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Remove "invalid concatenation of jsonb objects" error case.

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The jsonb || jsonb operator arbitrarily rejected certain combinations
of scalar and non-scalar inputs, while being willing to concatenate
other combinations.  This was of course quite undocumented.  Rather
than trying to document it, let's just remove the restriction,
creating a uniform rule that unless we are handling an object-to-object
concatenation, non-array inputs are converted to one-element arrays,
resulting in an array-to-array concatenation.  (This does not change
the behavior for any case that didn't throw an error before.)

Per complaint from Joel Jacobson.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/163099.1608312033@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2020-12-21 13:11:29 -05:00
parent b6efd8a6da
commit 75c8ef5ae5
4 changed files with 85 additions and 50 deletions
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11
doc/src/sgml/func.sgml
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@ -11455,10 +11455,13 @@ table2-mapping
<note>
<para>
The <literal>||</literal> operator concatenates the elements at the top level of
each of its operands. It does not operate recursively. For example, if
both operands are objects with a common key field name, the value of the
field in the result will just be the value from the right hand operand.
The <literal>||</literal> operator concatenates two JSON objects by
generating an object containing the union of their keys, taking the
second object's value when there are duplicate keys. All other cases
produce a JSON array: first, any non-array input is converted into a
single-element array, and then the two arrays are concatenated.
It does not operate recursively; only the top-level array or object
structure is merged.
</para>
</note>

83
src/backend/utils/adt/jsonfuncs.c
View File

@ -4583,36 +4583,39 @@ IteratorConcat(JsonbIterator **it1, JsonbIterator **it2,
rk1,
rk2;
r1 = rk1 = JsonbIteratorNext(it1, &v1, false);
r2 = rk2 = JsonbIteratorNext(it2, &v2, false);
rk1 = JsonbIteratorNext(it1, &v1, false);
rk2 = JsonbIteratorNext(it2, &v2, false);
/*
* Both elements are objects.
* JsonbIteratorNext reports raw scalars as if they were single-element
* arrays; hence we only need consider "object" and "array" cases here.
*/
if (rk1 == WJB_BEGIN_OBJECT && rk2 == WJB_BEGIN_OBJECT)
{
/*
* Append the all tokens from v1 to res, except last WJB_END_OBJECT
* Both inputs are objects.
*
* Append all the tokens from v1 to res, except last WJB_END_OBJECT
* (because res will not be finished yet).
*/
pushJsonbValue(state, r1, NULL);
pushJsonbValue(state, rk1, NULL);
while ((r1 = JsonbIteratorNext(it1, &v1, true)) != WJB_END_OBJECT)
pushJsonbValue(state, r1, &v1);
/*
* Append the all tokens from v2 to res, include last WJB_END_OBJECT
* (the concatenation will be completed).
* Append all the tokens from v2 to res, including last WJB_END_OBJECT
* (the concatenation will be completed). Any duplicate keys will
* automatically override the value from the first object.
*/
while ((r2 = JsonbIteratorNext(it2, &v2, true)) != WJB_DONE)
res = pushJsonbValue(state, r2, r2 != WJB_END_OBJECT ? &v2 : NULL);
}
/*
* Both elements are arrays (either can be scalar).
*/
else if (rk1 == WJB_BEGIN_ARRAY && rk2 == WJB_BEGIN_ARRAY)
{
pushJsonbValue(state, r1, NULL);
/*
* Both inputs are arrays.
*/
pushJsonbValue(state, rk1, NULL);
while ((r1 = JsonbIteratorNext(it1, &v1, true)) != WJB_END_ARRAY)
{
@ -4628,48 +4631,40 @@ IteratorConcat(JsonbIterator **it1, JsonbIterator **it2,
res = pushJsonbValue(state, WJB_END_ARRAY, NULL /* signal to sort */ );
}
/* have we got array || object or object || array? */
else if (((rk1 == WJB_BEGIN_ARRAY && !(*it1)->isScalar) && rk2 == WJB_BEGIN_OBJECT) ||
(rk1 == WJB_BEGIN_OBJECT && (rk2 == WJB_BEGIN_ARRAY && !(*it2)->isScalar)))
else if (rk1 == WJB_BEGIN_OBJECT)
{
JsonbIterator **it_array = rk1 == WJB_BEGIN_ARRAY ? it1 : it2;
JsonbIterator **it_object = rk1 == WJB_BEGIN_OBJECT ? it1 : it2;
bool prepend = (rk1 == WJB_BEGIN_OBJECT);
/*
* We have object || array.
*/
Assert(rk2 == WJB_BEGIN_ARRAY);
pushJsonbValue(state, WJB_BEGIN_ARRAY, NULL);
if (prepend)
{
pushJsonbValue(state, WJB_BEGIN_OBJECT, NULL);
while ((r1 = JsonbIteratorNext(it_object, &v1, true)) != WJB_DONE)
pushJsonbValue(state, r1, r1 != WJB_END_OBJECT ? &v1 : NULL);
pushJsonbValue(state, WJB_BEGIN_OBJECT, NULL);
while ((r1 = JsonbIteratorNext(it1, &v1, true)) != WJB_DONE)
pushJsonbValue(state, r1, r1 != WJB_END_OBJECT ? &v1 : NULL);
while ((r2 = JsonbIteratorNext(it_array, &v2, true)) != WJB_DONE)
res = pushJsonbValue(state, r2, r2 != WJB_END_ARRAY ? &v2 : NULL);
}
else
{
while ((r1 = JsonbIteratorNext(it_array, &v1, true)) != WJB_END_ARRAY)
pushJsonbValue(state, r1, &v1);
pushJsonbValue(state, WJB_BEGIN_OBJECT, NULL);
while ((r2 = JsonbIteratorNext(it_object, &v2, true)) != WJB_DONE)
pushJsonbValue(state, r2, r2 != WJB_END_OBJECT ? &v2 : NULL);
res = pushJsonbValue(state, WJB_END_ARRAY, NULL);
}
while ((r2 = JsonbIteratorNext(it2, &v2, true)) != WJB_DONE)
res = pushJsonbValue(state, r2, r2 != WJB_END_ARRAY ? &v2 : NULL);
}
else
{
/*
* This must be scalar || object or object || scalar, as that's all
* that's left. Both of these make no sense, so error out.
* We have array || object.
*/
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid concatenation of jsonb objects")));
Assert(rk1 == WJB_BEGIN_ARRAY);
Assert(rk2 == WJB_BEGIN_OBJECT);
pushJsonbValue(state, WJB_BEGIN_ARRAY, NULL);
while ((r1 = JsonbIteratorNext(it1, &v1, true)) != WJB_END_ARRAY)
pushJsonbValue(state, r1, &v1);
pushJsonbValue(state, WJB_BEGIN_OBJECT, NULL);
while ((r2 = JsonbIteratorNext(it2, &v2, true)) != WJB_DONE)
pushJsonbValue(state, r2, r2 != WJB_END_OBJECT ? &v2 : NULL);
res = pushJsonbValue(state, WJB_END_ARRAY, NULL);
}
return res;

