Add Serialization to JSON String and Cocoa Touch Native Objects

[c0rrzin]

references #694

TODO:

• Change Cocoa-touch serializers' method signatures
• Add test cases for circular references
• Use RLMDynamicGet() instead of performing primitive selectors

[alazier]

Might be better to call this method JSONDictionary

[alazier]

Good start. We should definitely be using `RLMDyamicGet`` instead of calling primitive selectors.

[c0rrzin]

I updated the PR's description so that everyone can keep track of what's missing.

[c0rrzin]

@alazier I don't have access to the CI, but I think the build is not passing due to the unpredictability of [NSJSONSerialization dataWithJSONObject:options:error] parsing order. Do you have any idea how can this problem be solved? (I know that deep down we are testing the API, but I think it's nice to have the strings tested too)

Thanks.

[alazier]

The two failing test conditions are:

x testAllKindSerialization, ((objTestDictionary) equal to (objDictionary)) failed: ("{
x testAllKindSerialization, ((objTestString) equal to (objString)) failed: ("{

I'm not sure which objects don't align for the first case - my guess would be either the date or the binary data. For the second case, we could simply parse the strings using NSJSONSerialization and compare the dictionaries. I don't think there is a reliable way to compare the strings directly.

[tgoyne]

Both tests are in fact failing due to dictionary keys not being in a consistent order. I agree it'd be nice to test the exact string to verify that non-semantic things like formatting are correct, but I don't think that's possible for anything involving multiple items in a dictionary.

[c0rrzin]

@tgoyne I've been researching and did not found a simple way for doing that as well. Maybe I should test every valid property type and then maybe also test the count of properties after serializing. Will it be enough?

[bmunkholm]

Arrat -> Array

[bmunkholm]

indentation must be 4 spaces (allover)

[bmunkholm]

Need to update /CHANGELOG.md as well.

[bmunkholm]

We already got a version of similar serialization in core that we should consider using to centralize the functionality if possible.

[c0rrzin]

@bmunkholm how should we proceed then? Is the API accessible via tightdb headers?

[alazier]

@bmunkholm @c0rrzin the core apis are not suitable for everything we need to do in the objc api. For instance we need to support bi-directional keyPath mapping, custom date formatters, and perhaps at some point arbitrary transformations. As discussed previously it makes sense to get this working first in the objc api and then provide the needed functionality in core so this functionality can be shared across all apis.

[c0rrzin]

I'm thinking if this serializer isn't complex enough to be encapsulated. @alazier @bmunkholm ?

[alazier]

I'm not sure yet. I think what we want to do next is put together a full list of requirements, and come up with an api which best addresses those requirements. Will hopefully be able to get to this sometime this week.

As far as having multiple classes, at this point I'm envisioning we have at least on other class which allows users to specify JSON mappings, formatters, and other transformation. This could potentially be passed into the method used to generate JSON, or perhaps you could have a mapper that is used by default. It won't be possible to do this well though until we have the full list of features/requirements we hope to support so defining those should definitely be the next step.

[c0rrzin]

@alazier agreed. If you need any help while writing this list, I can provide an initial template or something else. I think it's valid taking a look at this framework to see how they did it.

[icanzilb]

"they" is basically me. ping me if you need some help I've been developing actively JSONModel for about 2 years

[jpsim]

retest this please (please ignore, this is just for CI)

[segiddins]

@c0rrzin we're unfortunately unable to merge this pull request.
For a feature as key as JSON/object mapping, we need to first map out the desired API specification before implementation, from the top down. We'll let you know when we have a pull request with our designs, and we welcome your feedback on it.
Thanks so much for your contribution to Realm, we really appreciate it when people take the time to contribute.

[c0rrzin]

@segiddins I really enjoyed spending some time with the project and sure would like to effectively contribute and provide feedback on the design that Realm's team will come up with so it suits its needs.