JSON functions and operators

JSON functions

jsonb_array_elements

Expands the top-level JSON array into a set of JSON values.

Syntax

jsonb_array_elements ( jsonb ) → setof jsonb

Example

SELECT * FROM jsonb_array_elements('[1,true, [2,false]]'::jsonb);
------RESULT
1
true
[2, false]

jsonb_array_elements_text

Expands the top-level JSON array into a set of text (varchar) values.

Syntax

jsonb_array_elements_text ( jsonb ) → setof varchar

Example

SELECT * FROM jsonb_array_elements_text('["foo", "bar"]'::jsonb)
------RESULT
foo
bar

jsonb_array_length

Returns the number of elements in the top-level JSON array.

Syntax

jsonb_array_length ( jsonb ) → integer

Example

SELECT jsonb_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
------RESULT
5

jsonb_each

Expands the top-level JSON object into a set of key-value pairs.

Syntax

jsonb_each ( jsonb ) → setof record ( key varchar, value jsonb )

Example

SELECT * FROM jsonb_each('{"a":"foo", "b":"bar"}'::jsonb);
------RESULT
a "foo"
b "bar"

jsonb_each_text

Expands the top-level JSON object into a set of key-value pairs. The returned values will be of type varchar.

Syntax

jsonb_each_text ( jsonb ) → setof record ( key varchar, value varchar )

Example

SELECT * FROM jsonb_each_text('{"a":"foo", "b":"bar"}'::jsonb);
------RESULT
 key | value 
-----+-------
 a   | foo
 b   | bar

jsonb_extract_path

Extracts JSON sub-object at the specified path.

This function is equivalent to the #> operator in functionality.

Syntax

jsonb_extract_path ( from_json jsonb, VARIADIC path_elems text[] ) → jsonb

• from_json is the input JSON value from which to extract the sub-object.

• path_elems is the path elements that specify the location of the desired sub-object in the JSON structure. Multiple path elements can be provided as separate arguments.

Example

SELECT json_extract_path('{"f2":{"f3":1},"f4":{"f5":99,"f6":"foo"}}', 'f4', 'f6')
------RESULT
"foo"

jsonb_extract_path_text

Extracts JSON sub-object at the specified path as text.

This function is equivalent to the #>> operator in functionality.

Syntax

jsonb_extract_path_text ( from_json jsonb, VARIADIC path_elems text[] ) → text

Example

SELECT jsonb_extract_path_text('{"f2":{"f3":1},"f4":{"f5":99,"f6":"string"}}', 'f4', 'f6');
------RESULT
string

jsonb_object_keys

Returns the set of keys in the top-level JSON object.

Syntax

jsonb_object_keys ( jsonb ) → setof varchar

Example

SELECT * FROM jsonb_object_keys('{"f1":"abc","f2":{"f3":"a", "f4":"b"}}'::jsonb);
------RESULT
f1
f2

jsonb_strip_nulls

Removes all object fields that have null values from a given JSONB value, recursively. Empty objects or null values that are not object fields are left untouched.

Syntax

jsonb_strip_nulls ( jsonb ) → jsonb

Example

-- Handling non-null values
SELECT jsonb_strip_nulls('{"a": 1, "b": null, "c": {"d": null, "e": 2}}');
------RESULT
{"a": 1, "c": {"e": 2}}

-- Empty object preservation
SELECT jsonb_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }');
------RESULT
{"a": {}, "d": {}}

jsonb_typeof

Returns the type of the top-level JSON value as a text string.

Syntax

jsonb_typeof ( jsonb ) → varchar

Example

SELECT jsonb_typeof ('-123.4');
------RESULT
number

jsonb_pretty

This function takes a jsonb value and returns a text representing the formatted, indented JSON value.

Syntax

jsonb_pretty ( jsonb JSONB ) → TEXT

Examples

SELECT jsonb_pretty('[{"f1":1,"f2":null}, 2]');
------RESULT
[
    {
        "f1": 1,
        "f2": null
    },
    2
]

jsonb_object

This function takes an array of text elements and returns a jsonb object where adjacent pairs of values are taken as the key and value of an object property.

Syntax

jsonb_object ( text_array TEXT[] ) → JSONB

Examples

jsonb_object('{a, 1, b, def, c, 3.5}' :: text[]) → {"a": "1", "b": "def", "c": "3.5"}
jsonb_object(array['a', null]) → {"a": null}

JSON operators

jsonb -> integer → jsonb

Extracts the n'th element of a JSON array (array elements are indexed from zero, but negative integers count from the end).

Example

SELECT'[{"a":"foo"},{"b":"bar"},{"c":"baz"}]'::jsonb -> 2;
------RESULT
 {"c":"baz"}

jsonb -> varchar → jsonb

Extracts JSON object field with the given key.

Example

SELECT '{"a": {"b":"foo"}}'::jsonb -> 'a';
------RESULT
 {"b": "foo"}

jsonb ->> integer → varchar

Extracts the n'th element of a JSON array, as text.

Example

SELECT '[1,2,3]'::jsonb ->> 2;
------RESULT
3

jsonb ->> varchar → varchar

Extracts JSON object field with the given key, as text.

Example

SELECT '{"a":1,"b":2}'::jsonb ->> 'b';
------RESULT
2

jsonb - text → jsonb

Deletes a key (and its value) from a JSON object, or matching string value(s) from a JSON array.

