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Commitc80b992

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committed
Transform or iterate over json(b) string values
Dmitry Dolgov, reviewed and lightly edited by me.
1 parent156d388 commitc80b992

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2 files changed

+252
-0
lines changed

2 files changed

+252
-0
lines changed

‎src/backend/utils/adt/jsonfuncs.c

Lines changed: 236 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -52,6 +52,25 @@ typedef struct OkeysState
5252
intsent_count;
5353
}OkeysState;
5454

55+
/* state for iterate_json_string_values function */
56+
typedefstructIterateJsonStringValuesState
57+
{
58+
JsonLexContext*lex;
59+
JsonIterateStringValuesActionaction;/* an action that will be applied
60+
to each json value */
61+
void*action_state;/* any necessary context for iteration */
62+
}IterateJsonStringValuesState;
63+
64+
/* state for transform_json_string_values function */
65+
typedefstructTransformJsonStringValuesState
66+
{
67+
JsonLexContext*lex;
68+
StringInfostrval;/* resulting json */
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JsonTransformStringValuesActionaction;/* an action that will be applied
70+
to each json value */
71+
void*action_state;/* any necessary context for transformation */
72+
}TransformJsonStringValuesState;
73+
5574
/* state for json_get* functions */
5675
typedefstructGetState
5776
{
@@ -271,6 +290,18 @@ static void setPathArray(JsonbIterator **it, Datum *path_elems,
271290
intlevel,Jsonb*newval,uint32nelems,intop_type);
272291
staticvoidaddJsonbToParseState(JsonbParseState**jbps,Jsonb*jb);
273292

293+
/* function supporting iterate_json_string_values */
294+
staticvoiditerate_string_values_scalar(void*state,char*token,JsonTokenTypetokentype);
295+
296+
/* functions supporting transform_json_string_values */
297+
staticvoidtransform_string_values_object_start(void*state);
298+
staticvoidtransform_string_values_object_end(void*state);
299+
staticvoidtransform_string_values_array_start(void*state);
300+
staticvoidtransform_string_values_array_end(void*state);
301+
staticvoidtransform_string_values_object_field_start(void*state,char*fname,boolisnull);
302+
staticvoidtransform_string_values_array_element_start(void*state,boolisnull);
303+
staticvoidtransform_string_values_scalar(void*state,char*token,JsonTokenTypetokentype);
304+
274305

