Re: [HACKERS] strip nulls functions for json and jsonb

[Pavel Stehule]

Hi

I am sending a final review of this patch:

0. this patch implements null fields stripping. It does exactly what was
proposed and we would to have this feature in core. It is requested feature
for JSON types.

1. there is no problem with patch apply and with compilation - one warning
is fixed in attachments

2. code is relative small and clean, I have no any objection

3. there is necessary regress tests and related documentation.


I have no any objection - this patch is ready for commiter.

Thank you for patch

Regards

Pavel

2014-10-26 21:57 GMT+01:00 Andrew Dunstan :

>
> On 10/26/2014 04:22 PM, Pavel Stehule wrote:
>
>>
>>
>> 2014-10-26 21:18 GMT+01:00 Andrew Dunstan > and...@dunslane.net>>:
>>
>>
>> On 10/26/2014 04:14 PM, Thom Brown wrote:
>>
>> On 26 October 2014 20:07, Andrew Dunstan >  > >> wrote:
>>
>>
>> On 10/26/2014 03:50 PM, Pavel Stehule wrote:
>>
>> Hi
>>
>> I have a question,
>>
>> what is expected result of null strip of
>>
>> {"a": {"b": null, "c", null"} }
>>
>> ?
>>
>>
>>
>> Please remember not to top-post.
>>
>> The above is not legal json, so the answer would be an error.
>>
>>
>> I believe Pavel means:
>>
>> {"a": {"b": null, "c": null} }
>>
>>
>> This is the expected result:
>>
>>andrew=# select json_strip_nulls('{"a": {"b": null, "c": null} }');
>>  json_strip_nulls
>>--
>>  {"a":{}}
>>(1 row)
>>
>>
>> It is NOT expected that we replace an empty object with NULL (and
>> then strip it if it's a field value of an outer level object).
>>
>>
>> ok,
>>
>> This case should be in regress test probably
>>
>>
>>
> Patch attached.
>
> cheers
>
> andrew
>
commit 03dc02f601c6b9097402317e2dfa34e0f5d33ba5
Author: Pavel Stehule 
Date:   Mon Oct 27 10:53:55 2014 +0100

initial

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index f59738a..e453da4 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10716,6 +10716,19 @@ table2-mapping
 

   
+  
+   json_strip_nulls(from_json json)
+ jsonb_strip_nulls(from_json jsonb)
+   
+   jsonjsonb
+   
+ Returns from_json
+ with all object fields that have null values omitted. Other null values
+ are untouched.
+   
+   json_strip_nulls('[{"f1":1,"f2":null},2,null,3]')
+   [{"f1":1},2,null,3]
+   
  
 

@@ -10752,6 +10765,16 @@ table2-mapping
 
   
 
+  
+
+  If the argument to json_strip_nulls contains duplicate
+  field names in any object, the result could be semantically somewhat
+  different, depending on the order in which they occur. This is not an
+  issue for jsonb_strip_nulls since jsonb values never have
+  duplicate object field names.
+
+  
+
   
 See also  for the aggregate
 function json_agg which aggregates record
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 2d00dbe..efbec7f 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -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.
+ *

Re: [HACKERS] strip nulls functions for json and jsonb

[Andrew Dunstan]

On 10/26/2014 04:22 PM, Pavel Stehule wrote:



2014-10-26 21:18 GMT+01:00 Andrew Dunstan >:



On 10/26/2014 04:14 PM, Thom Brown wrote:

On 26 October 2014 20:07, Andrew Dunstan mailto:and...@dunslane.net> >> wrote:


On 10/26/2014 03:50 PM, Pavel Stehule wrote:

Hi

I have a question,

what is expected result of null strip of

{"a": {"b": null, "c", null"} }

?



Please remember not to top-post.

The above is not legal json, so the answer would be an error.


