@ -105,6 +105,15 @@ static void populate_recordset_object_end(void *state);
static void populate_recordset_array_start ( void * state ) ;
static void populate_recordset_array_element_start ( void * state , bool isnull ) ;
/* semantic action functions for json_strip_nulls */
static void sn_object_start ( void * state ) ;
static void sn_object_end ( void * state ) ;
static void sn_array_start ( void * state ) ;
static void sn_array_end ( void * state ) ;
static void sn_object_field_start ( void * state , char * fname , bool isnull ) ;
static void sn_array_element_start ( void * state , bool isnull ) ;
static void sn_scalar ( void * state , char * token , JsonTokenType tokentype ) ;
/* worker function for populate_recordset and to_recordset */
static Datum populate_recordset_worker ( FunctionCallInfo fcinfo , const char * funcname ,
bool have_record_arg ) ;
@ -225,6 +234,13 @@ typedef struct PopulateRecordsetState
MemoryContext fn_mcxt ; /* used to stash IO funcs */
} PopulateRecordsetState ;
/* state for json_strip_nulls */
typedef struct StripnullState {
JsonLexContext * lex ;
StringInfo strval ;
bool skip_next_null ;
} StripnullState ;
/* Turn a jsonb object into a record */
static void make_row_from_rec_and_jsonb ( Jsonb * element ,
PopulateRecordsetState * state ) ;
@ -2996,3 +3012,184 @@ findJsonbValueFromContainerLen(JsonbContainer *container, uint32 flags,
return findJsonbValueFromContainer ( container , flags , & k ) ;
}
/*
* Semantic actions for json_strip_nulls .
*
* Simply repeat the input on the output unless we encounter
* a null object field . State for this is set when the field
* is started and reset when the scalar action ( which must be next )
* is called .
*/
static void
sn_object_start ( void * state )
{
StripnullState * _state = ( StripnullState * ) state ;
appendStringInfoCharMacro ( _state - > strval , ' { ' ) ;
}
static void
sn_object_end ( void * state )
{
StripnullState * _state = ( StripnullState * ) state ;
appendStringInfoCharMacro ( _state - > strval , ' } ' ) ;
}
static void
sn_array_start ( void * state )
{
StripnullState * _state = ( StripnullState * ) state ;
appendStringInfoCharMacro ( _state - > strval , ' [ ' ) ;
}
static void
sn_array_end ( void * state )
{
StripnullState * _state = ( StripnullState * ) state ;
appendStringInfoCharMacro ( _state - > strval , ' ] ' ) ;
}
static void
sn_object_field_start ( void * state , char * fname , bool isnull )
{
StripnullState * _state = ( StripnullState * ) state ;
if ( isnull )
{
/*
* The next thing must be a scalar or isnull couldn ' t be true ,
* so there is no danger of this state being carried down
* into a nested object or array . The flag will be reset in the
* scalar action .
*/
_state - > skip_next_null = true ;
return ;
}
if ( _state - > strval - > data [ _state - > strval - > len - 1 ] ! = ' { ' )
appendStringInfoCharMacro ( _state - > strval , ' , ' ) ;
/*
* Unfortunately we don ' t have the quoted and escaped string any more ,
* so we have to re - escape it .
*/
escape_json ( _state - > strval , fname ) ;
appendStringInfoCharMacro ( _state - > strval , ' : ' ) ;
}
static void
sn_array_element_start ( void * state , bool isnull )
{
StripnullState * _state = ( StripnullState * ) state ;
if ( _state - > strval - > data [ _state - > strval - > len - 1 ] ! = ' [ ' )
appendStringInfoCharMacro ( _state - > strval , ' , ' ) ;
}
static void
sn_scalar ( void * state , char * token , JsonTokenType tokentype )
{
StripnullState * _state = ( StripnullState * ) state ;
if ( _state - > skip_next_null )
{
Assert ( tokentype = = JSON_TOKEN_NULL ) ;
_state - > skip_next_null = false ;
return ;
}
if ( tokentype = = JSON_TOKEN_STRING )
escape_json ( _state - > strval , token ) ;
else
appendStringInfoString ( _state - > strval , token ) ;
}
/*
* SQL function json_strip_nulls ( json ) - > json
*/
Datum
json_strip_nulls ( PG_FUNCTION_ARGS )
{
text * json = PG_GETARG_TEXT_P ( 0 ) ;
StripnullState * state ;
JsonLexContext * lex ;
JsonSemAction * sem ;
lex = makeJsonLexContext ( json , true ) ;
state = palloc0 ( sizeof ( StripnullState ) ) ;
sem = palloc0 ( sizeof ( JsonSemAction ) ) ;
state - > strval = makeStringInfo ( ) ;
state - > skip_next_null = false ;
state - > lex = lex ;
sem - > semstate = ( void * ) state ;
sem - > object_start = sn_object_start ;
sem - > object_end = sn_object_end ;
sem - > array_start = sn_array_start ;
sem - > array_end = sn_array_end ;
sem - > scalar = sn_scalar ;
sem - > array_element_start = sn_array_element_start ;
sem - > object_field_start = sn_object_field_start ;
pg_parse_json ( lex , sem ) ;
PG_RETURN_TEXT_P ( cstring_to_text_with_len ( state - > strval - > data ,
state - > strval - > len ) ) ;
}
/*
* SQL function jsonb_strip_nulls ( jsonb ) - > jsonb
*/
Datum
jsonb_strip_nulls ( PG_FUNCTION_ARGS )
{
Jsonb * jb = PG_GETARG_JSONB ( 0 ) ;
JsonbIterator * it ;
JsonbParseState * parseState = NULL ;
JsonbValue * res = NULL ;
int type ;
JsonbValue v , k ;
bool last_was_key = false ;
if ( JB_ROOT_IS_SCALAR ( jb ) )
PG_RETURN_POINTER ( jb ) ;
it = JsonbIteratorInit ( & jb - > root ) ;
while ( ( type = JsonbIteratorNext ( & it , & v , false ) ) ! = WJB_DONE )
{
Assert ( ! ( type = = WJB_KEY & & last_was_key ) ) ;
if ( type = = WJB_KEY )
{
/* stash the key until we know if it has a null value */
k = v ;
last_was_key = true ;
continue ;
}
if ( last_was_key )
{
/* if the last element was a key this one can't be */
last_was_key = false ;
/* skip this field if value is null */
if ( type = = WJB_VALUE & & v . type = = jbvNull )
continue ;
/* otherwise, do a delayed push of the key */
res = pushJsonbValue ( & parseState , WJB_KEY , & k ) ;
}
if ( type = = WJB_VALUE | | type = = WJB_ELEM )
res = pushJsonbValue ( & parseState , type , & v ) ;
else
res = pushJsonbValue ( & parseState , type , NULL ) ;
}
PG_RETURN_POINTER ( JsonbValueToJsonb ( res ) ) ;
}
Andrew Dunstan
11 years ago