275306
/*
276307
* SQL function json_object_keys
@@ -4130,3 +4161,208 @@ setPathArray(JsonbIterator **it, Datum *path_elems, bool *path_nulls,
41304161
}
41314162
}
41324163
}
4164+
4165+
/*
4166+
* Iterate over jsonb string values or elements, and pass them together with an
4167+
* iteration state to a specified JsonIterateStringValuesAction.
4168+
*/
4169+
void
4170+
iterate_jsonb_string_values(Jsonb*jb,void*state,JsonIterateStringValuesActionaction)
4171+
{
4172+
JsonbIterator*it;
4173+
JsonbValuev;
4174+
JsonbIteratorTokentype;
4175+
4176+
it=JsonbIteratorInit(&jb->root);
4177+
4178+
while ((type=JsonbIteratorNext(&it,&v, false))!=WJB_DONE)
4179+
{
4180+
if ((type==WJB_VALUE||type==WJB_ELEM)&&v.type==jbvString)
4181+
{
4182+
action(state,v.val.string.val,v.val.string.len);
4183+
}
4184+
}
4185+
}
4186+
4187+
/*
4188+
* Iterate over json string values or elements, and pass them together with an
4189+
* iteration state to a specified JsonIterateStringValuesAction.
4190+
*/
4191+
void
4192+
iterate_json_string_values(text*json,void*action_state,JsonIterateStringValuesActionaction)
4193+
{
4194+
JsonLexContext*lex=makeJsonLexContext(json, true);
4195+
JsonSemAction*sem=palloc0(sizeof(JsonSemAction));
4196+
IterateJsonStringValuesState*state=palloc0(sizeof(IterateJsonStringValuesState));
4197+
4198+
state->lex=lex;
4199+
state->action=action;
4200+
state->action_state=action_state;
4201+
4202+
sem->semstate= (void*)state;
4203+
sem->scalar=iterate_string_values_scalar;
4204+
4205+
pg_parse_json(lex,sem);
4206+
}
4207+
4208+
/*
4209+
* An auxiliary function for iterate_json_string_values to invoke a specified
4210+
* JsonIterateStringValuesAction.
4211+
*/
4212+
staticvoid
4213+
iterate_string_values_scalar(void*state,char*token,JsonTokenTypetokentype)
4214+
{
4215+
IterateJsonStringValuesState*_state= (IterateJsonStringValuesState*)state;
4216+
if (tokentype==JSON_TOKEN_STRING)
4217+
(*_state->action) (_state->action_state,token,strlen(token));
4218+
}
4219+
4220+
/*
4221+
* Iterate over a jsonb, and apply a specified JsonTransformStringValuesAction
4222+
* to every string value or element. Any necessary context for a
4223+
* JsonTransformStringValuesAction can be passed in the action_state variable.
4224+
* Function returns a copy of an original jsonb object with transformed values.
4225+
*/
4226+
Jsonb*
4227+
transform_jsonb_string_values(Jsonb*jsonb,void*action_state,
4228+
JsonTransformStringValuesActiontransform_action)
4229+
{
4230+
JsonbIterator*it;
4231+
JsonbValuev,*res=NULL;
4232+
JsonbIteratorTokentype;
4233+
JsonbParseState*st=NULL;
4234+
text*out;
4235+
boolis_scalar= false;
4236+
4237+
it=JsonbIteratorInit(&jsonb->root);
4238+
is_scalar=it->isScalar;
4239+
4240+
while ((type=JsonbIteratorNext(&it,&v, false))!=WJB_DONE)
4241+
{
4242+
if ((type==WJB_VALUE||type==WJB_ELEM)&&v.type==jbvString)
4243+
{
4244+
out=transform_action(action_state,v.val.string.val,v.val.string.len);
4245+
v.val.string.val=VARDATA_ANY(out);
4246+
v.val.string.len=VARSIZE_ANY_EXHDR(out);
4247+
res=pushJsonbValue(&st,type,type<WJB_BEGIN_ARRAY ?&v :NULL);
4248+
}
4249+
else
4250+
{
4251+
res=pushJsonbValue(&st,type, (type==WJB_KEY||
4252+
type==WJB_VALUE||
4253+
type==WJB_ELEM) ?&v :NULL);
4254+
}
4255+
}
4256+
4257+
if (res->type==jbvArray)
4258+
res->val.array.rawScalar=is_scalar;
4259+
4260+
returnJsonbValueToJsonb(res);
4261+
}
4262+
4263+
/*
4264+
* Iterate over a json, and apply a specified JsonTransformStringValuesAction
4265+
* to every string value or element. Any necessary context for a
4266+
* JsonTransformStringValuesAction can be passed in the action_state variable.
4267+
* Function returns a StringInfo, which is a copy of an original json with
4268+
* transformed values.
4269+
*/
4270+
text*
4271+
transform_json_string_values(text*json,void*action_state,
4272+
JsonTransformStringValuesActiontransform_action)
4273+
{
4274+
JsonLexContext*lex=makeJsonLexContext(json, true);
4275+
JsonSemAction*sem=palloc0(sizeof(JsonSemAction));
4276+
TransformJsonStringValuesState*state=palloc0(sizeof(TransformJsonStringValuesState));
4277+
4278+
state->lex=lex;
4279+
state->strval=makeStringInfo();
4280+
state->action=transform_action;
4281+
state->action_state=action_state;
4282+
4283+
sem->semstate= (void*)state;
4284+
sem->scalar=transform_string_values_scalar;
4285+
sem->object_start=transform_string_values_object_start;
4286+
sem->object_end=transform_string_values_object_end;
4287+
sem->array_start=transform_string_values_array_start;
4288+
sem->array_end=transform_string_values_array_end;
4289+
sem->scalar=transform_string_values_scalar;
4290+
sem->array_element_start=transform_string_values_array_element_start;
4291+
sem->object_field_start=transform_string_values_object_field_start;
4292+
4293+
pg_parse_json(lex,sem);
4294+
4295+
returncstring_to_text_with_len(state->strval->data,state->strval->len);
4296+
}
4297+
4298+
/*
4299+
* Set of auxiliary functions for transform_json_string_values to invoke a
4300+
* specified JsonTransformStringValuesAction for all values and left everything
4301+
* else untouched.
4302+
*/
4303+
staticvoid
4304+
transform_string_values_object_start(void*state)
4305+
{
4306+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4307+
appendStringInfoCharMacro(_state->strval,'{');
4308+
}
4309+
4310+
staticvoid
4311+
transform_string_values_object_end(void*state)
4312+
{
4313+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4314+
appendStringInfoCharMacro(_state->strval,'}');
4315+
}
4316+
4317+
staticvoid
4318+
transform_string_values_array_start(void*state)
4319+
{
4320+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4321+
appendStringInfoCharMacro(_state->strval,'[');
4322+
}
4323+
4324+
staticvoid
4325+
transform_string_values_array_end(void*state)
4326+
{
4327+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4328+
appendStringInfoCharMacro(_state->strval,']');
4329+
}
4330+
4331+
staticvoid
4332+
transform_string_values_object_field_start(void*state,char*fname,boolisnull)
4333+
{
4334+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4335+
4336+
if (_state->strval->data[_state->strval->len-1]!='{')
4337+
appendStringInfoCharMacro(_state->strval,',');
4338+
4339+
/*
4340+
* Unfortunately we don't have the quoted and escaped string any more, so
4341+
* we have to re-escape it.
4342+
*/
4343+
escape_json(_state->strval,fname);
4344+
appendStringInfoCharMacro(_state->strval,':');
4345+
}
4346+
4347+
staticvoid
4348+
transform_string_values_array_element_start(void*state,boolisnull)
4349+
{
4350+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4351+
4352+
if (_state->strval->data[_state->strval->len-1]!='[')
4353+
appendStringInfoCharMacro(_state->strval,',');
4354+
}
4355+
4356+
staticvoid
4357+
transform_string_values_scalar(void*state,char*token,JsonTokenTypetokentype)
4358+
{
4359+
TransformJsonStringValuesState*_state= (TransformJsonStringValuesState*)state;
4360+
4361+
if (tokentype==JSON_TOKEN_STRING)
4362+
{
4363+
text*out= (*_state->action) (_state->action_state,token,strlen(token));
4364+
escape_json(_state->strval,text_to_cstring(out));
4365+
}
4366+
else
4367+
appendStringInfoString(_state->strval,token);
4368+
}