I believe Pavel means:

{"a": {"b": null, "c": null} }


This is the expected result:

   andrew=# select json_strip_nulls('{"a": {"b": null, "c": null} }');
 json_strip_nulls
   --
 {"a":{}}
   (1 row)


It is NOT expected that we replace an empty object with NULL (and
then strip it if it's a field value of an outer level object).


ok,

This case should be in regress test probably




Patch attached.

cheers

andrew
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 7e5bcd9..352b408 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10716,6 +10716,19 @@ table2-mapping
 

   
+  
+   json_strip_nulls(from_json json)
+ jsonb_strip_nulls(from_json jsonb)
+   
+   jsonjsonb
+   
+ Returns from_json
+ with all object fields that have null values omitted. Other null values
+ are untouched.
+   
+   json_strip_nulls('[{"f1":1,"f2":null},2,null,3]')
+   [{"f1":1},2,null,3]
+   
  
 

@@ -10752,6 +10765,16 @@ table2-mapping
 
   
 
+  
+
+  If the argument to json_strip_nulls contains duplicate
+  field names in any object, the result could be semantically somewhat
+  different, depending on the order in which they occur. This is not an
+  issue for jsonb_strip_nulls since jsonb values never have
+  duplicate object field names.
+
+  
+
   
 See also  for the aggregate
 function json_agg which aggregates record
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 2d00dbe..06db3e4 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -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

Re: [HACKERS] strip nulls functions for json and jsonb

[Andrew Dunstan]

On 10/26/2014 04:14 PM, Thom Brown wrote:
On 26 October 2014 20:07, Andrew Dunstan > wrote:



On 10/26/2014 03:50 PM, Pavel Stehule wrote:

Hi

I have a question,

what is expected result of null strip of

{"a": {"b": null, "c", null"} }

?



Please remember not to top-post.

The above is not legal json, so the answer would be an error.


I believe Pavel means:

{"a": {"b": null, "c": null} }


This is the expected result:

   andrew=# select json_strip_nulls('{"a": {"b": null, "c": null} }');
 json_strip_nulls
   --
 {"a":{}}
   (1 row)


It is NOT expected that we replace an empty object with NULL (and then 
strip it if it's a field value of an outer level object).


cheers

andrew



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Re: [HACKERS] strip nulls functions for json and jsonb

[Pavel Stehule]

2014-10-26 21:18 GMT+01:00 Andrew Dunstan :

>
> On 10/26/2014 04:14 PM, Thom Brown wrote:
>
>> On 26 October 2014 20:07, Andrew Dunstan > and...@dunslane.net>> wrote:
>>
>>
>> On 10/26/2014 03:50 PM, Pavel Stehule wrote:
>>
>> Hi
>>
>> I have a question,
>>
>> what is expected result of null strip of
>>
>> {"a": {"b": null, "c", null"} }
>>
>> ?
>>
>>
>>
>> Please remember not to top-post.
>>
>> The above is not legal json, so the answer would be an error.
>>
>>
>> I believe Pavel means:
>>
>> {"a": {"b": null, "c": null} }
>>
>
> This is the expected result:
>
>andrew=# select json_strip_nulls('{"a": {"b": null, "c": null} }');
>  json_strip_nulls
>--
>  {"a":{}}
>(1 row)
>
>
> It is NOT expected that we replace an empty object with NULL (and then
> strip it if it's a field value of an outer level object).
>

ok,

This case should be in regress test probably

Thank you

Pavel


>
> cheers
>
> andrew
>
>

Re: [HACKERS] strip nulls functions for json and jsonb

[Thom Brown]

On 26 October 2014 20:07, Andrew Dunstan  wrote:

>
> On 10/26/2014 03:50 PM, Pavel Stehule wrote:
>
>> Hi
>>
>> I have a question,
>>
>> what is expected result of null strip of
>>
>> {"a": {"b": null, "c", null"} }
>>
>> ?
>>
>>
>
> Please remember not to top-post.
>
> The above is not legal json, so the answer would be an error.
>

I believe Pavel means:

{"a": {"b": null, "c": null} }

-- 
Thom

Re: [HACKERS] strip nulls functions for json and jsonb

[Andrew Dunstan]

On 10/26/2014 03:50 PM, Pavel Stehule wrote:

Hi

I have a question,

what is expected result of null strip of

{"a": {"b": null, "c", null"} }

?