36
src/test/regress/expected/jsonb.out
View File

@ -3654,9 +3654,41 @@ select '{"a":"b"}'::jsonb || '[]'::jsonb;
(1 row)
select '"a"'::jsonb || '{"a":1}';
ERROR: invalid concatenation of jsonb objects
?column?
-----------------
["a", {"a": 1}]
(1 row)
select '{"a":1}' || '"a"'::jsonb;
ERROR: invalid concatenation of jsonb objects
?column?
-----------------
[{"a": 1}, "a"]
(1 row)
select '[3]'::jsonb || '{}'::jsonb;
?column?
----------
[3, {}]
(1 row)
select '3'::jsonb || '[]'::jsonb;
?column?
----------
[3]
(1 row)
select '3'::jsonb || '4'::jsonb;
?column?
----------
[3, 4]
(1 row)
select '3'::jsonb || '{}'::jsonb;
?column?
----------
[3, {}]
(1 row)
select '["a", "b"]'::jsonb || '{"c":1}';
?column?
----------------------

5
src/test/regress/sql/jsonb.sql
View File

@ -973,6 +973,11 @@ select '{"a":"b"}'::jsonb || '[]'::jsonb;
select '"a"'::jsonb || '{"a":1}';
select '{"a":1}' || '"a"'::jsonb;
select '[3]'::jsonb || '{}'::jsonb;
select '3'::jsonb || '[]'::jsonb;
select '3'::jsonb || '4'::jsonb;
select '3'::jsonb || '{}'::jsonb;
select '["a", "b"]'::jsonb || '{"c":1}';
select '{"c": 1}'::jsonb || '["a", "b"]';