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This introduces the SQL/JSON functions for querying JSON data using jsonpath expressions. The functions are: JSON_EXISTS() JSON_QUERY() JSON_VALUE() All of these functions only operate on jsonb. The workaround for now is to cast the argument to jsonb. JSON_EXISTS() tests if the jsonpath expression applied to the jsonb value yields any values. JSON_VALUE() must return a single value, and an error occurs if it tries to return multiple values. JSON_QUERY() must return a json object or array, and there are various WRAPPER options for handling scalar or multi-value results. Both these functions have options for handling EMPTY and ERROR conditions. Nikita Glukhov Reviewers have included (in no particular order) Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby. Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
65 lines
2.3 KiB
C
65 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* jsonfuncs.h
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* Functions to process JSON data types.
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*
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* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/jsonfuncs.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef JSONFUNCS_H
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#define JSONFUNCS_H
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#include "common/jsonapi.h"
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#include "utils/jsonb.h"
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/*
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* Flag types for iterate_json(b)_values to specify what elements from a
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* json(b) document we want to iterate.
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*/
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typedef enum JsonToIndex
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{
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jtiKey = 0x01,
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jtiString = 0x02,
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jtiNumeric = 0x04,
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jtiBool = 0x08,
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jtiAll = jtiKey | jtiString | jtiNumeric | jtiBool
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} JsonToIndex;
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/* an action that will be applied to each value in iterate_json(b)_values functions */
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typedef void (*JsonIterateStringValuesAction) (void *state, char *elem_value, int elem_len);
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/* an action that will be applied to each value in transform_json(b)_values functions */
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typedef text *(*JsonTransformStringValuesAction) (void *state, char *elem_value, int elem_len);
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/* build a JsonLexContext from a text datum */
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extern JsonLexContext *makeJsonLexContext(text *json, bool need_escapes);
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/* try to parse json, and ereport(ERROR) on failure */
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extern void pg_parse_json_or_ereport(JsonLexContext *lex, JsonSemAction *sem);
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/* report an error during json lexing or parsing */
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extern void json_ereport_error(JsonParseErrorType error, JsonLexContext *lex);
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/* get first JSON token */
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extern JsonTokenType json_get_first_token(text *json, bool throw_error);
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extern uint32 parse_jsonb_index_flags(Jsonb *jb);
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extern void iterate_jsonb_values(Jsonb *jb, uint32 flags, void *state,
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JsonIterateStringValuesAction action);
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extern void iterate_json_values(text *json, uint32 flags, void *action_state,
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JsonIterateStringValuesAction action);
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extern Jsonb *transform_jsonb_string_values(Jsonb *jsonb, void *action_state,
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JsonTransformStringValuesAction transform_action);
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extern text *transform_json_string_values(text *json, void *action_state,
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JsonTransformStringValuesAction transform_action);
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extern Datum json_populate_type(Datum json_val, Oid json_type,
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Oid typid, int32 typmod,
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void **cache, MemoryContext mcxt, bool *isnull);
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#endif
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