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Fix crash on invalid key path #230

merged 5 commits into from

2 participants


Fixed a crash when an invalid key path is indicated for a key in the JSONKeyPathsByPropertyKey method

David Cordero added some commits
David Cordero Add podspec file 22712f9
David Cordero Merge remote-tracking branch 'upstream/master' 1a6be4e
David Cordero Fix a crash when an invalid keypath is used 2807e4e
David Cordero Revert "Add podspec file"
This reverts commit 22712f9863a01091ad9f6b0bb186382204f8583e.

It's a little hard to tell what this is fixing. From the test, am I correct in understanding that it fixes a crash when a nested key path is specified in +JSONKeyPathsByPropertyKey, but the JSON contains a primitive instead of an object at some part of that path?

If so, we should fix this by stepping through the JSON dictionary manually, not catching exceptions. Exceptions in Objective-C are generally used to indicate unrecoverable errors, so catching them is rarely safe. (Mantle does so as a convenience for release code, and the value of even that has been debated.)


Yep it fix exactly that case. What exactly you mean with "stepping through the JSON dictionary manually" ? I mean, given the test case:

NSDictionary *values = @{
    @"username": @"foo",
    @"nested": @"bar",
    @"count": @"0"

with a + JSONKeyPathsByPropertyKey like this:

+ (NSDictionary *)JSONKeyPathsByPropertyKey {
    return @{
        @"name": @"username",
        @"nestedName": @"",
        @"weakModel": NSNull.null,

should we fill *error with a new error type an return nil from -(id)initWithJSONDictionary better than an Exception? or step over that key and continue with no error?


I mean that we shouldn't be executing code which will cause NSDictionary to throw an exception.

Instead, we should follow a generalized version of these steps:

  1. Break apart into two components: nested and name
  2. Retrieve nested from the dictionary. If it's not a dictionary itself, error out.
  3. Retrieve name from the nested dictionary.

Modified fix to avoid sending an exception an returning an error instead

@jspahrsummers jspahrsummers self-assigned this
@jspahrsummers jspahrsummers merged commit cf3bb6e into from

Thank you! I made some minor formatting changes in df03aa9, but otherwise this looks great! :star2:

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Commits on Dec 17, 2013
  1. Add podspec file

    David Cordero authored
Commits on Feb 4, 2014
  1. Merge remote-tracking branch 'upstream/master'

    David Cordero authored
  2. Fix a crash when an invalid keypath is used

    David Cordero authored
  3. Revert "Add podspec file"

    David Cordero authored
    This reverts commit 22712f9863a01091ad9f6b0bb186382204f8583e.
Commits on Feb 6, 2014
  1. @dcordero
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Showing with 34 additions and 1 deletion.
  1. +18 −1 Mantle/MTLJSONAdapter.m
  2. +16 −0 MantleTests/MTLJSONAdapterSpec.m
19 Mantle/MTLJSONAdapter.m
@@ -106,7 +106,24 @@ - (id)initWithJSONDictionary:(NSDictionary *)JSONDictionary modelClass:(Class)mo
NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
if (JSONKeyPath == nil) continue;
- id value = [JSONDictionary valueForKeyPath:JSONKeyPath];
+ id value = JSONDictionary;
+ NSArray *JSONKeyPathComponents = [JSONKeyPath componentsSeparatedByString:@"."];
+ for (NSString *itemJSONKeyPathComponent in JSONKeyPathComponents) {
+ if (![value isKindOfClass:NSDictionary.class]) {
+ if (error != NULL) {
+ NSDictionary *userInfo = @{
+ NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON dictionary", @""),
+ NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%@ could not be created because an invalid JSON dictionary was provided for keypath: %@", @""), NSStringFromClass(modelClass), JSONKeyPath],
+ };
+ *error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
+ }
+ return nil;
+ }
+ value = [value valueForKey:itemJSONKeyPathComponent];
+ if (value == nil) break;
+ }
if (value == nil) continue;
@try {
16 MantleTests/MTLJSONAdapterSpec.m
@@ -73,6 +73,22 @@
expect([MTLJSONAdapter JSONDictionaryFromModel:model]).to.equal(values);
+it(@"should return nil and error with an invalid key path from JSON",^{
+ NSDictionary *values = @{
+ @"username": @"foo",
+ @"nested": @"bar",
+ @"count": @"0"
+ };
+ NSError *error = nil;
+ MTLTestModel *model = [MTLJSONAdapter modelOfClass:MTLTestModel.class fromJSONDictionary:values error:&error];
+ expect(model).beNil();
+ expect(error).notTo.beNil();
+ expect(error.domain).to.equal(MTLJSONAdapterErrorDomain);
+ expect(error.code).to.equal(MTLJSONAdapterErrorInvalidJSONDictionary);
it(@"should return nil and an error with a nil JSON dictionary", ^{
NSError *error = nil;
MTLJSONAdapter *adapter = [[MTLJSONAdapter alloc] initWithJSONDictionary:nil modelClass:MTLTestModel.class error:&error];
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