On 01.02.2017 14:21,Anastasia Lubennikova wrote:
Now the simplest way to extract booleans and numbers from json/jsonb is
to cast it to text and then cast to the appropriate type: ...
This patch implements direct casts from jsonb numeric (jbvNumeric) to
numeric, int4 and float8, and from jsonb bool (jbvBool) to bool.
Thank you for this patch. I always wanted to add such casts by myself.
If you find it useful, I can also add support of json and other types,
such as smallint and bigint.
Yes, I'd like to have support for other types and maybe for json.
Some comments about the code: I think it would be better to
* add function for extraction of scalars from pseudo-arrays
* iterate until WJB_DONE to pfree iterator
Example:
static bool
JsonbGetScalar(Jsonb *jb, JsonbValue *v)
{
JsonbIterator *it;
JsonbIteratorToken tok;
JsonbValue jbv;
if (!JB_ROOT_IS_SCALAR(jb))
return false;
/*
* A root scalar is stored as an array of one element, so we get the
* array and then its first (and only) member.
*/
it = JsonbIteratorInit(&jb->root);
tok = JsonbIteratorNext(&it, &jbv, true);
Assert(tok == WJB_BEGIN_ARRAY);
tok = JsonbIteratorNext(&it, v, true);
Assert(tok == WJB_ELEM);
tok = JsonbIteratorNext(&it, &jbv, true);
Assert(tok == WJB_END_ARRAY);
tok = JsonbIteratorNext(&it, &jbv, true);
Assert(tok == WJB_DONE);
return true;
}
Datum
jsonb_int4(PG_FUNCTION_ARGS)
{
Jsonb *in = PG_GETARG_JSONB(0);
JsonbValue v;
if (!JsonbGetScalar(in, &v) || v.type != jbvNumeric)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("key value must be json numeric")));
PG_RETURN_INT32(DatumGetInt32(DirectFunctionCall1(numeric_int4,
NumericGetDatum(v.val.numeric))));
}
--
Nikita Glukhov
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
