Change in syntax for URI param 'q'

[kzangeli]

Attribute Exists & Not Exists, right now use '+' and '-' in the URI param 'q':

GET /v2/entities?q=+attr1;-attr2

However, the '+' is decoded to a SPACE by MHD and a decision has been made to change the syntaxis, using 'no prefix' for EXISTS and '!' for NOT EXISTS:

GET /v2/entities?q=attr1;!attr2

We also use '+/-' for TYPE EXISTS:

GET /v2/entities?q=+type

That syntaxis must be changed the same way, to:

GET /v2/entities?q=type       # Get entities that have a type
GET /v2/entities?q=!type      # Get entities that DO NOT have a type

Actions to be taken:

1. Change the source code (qStringFilters in MongoGlobal.cpp)
2. Modify existing functests that use the old syntaxis
3. (if not fully covered), new functests
4. Modify documentation (.apib ngsiv2), including changing examples in the doc using the old syntax

Related issues:
#1589
#1587

[fgalan]

Maybe #1587 is also related (at least partially)

[fgalan]

In addition, after completing this issue the following .test need to be enabled (after modifications):

• 1587_q_query_has_type/q_query_has_type.test
• 1589_query_entities_with_specific_attributes/query_entities_with_specific_attributes.test.pending1675.DISABLED

[fgalan]

Fixed by PR #1756 (mainly) and #1760 (two disabled .test).

[iariasleon]

Reopen because is pending to test by QA

[iariasleon]

LGTM

[fgalan]

Changed milestone to 0.28.0, the one in which this will really fixed (see https://github.com/telefonicaid/fiware-orion/releases/tag/0.28.0 and look for "1751").