Adding requiresFieldIfEmpty validator.

README.md

@@ -167,6 +167,7 @@ components following the same API.
 ### Validators
 
 * matchField
+* requiresFieldIfEmpty
 * min
 * max
 * range

example/complex.js

@@ -31,6 +31,12 @@ var form = forms.create({
         required: true,
         validators: [validators.matchField('password')]
     }),
+    phone_1: fields.string({
+        validators: [validators.requiresFieldIfEmpty('phone_2')]
+    }),
+    phone_2: fields.string({
+        validators: [validators.requiresFieldIfEmpty('phone_1')]
+    }),
     options: fields.string({
         choices: {
             one: 'option one',

lib/validators.js

@@ -30,6 +30,21 @@ exports.matchField = function (match_field, message) {
     };
 };
 
+exports.requiresFieldIfEmpty = function (alternate_field, message) {
+    if (!message) { message = 'One of %s or %s is required.'; }
+    var validator = function (form, field, callback) {
+        var alternateBlank = trim(form.fields[alternate_field].data).length === 0,
+            fieldBlank = trim(field.data).length === 0;
+        if (alternateBlank && fieldBlank) {
+            callback(util.format(message, field.name, alternate_field));
+        } else {
+            callback();
+        }
+    };
+    validator.forceValidation = true;
+    return validator;
+};
+
 exports.min = function (val, message) {
     if (!message) { message = 'Please enter a value greater than or equal to %s.'; }
     return function (form, field, callback) {

test/test-validators.js

@@ -21,6 +21,39 @@ exports.matchField = function (test) {
     });
 };
 
+exports.requiresFieldIfEmpty = function (test) {
+    var v = validators.requiresFieldIfEmpty('alternate_field', 'field 1: %s field2: %s'),
+        empty_fields = {
+            field: {name: 'field', data: ' '},
+            alternate_field: {name: 'alternate_field', data: ''}
+        },
+        filled_fields = {
+            field: {name: 'field', data: 'filled'},
+            alternate_field: {name: 'alternate_field', data: 'also filled'}
+        },
+        first_filled = {
+            field: {name: 'field', data: 'filled'},
+            alternate_field: {name: 'alternate_field', data: ''}
+        },
+        second_filled = {
+            field: {name: 'field', data: ''},
+            alternate_field: {name: 'alternate_field', data: 'filled'}
+        };
+    v({ fields: empty_fields }, empty_fields.field, function (err) {
+        test.equals(err, 'field 1: field field2: alternate_field');
+        v({ fields: filled_fields }, filled_fields.field, function (err) {
+            test.equals(err, undefined);
+            v({ fields: first_filled }, first_filled.field, function (err) {
+                test.equals(err, undefined);
+                v({ fields: second_filled }, second_filled.field, function (err) {
+                    test.equals(err, undefined);
+                    test.done();
+                });
+            });
+        });
+    });
+};
+
 exports.min = function (test) {
     validators.min(100, 'Value must be greater than or equal to %s.')('form', {data: 50}, function (err) {
         test.equals(err, 'Value must be greater than or equal to 100.');