 * Determines if a field is required or not based on a function or value
 * Parameter: boolean function, or boolean value
 * Example
 *
 * viewModel = {
 *   var vm = this;
 *   vm.isRequired = ko.observable(false);
 *   vm.requiredField = ko.observable().extend({ conditional_required: vm.isRequired});
 * }   
*/
ko.validation.rules['conditional_required'] = {
    validator: function (val, condition) {
        var required = false;
        if (typeof condition == 'function') {
            required = condition();
        }
        else {
            required = condition;
        }

        if (required) {
            return !(val == undefined || val == null || val.length == 0);
        }
        else {
            return true;
        }
    },
    message: "Field is required"
}

####Credit Card####

//This rules checks the credit card details 
//The card number (inferred) as well as the card type (via the card type field) are required 
//This checks the length and starting digits of the card per the type
//It also checks the checksum (see http://en.wikipedia.org/wiki/Luhn_algorithm)
//The card type field must return 'vc' for visa, 'mc' for mastercard, 'ae' for amex
//This is based on code from here: http://www.rahulsingla.com/blog/2011/08/javascript-implementing-mod-10-validation-(luhn-formula)-for-credit-card-numbers
//Example:
//
//self.cardNumber.extend({ creditCard: self.cardType });
ko.validation.rules['creditCard'] = {
	getValue: function (o) {
		return (typeof o === 'function' ? o() : o);
	},
	validator: function (val, cardTypeField) {
		var self = this;

		var cctype = self.getValue(cardTypeField);
		if (!cctype) return false;
		cctype = cctype.toLowerCase();

		if (val.length < 15) {
			return (false);
		}
		var match = cctype.match(/[a-zA-Z]{2}/);
		if (!match) {
			return (false);
		}

		var number = val;
		match = number.match(/[^0-9]/);
		if (match) {
			return (false);
		}

		var fnMod10 = function (number) {
			var doubled = [];
			for (var i = number.length - 2; i >= 0; i = i - 2) {
				doubled.push(2 * number[i]);
			}
			var total = 0;
			for (var i = ((number.length % 2) == 0 ? 1 : 0) ; i < number.length; i = i + 2) {
				total += parseInt(number[i]);
			}
			for (var i = 0; i < doubled.length; i++) {
				var num = doubled[i];
				var digit;
				while (num != 0) {
					digit = num % 10;
					num = parseInt(num / 10);
					total += digit;
				}
			}

			if (total % 10 == 0) {
				return (true);
			} else {
				return (false);
			}
		}

		switch (cctype) {
			case 'vc':
			case 'mc':
			case 'ae':
				//Mod 10 check
				if (!fnMod10(number)) {
					return false;
				}
				break;
		}
		switch (cctype) {
			case 'vc':
				if (number[0] != '4' || (number.length != 13 && number.length != 16)) {
					return false;
				}
				break;
			case 'mc':
				if (number[0] != '5' || (number.length != 16)) {
					return false;
				}
				break;

			case 'ae':
				if (number[0] != '3' || (number.length != 15)) {
					return false;
				}
				break;

			default:
				return false;
			}

		return (true);
	},
	message: 'Card number not valid.'
};

####isUnique####

/* Validates that all values in an array are unique. 
To initialize the simple validator provide an array to compare against. 
By default this will simply compare do an exactly equal (===) operation against each element in the supplied array.
For a little more control, initialize the validator with an object instead. The object should contain two properties: array and predicate. 
The predicate option enables you to provide a function to define equality. The array option can be observable. 

SIMPLE EXAMLE::
model.thisProp.extend({ isUnique: model.thoseProps });

COMPLEX EXAMLE::
model.selectedOption.extend({ isUnique: {
    array: model.options,
    predicate: function (opt, selectedVal) {
        return ko.utils.unwrapObservable(opt.id) === selectedVal;
    }
}});
*/

ko.validation.rules['isUnique'] = {
    validator: function (newVal, options) {
        if (options.predicate && typeof options.predicate !== "function")
            throw new Error("Invalid option for isUnique validator. The 'predicate' option must be a function.");

        var array = options.array || options;
        var count = 0;
        ko.utils.arrayMap(ko.utils.unwrapObservable(array), function(existingVal) {
            if (equalityDelegate()(existingVal, newVal)) count++;
        });
        return count < 2;
        
        function equalityDelegate() {
            return options.predicate ? options.predicate : function(v1, v2) { return v1 === v2; };
        }
    },
    message: 'This value is a duplicate',
};