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json_typeof function.

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Andrew Tipton.
This commit is contained in:
Andrew Dunstan
2013-10-10 12:21:59 -04:00
parent 4b7b9a7904
commit 4d212bac17
8 changed files with 158 additions and 4 deletions
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31
doc/src/sgml/func.sgml
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@@ -10095,7 +10095,7 @@ table2-mapping
</entry>
<entry><type>json</type></entry>
<entry>
Returns JSON object pointed to by <parameter>path_elems</parameter>.
Returns JSON value pointed to by <parameter>path_elems</parameter>.
</entry>
<entry><literal>json_extract_path('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}','f4')</literal></entry>
<entry><literal>{"f5":99,"f6":"foo"}</literal></entry>
@@ -10109,7 +10109,7 @@ table2-mapping
</entry>
<entry><type>text</type></entry>
<entry>
Returns JSON object pointed to by <parameter>path_elems</parameter>.
Returns JSON value pointed to by <parameter>path_elems</parameter>.
</entry>
<entry><literal>json_extract_path_text('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}','f4', 'f6')</literal></entry>
<entry><literal>foo</literal></entry>
@@ -10192,7 +10192,7 @@ table2-mapping
</entry>
<entry><type>SETOF json</type></entry>
<entry>
Expands a JSON array to a set of JSON elements.
Expands a JSON array to a set of JSON values.
</entry>
<entry><literal>json_array_elements('[1,true, [2,false]]')</literal></entry>
<entry>
@@ -10205,6 +10205,23 @@ table2-mapping
</programlisting>
</entry>
</row>
<row>
<entry>
<indexterm>
<primary>json_typeof</primary>
</indexterm>
<literal>json_typeof(json)</literal>
</entry>
<entry><type>text</type></entry>
<entry>
Returns the type of the outermost JSON value as a text string. The types are
<literal>object</>, <literal>array</>, <literal>string</>, <literal>number</>,
<literal>boolean</>, and <literal>null</>. (See note below regarding the
distinction between a JSON <literal>null</> and a SQL NULL.)
</entry>
<entry><literal>json_typeof('-123.4')</literal></entry>
<entry><literal>number</literal></entry>
</row>
</tbody>
</tgroup>
</table>
@@ -10237,6 +10254,14 @@ table2-mapping
</para>
</note>
<note>
<para>
The <literal>json_typeof</> function's <literal>null</> return value should not be confused
with a SQL NULL. While calling <literal>json_typeof('null'::json)</> will return <literal>null</>,
calling <literal>json_typeof(NULL::json)</> will return a SQL NULL.
</para>
</note>
<para>
See also <xref linkend="functions-aggregate"> about the aggregate
function <function>json_agg</function> which aggregates record