Please remember not to top-post.

The above is not legal json, so the answer would be an error.

cheers

andrew


--
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To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

Re: [HACKERS] strip nulls functions for json and jsonb

[Pavel Stehule]

Hi

I have a question,

what is expected result of null strip of

{"a": {"b": null, "c", null"} }

?

2014-10-26 19:59 GMT+01:00 Andrew Dunstan :

>
> On 10/16/2014 04:12 PM, Pavel Stehule wrote:
>
>>
>>
>> 1. missing documentation
>>
>> 2. I miss more comments related to this functions. This code is relative
>> simple, but some more explanation can be welcome.
>>
>> 3. why these functions are marked as "stable"?
>>
>>
>>
> New patch:
>
> Docs added, functions marked immutable, more comments added.
>
> cheers
>
> andrew
>

Re: [HACKERS] strip nulls functions for json and jsonb

[Andrew Dunstan]

On 10/16/2014 04:12 PM, Pavel Stehule wrote:



1. missing documentation

2. I miss more comments related to this functions. This code is 
relative simple, but some more explanation can be welcome.


3. why these functions are marked as "stable"?




New patch:

Docs added, functions marked immutable, more comments added.

cheers

andrew
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 7e5bcd9..352b408 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10716,6 +10716,19 @@ table2-mapping
 

   
+  
+   json_strip_nulls(from_json json)
+ jsonb_strip_nulls(from_json jsonb)
+   
+   jsonjsonb
+   
+ Returns from_json
+ with all object fields that have null values omitted. Other null values
+ are untouched.
+   
+   json_strip_nulls('[{"f1":1,"f2":null},2,null,3]')
+   [{"f1":1},2,null,3]
+   
  
 

@@ -10752,6 +10765,16 @@ table2-mapping
 
   
 
+  
+
+  If the argument to json_strip_nulls contains duplicate
+  field names in any object, the result could be semantically somewhat
+  different, depending on the order in which they occur. This is not an
+  issue for jsonb_strip_nulls since jsonb values never have
+  duplicate object field names.
+
+  
+
   
 See also  for the aggregate
 function json_agg which aggregates record
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 2d00dbe..06db3e4 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -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)
+{
+	Stripnull

Re: [HACKERS] strip nulls functions for json and jsonb

[Pavel Stehule]

Hello

I checked this patch.

1. There is a consensus we want this feature.

2. This patch implement just this mentioned feature. There is no objection
against design.

3. It is possible to apply this patch and compile without warnings.

4. I tested null stripping on large json, jsonb values without problems.

5. regress tests are enough

6. code is well formatted


Objections & questions:

1. missing documentation

2. I miss more comments related to this functions. This code is relative
simple, but some more explanation can be welcome.

3. why these functions are marked as "stable"?

Regards

Pavel



2014-10-04 1:23 GMT+02:00 Andrew Dunstan :

> As discussed recently, here is an undocumented patch for json_strip_nulls
> and jsonb_strip_nulls.
>
> cheers
>
> andrew
>
>
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>

Re: [HACKERS] strip nulls functions for json and jsonb

[Pavel Stehule]

Hi

2014-10-04 1:23 GMT+02:00 Andrew Dunstan :

> As discussed recently, here is an undocumented patch for json_strip_nulls
> and jsonb_strip_nulls.
>

It is looking well

Regards

Pavel


>
> cheers
>
> andrew
>
>
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> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
> To make changes to your subscription:
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>
>

[HACKERS] strip nulls functions for json and jsonb

[Andrew Dunstan]

As discussed recently, here is an undocumented patch for 
json_strip_nulls and jsonb_strip_nulls.


cheers

andrew
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 2d00dbe..e9636d8 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -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 +3012,169 @@ findJsonbValueFromContainerLen(JsonbContainer *container, uint32 flags,
 
 	return findJsonbValueFromContainer(container, flags, &k);
 }
+
+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)
+	{
+		_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)
+	{
+		_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;
+	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;
+		}
+
+