[OASIS Issue Tracker] (ODATA-1336) Querying "JSON properties"

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

Ralf Handl created ODATA-1336:
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             Summary: Querying "JSON properties"
                 Key: ODATA-1336
                 URL: https://issues.oasis-open.org/browse/ODATA-1336
             Project: OASIS Open Data Protocol (OData) TC
          Issue Type: New Feature
          Components: Vocabularies
    Affects Versions: V4.01_CS01
         Environment: Proposed
            Reporter: Ralf Handl


"JSON properties" are stream properties whose value is of media type {{application/json}} or one of its subtypes. They were introduced with ODATA-1177.

As outlined inÂ[OData Extension for JSON Data|https://www.oasis-open.org/committees/download.php/46559/OData%20Extension%20for%20JSON%20Data%20v1.0.doc] we need query capabilities on these properties.

Requirements:
 # Address parts of the JSON stream values in common expressions, e.g. in {{$filter}}, {{$compute}}, {{$orderby}}
 # Specify a JSON Schema that describes/restricts the JSON stream values

The first requirement can e.g. be solved via bound functions on JSON stream properties, e.g.
 * extract/compute an OData value (primitive, complex, collection) from a JSON stream
 * special case:Âextract/compute a JSON stream from a JSON stream
 * special case:Âextract/compute a Boolean value from a JSON stream

These functions can be inspired by (or be direct wrappers for) the SQL/JSON functions
 * JSON_QUERY, see [Microsoft SQL Server|https://docs.microsoft.com/en-us/sql/t-sql/functions/json-query-transact-sql?view=sql-server-2017] or [SAP HANA|https://help.sap.com/viewer/4fe29514fd584807ac9f2a04f6754767/2.0.03/en-US/3126ea33d50d42d19517a08fe22ec5a1.html]
 * JSON_VALUE, seeÂ[Microsoft SQL Server|https://docs.microsoft.com/en-us/sql/t-sql/functions/json-value-transact-sql?view=sql-server-2017] or [SAP HANA|https://help.sap.com/viewer/4fe29514fd584807ac9f2a04f6754767/2.0.02/en-US/9355cb9e45a149c1a6ddb2bd2392d864.html]

Google BigQuery Standard SQL has similar JSON functions [JSON_EXTRACT and JSON_EXTRACT_SCALAR|https://cloud.google.com/bigquery/docs/reference/standard-sql/json_functions] that use the same path syntax to address parts of the JSON value.

PostgreSQL has its own set of [JSON Functions and Operators|https://www.postgresql.org/docs/9.4/functions-json.html].



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