Incorrect edge schema generation in 0.7.0

[volodymyrko]

Hi there seems be an issue with generating schema (CollectionBase.schema) for Edges/Relations with custom attributes (like SpecializesIn ) in specific case. Here are few examples:

1. when schema method is run for SpecializesIn first (before any other relations) everything is fine

   
   (Pdb) self._graph.edges['specializes_in'].schema().fields.keys()
   <class 'tests.data.SpecializesIn'>
   dict_keys(['expertise_level', '_key'])   # 'expertise_level' is present

(Pdb) self._graph.edges['studies'].schema().fields.keys() <class 'arango_orm.collections.Relation'> dict_keys([])

2. if `schema` method is run for Relation first it  does not generate correct schema

(Pdb) self._graph.edges['studies'].schema().fields.keys() <class 'arango_orm.collections.Relation'> dict_keys([])

(Pdb) self._graph.edges['specializes_in'].schema().fields.keys() <class 'tests.data.SpecializesIn'> dict_keys([]) # IS EMPTY

is happens because `Relation._cls_schema` is already generated/cached at the first step (`self._graph.edges['studies'].schema()`) and it is used when `self._graph.edges['specializes_in'].schema()` is run. `SpecializesIn` is inherited from `Relation` so it uses  `Relation._cls_schema` data

[SoundsSerious]

Hi @volodymyrko

I agree there are some issues with the schema caching. This was something I implemented as I found repeated calls to the schema generated actually created a pretty significant memory leak.

I dont know what the right answer is, a couple ideas have been floated:

1. get rid of marshmallow which has been causing some problems like the memory leak
2. provide an explicit method to cache schema #119
3. improve the caching #115

[overbost]

@volodymyrko can you check the last commit #122 (it's merged into master now). This should fix your issue.

[volodymyrko]

@overbost , my tests passed successfully. thanks

[PTank]

Hi, can you update the pypi package to the last version to fix this issue ? Thanks

[kashifpk]

@PTank Done. @PTank @volodymyrko @overbost @SoundsSerious Please use https://github.com/kashifpk/arango-orm for the future as I no longer have push access to this repo. I'll be pushing updates to this new repo in the future.