fullGeoJson flag for Feature and FeatureCollection attributes

[fgalan]

After some internal discussion, we have decided that the processing of Feature and FeatureCollection geo:json attributes (issue #4114) will involve a normalization in GET/notification stage. That is, CB will accept the Feature and FeatureCollection format in attribute creating/update but in attribute GET/notification only the geometry will be returned.

This involves a lost of information in the attribute being created/update (in particular, the properties field associate to the Feature). For current use case, that information is not needed, but maybe it is needed in the future. Thus:

1. At the present moment, CB stores in DB the attribute Feature/FeatureCollection value as it was created/updated
2. A new option flag will be developed to specify that the user want the full Feature or FeatureCollection representation. In particular:
   • A new option for GET, eg. ?options=fullGeoJson
   • A new boolean field for subscriptions, e.g. "fullGeoJson": true|false
3. The default mode will be as we have now (version 3.7.0), to ensure backward compatibility. That is, not returning full Geo JSON

[fgalan]

A new option for GET, eg. ?options=fullGeoJson

The following .test files (pay attention at commit hash) can be useful when implementing that:

https://github.com/telefonicaid/fiware-orion/tree/3cc7ff753c0b24a953e79b22ff57032b960f579e/test/functionalTest/cases/4114_geojson_feature_support

(The correspond to a version of the code when we think that the "full GeoJSON mode" were what we need)

[fgalan]

Documentation doc/manuals/user/ngsiv2_implementation_notes.md has a paragrah:

Note that actually Orion stores the full value used at Feature or FeatureCollection
creation/updating time. However, from the point of view of normalization with other geo:json types,
it has been decided to return only the geometry part. In the future, maybe a flag to return
the full content would be implemented (more detail in this issue).

That would need to be adapted upon fixing of this issue.

[fgalan]

Implementation notes:

In ContextAttribute::toJson() this is the key part:

  if (compoundValueP != NULL)
  {
    orion::CompoundValueNode* childToRenderP = compoundValueP;
    if (type == GEO_JSON)
    {
      childToRenderP = getGeometry(compoundValueP);
    }

    // Some internal error conditions in getGeometryToRender() (e.g. out of band manipulation
    // of DB entities) may lead to NULL, so the check is needed
    if (childToRenderP != NULL)
    {
      jh.addRaw("value", childToRenderP->toJson());
    }
  }

The new flag has to be taken into account in if (type == GEO_JSON) so getGeometry() doesn't get invoked if full GeoJSON is requested.