fix(input): format as string before running minlength/maxlength formatters

Previously, minlength/maxlength would not work correctly when dealing with non-string model values.

A better fix for this has already been implemented in 1.3, but unfortunately implementing that fix
in 1.2 is a bit harder as it requires a number of commits to be backported in order to solve the
problem correctly.

Closes angular#5936

Author: caitp

src/ng/directive/input.js

@@ -608,6 +608,7 @@ function textInputType(scope, element, attr, ctrl, $sniffer, $browser) {
   if (attr.ngMinlength) {
     var minlength = int(attr.ngMinlength);
     var minLengthValidator = function(value) {
+      if (typeof value !== 'string' && !ctrl.$isEmpty(value)) value = value.toString();
       return validate(ctrl, 'minlength', ctrl.$isEmpty(value) || value.length >= minlength, value);
     };
 
@@ -619,6 +620,7 @@ function textInputType(scope, element, attr, ctrl, $sniffer, $browser) {
   if (attr.ngMaxlength) {
     var maxlength = int(attr.ngMaxlength);
     var maxLengthValidator = function(value) {
+      if (typeof value !== 'string' && !ctrl.$isEmpty(value)) value = value.toString();
       return validate(ctrl, 'maxlength', ctrl.$isEmpty(value) || value.length <= maxlength, value);
     };
 

test/ng/directive/inputSpec.js

@@ -789,6 +789,20 @@ describe('input', function() {
       changeInputValueTo('aaa');
       expect(scope.value).toBe('aaa');
     });
+
+
+    it('should convert non-empty non-strings to string before formatting', function() {
+      compileInput('<input type="text" ng-model="value" name="alias" ng-minlength="3">');
+      scope.value = 10;
+      scope.$digest();
+
+      expect(scope.form.alias.$error.minlength).toBe(true);
+
+      scope.value = 100;
+      scope.$digest();
+
+      expect(scope.form.alias.$error.minlength).not.toBe(true);
+    });
   });
 
 
@@ -803,6 +817,20 @@ describe('input', function() {
       changeInputValueTo('aaa');
       expect(scope.value).toBe('aaa');
     });
+
+
+    it('should convert non-empty non-strings to string before formatting', function() {
+      compileInput('<input type="text" ng-model="value" name="alias" ng-maxlength="3">');
+      scope.value = 1000;
+      scope.$digest();
+
+      expect(scope.form.alias.$error.maxlength).toBe(true);
+
+      scope.value = 100;
+      scope.$digest();
+
+      expect(scope.form.alias.$error.maxlength).not.toBe(true);
+    });
   });