<para>

<xref linkend="functions-json-creation-table"> shows the functions that are

available for creating <type>json</type> values.

(Currently, there are no equivalent functions for <type>jsonb</>, but you

can cast the result of one of these functions to <type>jsonb</>.)

available for creating <type>json</type> and <type>jsonb</type> values.

(There are no equivalent functions for <type>jsonb</>, of the <literal>row_to_json</>

and <literal>array_to_json</> functions. However, the <literal>to_jsonb</>

function supplies much the same functionality as these functions would.)

</para>

<indexterm>

<indexterm>

<primary>json_object</primary>

</indexterm>

<indexterm>

<primary>to_jsonb</primary>

</indexterm>

<indexterm>

<primary>jsonb_build_array</primary>

</indexterm>

<indexterm>

<primary>jsonb_build_object</primary>

</indexterm>

<indexterm>

<primary>jsonb_object</primary>

</indexterm>

<table id="functions-json-creation-table">

<title>JSON Creation Functions</title>

</thead>

<tbody>

<row>

<entry><para><literal>to_json(anyelement)</literal>

</para><para><literal>to_jsonb(anyelement)</literal>

</para></entry>

<entry>

<literal>to_json(anyelement)</literal>

</entry>

<entry>

Returns the value as JSON. Arrays and composites are converted

Returns the value as <type>json</> or <type>jsonb</>.

Arrays and composites are converted

(recursively) to arrays and objects; otherwise, if there is a cast

from the type to <type>json</type>, the cast function will be used to

perform the conversion; otherwise, aJSONscalar value is produced.

perform the conversion; otherwise, a scalar value is produced.

For any scalar type other than a number, a Boolean, or a null value,

the text representation will be used,properly quoted and escaped

so that it is a valid JSON string.

the text representation will be used,in such a fashion that it is a

valid <type>json</> or <type>jsonb</> value.

</entry>

<entry><literal>to_json('Fred said "Hi."'::text)</literal></entry>

<entry><literal>"Fred said \"Hi.\""</literal></entry>

<entry><literal>{"f1":1,"f2":"foo"}</literal></entry>

</row>

<row>

<entry>

<literal>json_build_array(VARIADIC "any")</literal>

</entry>

<entry><para><literal>json_build_array(VARIADIC "any")</literal>

</para><para><literal>jsonb_build_array(VARIADIC "any")</literal>

</para></entry>

<entry>

Builds a possibly-heterogeneously-typed JSON array out of a variadic

argument list.

<entry><literal>[1, 2, "3", 4, 5]</literal></entry>

</row>

<row>

<entry>

<literal>json_build_object(VARIADIC "any")</literal>

</entry>

<entry><para><literal>json_build_object(VARIADIC "any")</literal>

</para><para><literal>jsonb_build_object(VARIADIC "any")</literal>

</para></entry>

<entry>

Builds a JSON object out of a variadic argument list. By

convention, the argument list consists of alternating

<entry><literal>{"foo": 1, "bar": 2}</literal></entry>

</row>

<row>

<entry>

<literal>json_object(text[])</literal>

</entry>

<entry><para><literal>json_object(text[])</literal>

</para><para><literal>jsonb_object(text[])</literal>

</para></entry>

<entry>

Builds a JSON object out of a text array. The array must have either

exactly one dimension with an even number of members, in which case

<entry><literal>{"a": "1", "b": "def", "c": "3.5"}</literal></entry>

</row>

<row>

<entry>

<literal>json_object(keys text[], values text[])</literal>

</entry>

<entry><para><literal>json_object(keys text[], values text[])</literal>

</para><para><literal>json_object(keys text[], values text[])</literal>

</para></entry>

<entry>

This form of <function>json_object</> takes keys and values pairwise from two separate

arrays. In all other respects it is identical to the one-argument form.

function <function>json_agg</function> which aggregates record

values as JSON, and the aggregate function

<function>json_object_agg</function> which aggregates pairs of values

into a JSON object.

into a JSON object, and their <type>jsonb</type> equivalents,

<function>jsonb_agg</> and <function>jsonb_object_agg</>.

</para>

</sect1>

<entry>aggregates records as a JSON array of objects</entry>

</row>

<row>

<entry>

<indexterm>

<primary>jsonb_agg</primary>

</indexterm>

<function>jsonb_agg(<replaceable class="parameter">record</replaceable>)</function>

</entry>

<entry>

<type>record</type>

</entry>

<entry>

<type>jsonb</type>

</entry>

<entry>aggregates records as a JSON array of objects</entry>

</row>

<row>

<entry>

<indexterm>

<entry>aggregates name/value pairs as a JSON object</entry>

</row>

<row>

<entry>

<indexterm>

<primary>jsonb_object_agg</primary>

</indexterm>

<function>jsonb_object_agg(<replaceable class="parameter">name</replaceable>, <replaceable class="parameter">value</replaceable>)</function>

</entry>

<entry>

<type>("any", "any")</type>

</entry>

<entry>

<type>jsonb</type>

</entry>

<entry>aggregates name/value pairs as a JSON object</entry>

</row>

<row>

<entry>

<indexterm>

<para>

The aggregate functions <function>array_agg</function>,

<function>json_agg</function>,

<function>json_object_agg</function>,

<function>json_agg</function>, <function>jsonb_agg</function>,

<function>json_object_agg</function>, <function>jsonb_object_agg</function>,

<function>string_agg</function>,

and <function>xmlagg</function>, as well as similar user-defined

aggregate functions, produce meaningfully different result values

typoid=getBaseType(typoid);

getTypeOutputInfo(typoid,outfuncoid,&typisvarlena);

*outfuncoid=InvalidOid;

switch (typoid)

{

caseBOOLOID:

caseFLOAT4OID:

caseFLOAT8OID:

caseNUMERICOID:

getTypeOutputInfo(typoid,outfuncoid,&typisvarlena);

*tcategory=JSONTYPE_NUMERIC;

break;

caseJSONOID:

caseJSONBOID:

getTypeOutputInfo(typoid,outfuncoid,&typisvarlena);

*tcategory=JSONTYPE_JSON;

break;

if (typoid >=FirstNormalObjectId)

{

HeapTupletuple;

Oidcastfunc;

CoercionPathTypectype;

tuple=SearchSysCache2(CASTSOURCETARGET,

ObjectIdGetDatum(typoid),

ObjectIdGetDatum(JSONOID));

if (HeapTupleIsValid(tuple))

ctype=find_coercion_pathway(JSONOID,typoid,

COERCION_EXPLICIT,&castfunc);

if (ctype==COERCION_PATH_FUNC&&OidIsValid(castfunc))

{

Form_pg_castcastForm= (Form_pg_cast)GETSTRUCT(tuple);

if (castForm->castmethod==COERCION_METHOD_FUNCTION)

{

*tcategory=JSONTYPE_CAST;

*outfuncoid=castForm->castfunc;

}

ReleaseSysCache(tuple);

*tcategory=JSONTYPE_CAST;

*outfuncoid=castfunc;

}

{

getTypeOutputInfo(typoid,outfuncoid,&typisvarlena);

}

}

{

getTypeOutputInfo(typoid,outfuncoid,&typisvarlena);

}

}

break;