Examples

'{"a": "b", "c": "d"}'::jsonb - 'a' → {"c": "d"}
'["a", "b", "c", "b"]'::jsonb - 'b' → ["a", "c"]

jsonb - text[] → jsonb

Deletes all matching keys or array elements from a JSON object.

Example

'{"a": "b", "c": "d"}'::jsonb - '{a,c}'::text[] → {}

jsonb - integer → jsonb

Deletes the array element with the specified index (negative integers counting from the end). Throws an error if JSON object is not an array.

Example

'["a", "b"]'::jsonb - 1 → ["a"]

jsonb #- text[] → jsonb

Deletes the field or array element at the specified path, where path elements can be either field keys or array indexes.

Example

'["a", {"b":1}]'::jsonb #- '{1,b}' → ["a", {}]

(jsonb || jsonb) -> jsonb

Concatenates jsonb data.

Examples

SELECT '["a", "b"]'::jsonb || '["a", "d"]'::jsonb;  
SELECT '{"a": "b"}'::jsonb || '{"c": "d"}'::jsonb;
SELECT '[1, 2]'::jsonb || '3'::jsonb;
SELECT '{"a": "b"}'::jsonb || '42'::jsonb;
------RESULT
["a", "b", "a", "d"]
{"a": "b", "c": "d"}
[1, 2, 3]
[{"a": "b"}, 42]

jsonb @> jsonb -> boolean

This operator checks if the left jsonb value contains the right jsonb value. For a detailed description and examples about containment and existence, see jsonb Containment and Existence in PostgreSQL's documentation.

Examples

'[1, 2, 3]'::jsonb @> '[1, 3]'::jsonb → t

'{"product": "PostgreSQL", "version": 9.4, "jsonb": true}'::jsonb @> '{"version": 9.4}'::jsonb → t

'{"foo": {"bar": "baz"}}'::jsonb @> '{"bar": "baz"}'::jsonb → f

'{"foo": {"bar": "baz"}}'::jsonb @> '{"foo": {}}'::jsonb → t

jsonb <@ jsonb -> boolean

This operator checks if the left jsonb value is contained within the right jsonb value. For a detailed description and examples about containment and existence, see jsonb Containment and Existence in PostgreSQL's documentation.

Examples

'{"b":2}'::jsonb <@ '{"a":1, "b":2}'::jsonb → t

jsonb ? text -> boolean

This operator checks if a string exists as a top-level array element or object key within a jsonb value.

Examples

'["foo", "bar", "baz"]'::jsonb ? 'bar' → t

'{"foo": "bar"}'::jsonb ? 'foo' → t

'{"foo": "bar"}'::jsonb ? 'bar' → f

'{"foo": {"bar": "baz"}}'::jsonb ? 'bar' → f

'"foo"'::jsonb ? 'foo' → t

jsonb ?| text[] -> boolean

This operator checks if any string in an array exists as a top-level array element or object key within a jsonb value.

Examples

'{"a":1, "b":2, "c":3}'::jsonb ?| array['b', 'd'] → t

'["a", "b", "c"]'::jsonb ?| array['b', 'd'] → t

'"b"'::jsonb ?| array['b', 'd'] → t

json ?& text[] -> boolean

This operator checks if all strings in an array exist as top-level array elements or object keys within a jsonb value.

Examples

'{"a":1, "b":2, "c":3}'::jsonb ?& array['a', 'b'] → t

'["a", "b", "c"]'::jsonb ?& array['a', 'b'] → t

'["a", "b", "c"]'::jsonb ?& array['a', 'd'] → f

jsonb #> text[] -> jsonb

This operator extracts a nested value from a JSONB object using a text array of keys or indices.

Examples

'{"a": {"b": ["foo","bar"]}}'::jsonb #> '{a,b,1}'::text[] → "bar"

'{"a": {"b": ["foo","bar"]}}'::jsonb #> '{a,b,null}'::text[] → NULL

jsonb #>> text[] -> text

This operator extracts a nested value as text from a JSONB object using a text array of keys or indices.

Examples

'{"a": {"b": ["foo","bar"]}}'::jsonb #>> '{a,b,1}'::text[] → bar

'{"a": {"b": ["foo",null]}}'::jsonb #>> '{a,b,1}'::text[] → NULL

'{"a": {"b": ["foo","bar"]}}'::jsonb #>> '{a,b,null}'::text[] → NULL

IS JSON predicate

This predicate tests whether an expression can be parsed as JSON, optionally of a specified type. It evaluates the JSON structure and returns a boolean result indicating whether the value matches the specified JSON type.

Syntax

expression IS [ NOT ] JSON [ VALUE | ARRAY | OBJECT | SCALAR ] → bool

If SCALAR, ARRAY, or OBJECT is specified, the test is whether or not the JSON is of that particular type.

Example

SELECT js,
  js IS JSON "json?",
  js IS JSON SCALAR "scalar?",
  js IS JSON OBJECT "object?",
  js IS JSON ARRAY "array?"
FROM (VALUES
      ('123'), ('"abc"'), ('{"a": "b"}'), ('[1,2]'),('abc')) foo(js);

Result

 js         | json? | scalar? | object? | array?
------------+-------+---------+---------+---------
 123        | t     | t       | f       | f
 "abc"      | t     | t       | f       | f
 {"a": "b"} | t     | f       | t       | f
 [1,2]      | t     | f       | f       | t
 abc        | f     | f       | f       | f