option to ignore initial values?

[larshp]

I have the following code,

DATA intf TYPE zif_aff_intf_v1=>ty_main.
DATA li_ajson TYPE REF TO zif_abapgit_ajson.
intf-header-description = 'hello world'.
li_ajson = zcl_abapgit_ajson=>create_empty( ).
li_ajson->keep_item_order( ).
li_ajson->set(
  iv_path = '/'
  iv_val  = intf ).
DATA(json) = li_ajson->stringify( 2 ).
BREAK-POINT.

it creates the following json,

{
  "schema": "",
  "header": {
    "description": "hello world",
    "original_language": "",
    "abap_language_version": ""
  },
  "category": "00",
  "proxy": false,
  "descriptions": {
    "types": [],
    "attributes": [],
    "events": [],
    "methods": []
  }
}

I'd like to ignore initial fields, ie. expected outcome is

{
  "header": {
    "description": "hello world"
  }
}

any suggestions/thoughts on implementing this?

[sbcgua]

Should not be difficult to implement.
There is ignore_empty flag in set. However it works for the whole value. I'm wondering if it is semantically correct to extend the same flag to components of a structure ... or it should be a separate flag ? Currently gravitating towards the former.

[larshp]

also, I'm considering extending the custom mapping class/interface to also be able to handle values, as I'd like to keep some initial values

[larshp]

perhaps something like adding this method to the custom mapping interface

methods to_json_skip_value
  importing 
    io_type type ref to cl_abap_typedescr
    is_node type ty_node,
  returning 
    value(rv_skip) type abap_bool.

if it returns rv_skip = abap_true, then skip the value, else as normal

[sbcgua]

Separated the last comment into an issue #72 (good idea by the way !)

Looking into ignore_empty ... there is a stupid issue on the way ... ignore_empty = true by default :) So current semantics can be used somewhere already. Does it make sense that it is true by default? and thus:

• ajson skips direct empty values
• and also skips all deep empty attrs of structures? And structures in structures ? And structures in tables ? (but not empty table items, unless the whole table is empty) ... hmmm

UPD: Otherwise we need a separate flag for deep skipping .. or just implement #72 as the only way to do it

[larshp]

having ignore_empty on by default, might be a breaking change, not for ABAP, but if there are consumers of the json in languages that respect undefined

but anyhow, I'm all for breaking stuff #keepTheCoreMoving

[sbcgua]

In the meantime I think it is "just implement #72 as the only way to do it"... (in progress)

[larshp]

yea, so close this issue?

[sbcgua]

Not yet, let's keep it for clarity, the task is a bit more difficult than I thought

[sbcgua]

@larshp reimagining the feature ... what is the final purpose of the feature?
Is it a json tree that skips certain values on set ?

json state: { a: 1, b: 2 }
li_json-set( iv_path = '/filtered/node' iv_value = xxx )
json state: { a: 1, b: 2 }

Or is it a serialized json without certain nodes ?

json state: { a: 1, b: 2 }
li_json-set( iv_path = '/filtered/node' iv_value = xxx )
json state: { a: 1, b: 2, filtered: { node: xxx } }
li_json->serialize( ) => "{ a: 1, b: 2 }"

I believe it is the 2nd

The first feature is adding a lot of complexity when setting values. While the 2nd is separatable in an independent logic

...
json state: { a: 1, b: 2, filtered: { node: xxx } }
li_json2 = li_json->filter( li_filter_instance )
json2 state: { a: 1, b: 2 }
li_json2->serialize( ) => "{ a: 1, b: 2 }"

Does it make sense ?

Why complexity - because of deep nature of json. E.g. the above example adds '/filtered/node' where filtered does not exit yet. So ! Both '/filtered/node' and '/filtered' must be skipped. Or if '/filtered' already exist then it should stay. Not only will it make set mote complex but also slower.

[sbcgua]

The filter was implemented, can this be closed ?