Remove "invalid concatenation of jsonb objects" error case.

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

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 415c2bf035330a457323bdcfa4a6539b7bddeb5a..3a25162d8c4090fb6cf05a934076c4490a15ff4b 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10493,10 +10493,13 @@ table2-mapping
 
   <note>
    <para>
-    The <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>
 

diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 9330a61ef4bcb230dfd1dc8e9917ef2ecb6350fb..4c59494ecc7185c25aabefa4de8ab6d8a46e4106 100644 (file)
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -3628,36 +3628,39 @@ 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)) != 0)
+       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)
        {
@@ -3673,48 +3676,40 @@ 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)) != 0)
-               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)) != 0)
-               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)) != 0)
-               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;

diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index ffeca69e286ea29e73a48e5ecd0d7968710f02ff..701cb21b12d178cd2b97fc072b509165a447c939 100644 (file)
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -3054,9 +3054,41 @@ 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?       
 ----------------------

diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index 0d7ce5e4d966bea30356ca96c1a3b72927f8f9a1..f47b0ad13dad08bf6a6fd2e9b1dca44ae7a216f7 100644 (file)
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -772,6 +772,11 @@ 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"]';