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Add json_array_elements_text function.

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This was a notable omission from the json functions added in 9.3 and
there have been numerous complaints about its absence.

Laurence Rowe.
This commit is contained in:
Andrew Dunstan
2014-01-29 15:39:01 -05:00
parent 699b1f40da
commit 5264d91541
7 changed files with 143 additions and 22 deletions
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67
src/backend/utils/adt/jsonfuncs.c
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@ -66,6 +66,9 @@ static void each_object_field_end(void *state, char *fname, bool isnull);
static void each_array_start(void *state);
static void each_scalar(void *state, char *token, JsonTokenType tokentype);
/* common worker for json_each* functions */
static inline Datum elements_worker(PG_FUNCTION_ARGS, bool as_text);
/* semantic action functions for json_array_elements */
static void elements_object_start(void *state);
static void elements_array_element_start(void *state, bool isnull);
@ -165,6 +168,9 @@ typedef struct ElementsState
TupleDesc ret_tdesc;
MemoryContext tmp_cxt;
char *result_start;
bool normalize_results;
bool next_scalar;
char *normalized_scalar;
} ElementsState;
/* state for get_json_object_as_hash */
@ -1069,7 +1075,7 @@ each_scalar(void *state, char *token, JsonTokenType tokentype)
}
/*
* SQL function json_array_elements
* SQL functions json_array_elements and json_array_elements_text
*
* get the elements from a json array
*
@ -1077,11 +1083,23 @@ each_scalar(void *state, char *token, JsonTokenType tokentype)
*/
Datum
json_array_elements(PG_FUNCTION_ARGS)
{
return elements_worker(fcinfo, false);
}
Datum
json_array_elements_text(PG_FUNCTION_ARGS)
{
return elements_worker(fcinfo, true);
}
static inline Datum
elements_worker(PG_FUNCTION_ARGS, bool as_text)
{
text *json = PG_GETARG_TEXT_P(0);
/* elements doesn't need any escaped strings, so use false here */
JsonLexContext *lex = makeJsonLexContext(json, false);
/* elements only needs escaped strings when as_text */
JsonLexContext *lex = makeJsonLexContext(json, as_text);
JsonSemAction *sem;
ReturnSetInfo *rsi;
MemoryContext old_cxt;
@ -1124,6 +1142,9 @@ json_array_elements(PG_FUNCTION_ARGS)
sem->array_element_start = elements_array_element_start;
sem->array_element_end = elements_array_element_end;
state->normalize_results = as_text;
state->next_scalar = false;
state->lex = lex;
state->tmp_cxt = AllocSetContextCreate(CurrentMemoryContext,
"json_array_elements temporary cxt",
@ -1146,7 +1167,17 @@ elements_array_element_start(void *state, bool isnull)
/* save a pointer to where the value starts */
if (_state->lex->lex_level == 1)
_state->result_start = _state->lex->token_start;
{
/*
* next_scalar will be reset in the array_element_end handler, and
* since we know the value is a scalar there is no danger of it being
* on while recursing down the tree.
*/
if (_state->normalize_results && _state->lex->token_type == JSON_TOKEN_STRING)
_state->next_scalar = true;
else
_state->result_start = _state->lex->token_start;
}
}
static void
@ -1158,7 +1189,7 @@ elements_array_element_end(void *state, bool isnull)
text *val;
HeapTuple tuple;
Datum values[1];
static bool nulls[1] = {false};
bool nulls[1] = {false};
/* skip over nested objects */
if (_state->lex->lex_level != 1)
@ -1167,10 +1198,23 @@ elements_array_element_end(void *state, bool isnull)
/* use the tmp context so we can clean up after each tuple is done */
old_cxt = MemoryContextSwitchTo(_state->tmp_cxt);
len = _state->lex->prev_token_terminator - _state->result_start;
val = cstring_to_text_with_len(_state->result_start, len);
if (isnull && _state->normalize_results)
{
nulls[0] = true;
values[0] = (Datum) NULL;
}
else if (_state->next_scalar)
{
values[0] = CStringGetTextDatum(_state->normalized_scalar);
_state->next_scalar = false;
}
else
{
len = _state->lex->prev_token_terminator - _state->result_start;
val = cstring_to_text_with_len(_state->result_start, len);
values[0] = PointerGetDatum(val);
}
values[0] = PointerGetDatum(val);
tuple = heap_form_tuple(_state->ret_tdesc, values, nulls);
@ -1204,10 +1248,9 @@ elements_scalar(void *state, char *token, JsonTokenType tokentype)
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("cannot call json_array_elements on a scalar")));
/*
* json_array_elements always returns json, so there's no need to think
* about de-escaped values here.
*/
/* supply de-escaped value if required */
if (_state->next_scalar)
_state->normalized_scalar = token;
}
/*