‎src/include/utils/jsonapi.h

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@
1414
#ifndefJSONAPI_H
1515
#defineJSONAPI_H
1616

17+
#include"jsonb.h"
1718
#include"lib/stringinfo.h"
1819

1920
typedefenum
@@ -131,4 +132,19 @@ extern JsonLexContext *makeJsonLexContextCstringLen(char *json,
131132
*/
132133
externboolIsValidJsonNumber(constchar*str,intlen);
133134

135+
/* an action that will be applied to each value in iterate_json(b)_string_vaues functions */
136+
typedefvoid (*JsonIterateStringValuesAction) (void*state,char*elem_value,intelem_len);
137+
138+
/* an action that will be applied to each value in transform_json(b)_string_values functions */
139+
typedeftext* (*JsonTransformStringValuesAction) (void*state,char*elem_value,intelem_len);
140+
141+
externvoiditerate_jsonb_string_values(Jsonb*jb,void*state,
142+
JsonIterateStringValuesActionaction);
143+
externvoiditerate_json_string_values(text*json,void*action_state,
144+
JsonIterateStringValuesActionaction);
145+
externJsonb*transform_jsonb_string_values(Jsonb*jsonb,void*action_state,
146+
JsonTransformStringValuesActiontransform_action);
147+
externtext*transform_json_string_values(text*json,void*action_state,
148+
JsonTransformStringValuesActiontransform_action);
149+
134150
#endif/* JSONAPI_H */

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