json_typeof function.
Andrew Tipton.
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@ -10095,7 +10095,7 @@ table2-mapping
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</entry>
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<entry><type>json</type></entry>
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<entry>
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Returns JSON object pointed to by <parameter>path_elems</parameter>.
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Returns JSON value pointed to by <parameter>path_elems</parameter>.
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</entry>
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<entry><literal>json_extract_path('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}','f4')</literal></entry>
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<entry><literal>{"f5":99,"f6":"foo"}</literal></entry>
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@ -10109,7 +10109,7 @@ table2-mapping
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</entry>
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<entry><type>text</type></entry>
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<entry>
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Returns JSON object pointed to by <parameter>path_elems</parameter>.
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Returns JSON value pointed to by <parameter>path_elems</parameter>.
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</entry>
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<entry><literal>json_extract_path_text('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}','f4', 'f6')</literal></entry>
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<entry><literal>foo</literal></entry>
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@ -10192,7 +10192,7 @@ table2-mapping
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</entry>
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<entry><type>SETOF json</type></entry>
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<entry>
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Expands a JSON array to a set of JSON elements.
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Expands a JSON array to a set of JSON values.
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</entry>
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<entry><literal>json_array_elements('[1,true, [2,false]]')</literal></entry>
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<entry>
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@ -10205,6 +10205,23 @@ table2-mapping
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</programlisting>
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</entry>
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</row>
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<row>
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<entry>
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<indexterm>
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<primary>json_typeof</primary>
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</indexterm>
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<literal>json_typeof(json)</literal>
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</entry>
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<entry><type>text</type></entry>
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<entry>
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Returns the type of the outermost JSON value as a text string. The types are
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<literal>object</>, <literal>array</>, <literal>string</>, <literal>number</>,
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<literal>boolean</>, and <literal>null</>. (See note below regarding the
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distinction between a JSON <literal>null</> and a SQL NULL.)
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</entry>
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<entry><literal>json_typeof('-123.4')</literal></entry>
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<entry><literal>number</literal></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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@ -10237,6 +10254,14 @@ table2-mapping
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</para>
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</note>
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<note>
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<para>
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The <literal>json_typeof</> function's <literal>null</> return value should not be confused
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with a SQL NULL. While calling <literal>json_typeof('null'::json)</> will return <literal>null</>,
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calling <literal>json_typeof(NULL::json)</> will return a SQL NULL.
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</para>
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</note>
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<para>
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See also <xref linkend="functions-aggregate"> about the aggregate
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function <function>json_agg</function> which aggregates record
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@ -1826,3 +1826,55 @@ escape_json(StringInfo buf, const char *str)
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}
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appendStringInfoCharMacro(buf, '\"');
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}
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/*
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* SQL function json_typeof(json) -> text
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*
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* Returns the type of the outermost JSON value as TEXT. Possible types are
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* "object", "array", "string", "number", "boolean", and "null".
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*
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* Performs a single call to json_lex() to get the first token of the supplied
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* value. This initial token uniquely determines the value's type. As our
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* input must already have been validated by json_in() or json_recv(), the
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* initial token should never be JSON_TOKEN_OBJECT_END, JSON_TOKEN_ARRAY_END,
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* JSON_TOKEN_COLON, JSON_TOKEN_COMMA, or JSON_TOKEN_END.
