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JSONB
Clear offers JSONB functions through
Clear::SQL::JSONB helper and the Expression Engine.JSONB is a great No-SQL mapping under PostgreSQL. It helps you to store value and documents which otherwise would be difficult
Let's imaging a table
events where you store the events of differents suppliers:The main limitation of JSONB is the "simple" syntax is not indexable. For example:
SELECT * FROM events WHERE payload->'source'->>'name' = 'Asana'
The code above will not use any indexes and will do a sequencial scan over your table.
However, using the
@> operator and a gin index on your column will improve drastically the performances: SELECT * FROM events WHERE payload @> '{"source": {"name": "Asana"}}'
Obviously, the second syntax is more complex and error prone. Clear offers leverage and simplicity:
Event.query.where{ payload.jsonb("source.name") == "asana" }
# SELECT * FROM events WHERE payload @> '{"source": {"name": "Asana"}}'
calling
node.jsonb(key) on expression node will resolve to:- node->'key_elm1'->'key_elm...n'
Using equality testing between a jsonb path and a literal will use the indexable notation
@> :where{ data.jsonb('a.b.c') == 1 }
#output:
# data @> '{"a":{"b":{"c":1}}}'
In the case the operation is not indexable (e.g. the value is variable, operator is not equality...), Clear will automatically switch back to the arrow
-> notation:where{ data.jsonb('a.b.c') == raw("NOW()") }
# output:
# data->'a'->'b'->'c' = NOW()
Casting
You can cast the element using
cast after your expression:where{ data.jsonb("a.b").cast("text") == "o" }
# output:
# data->'a'->'b'::text == 'o'
Note: If you cast the
jsonb, clear will never use @> operatorClear::SQL::JSONB.jsonb_resolve("data", "a.b.c", "text")
# output:
# data->'a'->'b'->'c'::text
Clear::SQL::JSONB.jsonb_eq(data, "a.b.c", "value")
#output:
# data @> {"a":{"b":{"c":"value"}}}