feat!: JSON and YAML migration (Mapping -> Serializable)

[caspiano]

Fast-forward #28 to align with master.

Resolves #19
Resolves #14
Resolves #25

[kimburgess]

Suggested change

	def {{name}}_change : Tuple({{opts[:klass]}}?, {{opts[:klass]}}?)?
	def {{name}}_change : Tuple({{opts[:klass]}}?, {{opts[:klass]}})?

If there's a change, that should be to the type of the field (I think?)

[dukenguyenxyz]

Cannot type this, currently raise the following

error in line 2
Error: while requiring "./spec/model_spec.cr"


In spec/model_spec.cr:410:13

 410 | klass.string_change.should eq ({nil, "hello"})
             ^------------
Error: instantiating 'Inheritance#string_change()'


There was a problem expanding macro 'finished'

Called macro defined in macro 'inherited'

 20 | macro finished

Which expanded to:

 >  1 |       __process_attributes__
 >  2 |       __customize_orm__
 >  3 |       __track_local_fields__
 >  4 |       
 >  5 |       __track_changes__
 >  6 |       __map_json__
 >  7 |       __create_initializer__
 >  8 |       __getters__
 >  9 |       __nilability_validation__
 > 10 |       
 > 11 |     
Error: expanding macro


There was a problem expanding macro '__track_local_fields__'

Called macro defined in src/active-model/model.cr:274:3

 274 | macro __track_local_fields__

Which expanded to:

 >  1 |     
 >  2 |       @[JSON::Field(ignore: true)]
 >  3 |       @[YAML::Field(ignore: true)]
 >  4 |       getter? string_changed  = false
 >  5 | 
 >  6 |       # Include `string` in the set of changed attributes, whether it has changed or not.
 >  7 |       def string_will_change! : Nil
 >  8 |         @string_changed = true
 >  9 |         @string_was = @string.dup
 > 10 |       end
 > 11 | 
 > 12 |       @[JSON::Field(ignore: true)]
 > 13 |       @[YAML::Field(ignore: true)]
 > 14 |       getter string_was : String | Nil = nil
 > 15 | 
 > 16 |       # Returns a Tuple of the previous and the current
 > 17 |       # value of an instance variable if it has changed
 > 18 |       def string_change : Tuple(String?, String)?
 > 19 |         {@string_was, @string} if string_changed?
 > 20 |       end
 > 21 |     
 > 22 |       @[JSON::Field(ignore: true)]
 > 23 |       @[YAML::Field(ignore: true)]
 > 24 |       getter? integer_changed  = false
 > 25 | 
 > 26 |       # Include `integer` in the set of changed attributes, whether it has changed or not.
 > 27 |       def integer_will_change! : Nil
 > 28 |         @integer_changed = true
 > 29 |         @integer_was = @integer.dup
 > 30 |       end
 > 31 | 
 > 32 |       @[JSON::Field(ignore: true)]
 > 33 |       @[YAML::Field(ignore: true)]
 > 34 |       getter integer_was : Int32 | Nil = nil
 > 35 | 
 > 36 |       # Returns a Tuple of the previous and the current
 > 37 |       # value of an instance variable if it has changed
 > 38 |       def integer_change : Tuple(Int32?, Int32)?
 > 39 |         {@integer_was, @integer} if integer_changed?
 > 40 |       end
 > 41 |     
 > 42 |       @[JSON::Field(ignore: true)]
 > 43 |       @[YAML::Field(ignore: true)]
 > 44 |       getter? no_default_changed  = false
 > 45 | 
 > 46 |       # Include `no_default` in the set of changed attributes, whether it has changed or not.
 > 47 |       def no_default_will_change! : Nil
 > 48 |         @no_default_changed = true
 > 49 |         @no_default_was = @no_default.dup
 > 50 |       end
 > 51 | 
 > 52 |       @[JSON::Field(ignore: true)]
 > 53 |       @[YAML::Field(ignore: true)]
 > 54 |       getter no_default_was : String | Nil = nil
 > 55 | 
 > 56 |       # Returns a Tuple of the previous and the current
 > 57 |       # value of an instance variable if it has changed
 > 58 |       def no_default_change : Tuple(String?, String)?
 > 59 |         {@no_default_was, @no_default} if no_default_changed?
 > 60 |       end
 > 61 |     
 > 62 |   
Error: method Inheritance#string_change must return (Tuple(String | Nil, String) | Nil) but it is returning (Tuple(String | Nil, String | Nil) | Nil)

[kimburgess]

Can these #responds_to? calls be replaced with a proper type check instead (possibly as a restriction on the method argument)?

[dukenguyenxyz]

cannot type the method argument here, possible types include JSON::PullParser (or YAML::PullParser in the case of YAML), String, IO, however we have to do a runtime check since only IO::Sized < IO responds to read_remaining, which we cannot detect from arg_type and can only do so once json.read_string (i.e. record the string then read_next

[kimburgess]

As converter applies to both JSON and YAML serialisation, it would be good to either:

1. provide the ability to specify seperate JSON / YAML converters, or
2. provide the ability to specify key, emit_null and root that's used in both JSON and YAML (unless otherwise specified).

[caspiano]

I would prefer these options to default to the unprefixed argument, with the option to override via a prefixed argument

[dukenguyenxyz]

sorry I'm not exactly sure what this means, could you please clarify?

[caspiano]

Kim: json_converter and yaml_converter
Me: Support unprefixed arguments, like root, that is passed to both the json and yaml prefixed arguments. If, in my example, json_root is defined, use that instead of root