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*/
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Datum
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json_typeof(PG_FUNCTION_ARGS)
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{
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text *json = PG_GETARG_TEXT_P(0);
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JsonLexContext *lex = makeJsonLexContext(json, false);
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JsonTokenType tok;
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char *type;
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/* Lex exactly one token from the input and check its type. */
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json_lex(lex);
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tok = lex_peek(lex);
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switch (tok)
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{
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case JSON_TOKEN_OBJECT_START:
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type = "object";
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break;
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case JSON_TOKEN_ARRAY_START:
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type = "array";
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break;
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case JSON_TOKEN_STRING:
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type = "string";
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break;
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case JSON_TOKEN_NUMBER:
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type = "number";
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break;
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case JSON_TOKEN_TRUE:
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case JSON_TOKEN_FALSE:
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type = "boolean";
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break;
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case JSON_TOKEN_NULL:
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type = "null";
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break;
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default:
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elog(ERROR, "unexpected json token: %d", tok);
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}
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PG_RETURN_TEXT_P(cstring_to_text(type));
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}
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@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 201310091
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#define CATALOG_VERSION_NO 201310101
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#endif
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@ -4150,6 +4150,8 @@ DATA(insert OID = 3960 ( json_populate_record PGNSP PGUID 12 1 0 0 0 f f f f
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DESCR("get record fields from a json object");
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DATA(insert OID = 3961 ( json_populate_recordset PGNSP PGUID 12 1 100 0 0 f f f f f t s 3 0 2283 "2283 114 16" _null_ _null_ _null_ _null_ json_populate_recordset _null_ _null_ _null_ ));
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DESCR("get set of records with fields from a json array of objects");
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DATA(insert OID = 3968 ( json_typeof PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 25 "114" _null_ _null_ _null_ _null_ json_typeof _null_ _null_ _null_ ));
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DESCR("get the type of a json value");
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/* uuid */
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DATA(insert OID = 2952 ( uuid_in PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 2950 "2275" _null_ _null_ _null_ _null_ uuid_in _null_ _null_ _null_ ));
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@ -33,6 +33,8 @@ extern Datum json_agg_finalfn(PG_FUNCTION_ARGS);
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extern void escape_json(StringInfo buf, const char *str);
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extern Datum json_typeof(PG_FUNCTION_ARGS);
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/* functions in jsonfuncs.c */
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extern Datum json_object_field(PG_FUNCTION_ARGS);
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extern Datum json_object_field_text(PG_FUNCTION_ARGS);
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@ -962,3 +962,32 @@ select json '{ "a": "null \u0000 escape" }' ->> 'a' as not_unescaped;
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null \u0000 escape
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(1 row)
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--json_typeof() function
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select value, json_typeof(value)
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from (values (json '123.4'),
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(json '-1'),
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(json '"foo"'),
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(json 'true'),
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(json 'false'),
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(json 'null'),
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(json '[1, 2, 3]'),
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(json '[]'),
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(json '{"x":"foo", "y":123}'),
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(json '{}'),
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(NULL::json))
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as data(value);
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value | json_typeof
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----------------------+-------------
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123.4 | number
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-1 | number
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"foo" | string
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true | boolean
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false | boolean
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null | null
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[1, 2, 3] | array
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[] | array
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{"x":"foo", "y":123} | object
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{} | object
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(11 rows)
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@ -958,3 +958,32 @@ select json '{ "a": "null \u0000 escape" }' ->> 'a' as not_unescaped;
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null \u0000 escape
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(1 row)
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--json_typeof() function
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select value, json_typeof(value)
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from (values (json '123.4'),
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(json '-1'),
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(json '"foo"'),
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(json 'true'),
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(json 'false'),
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(json 'null'),
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(json '[1, 2, 3]'),
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(json '[]'),
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(json '{"x":"foo", "y":123}'),
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(json '{}'),
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(NULL::json))
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as data(value);
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value | json_typeof
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----------------------+-------------
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123.4 | number
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-1 | number
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"foo" | string
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true | boolean
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false | boolean
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null | null
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[1, 2, 3] | array
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[] | array
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{"x":"foo", "y":123} | object
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{} | object
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(11 rows)
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@ -310,3 +310,18 @@ select json '{ "a": "\ude04X" }' -> 'a'; -- orphan low surrogate
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select json '{ "a": "the Copyright \u00a9 sign" }' ->> 'a' as correct_in_utf8;
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select json '{ "a": "dollar \u0024 character" }' ->> 'a' as correct_everywhere;
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select json '{ "a": "null \u0000 escape" }' ->> 'a' as not_unescaped;
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--json_typeof() function
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select value, json_typeof(value)
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from (values (json '123.4'),
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(json '-1'),
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(json '"foo"'),
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(json 'true'),
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(json 'false'),
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(json 'null'),
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(json '[1, 2, 3]'),
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(json '[]'),
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(json '{"x":"foo", "y":123}'),
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(json '{}'),
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(NULL::json))
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as data(value);
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