Important

The SingleStore 9.1 release candidate (RC) is available now. It will be promoted to general availability (GA) soon and at that time it will be renamed to SingleStore 10.

In the interim, SingleStore 9.1 RC can be used to preview, evaluate, and provide feedback on the new and upcoming features in SingleStore 10, while SingleStore 9.0 is recommended for production workloads.

BSON_EXTRACT_BSON

Syntax

BSON_EXTRACT_BSON(<bson_input> [, path_key_1, path_key_2, ..., path_key_n])

Arguments

<bson_input>: A valid BSON object or an expression that evaluates to a valid BSON object.
<path_key>: (Optional) A comma-separated list of dictionary keys or array positions (zero-based index) that represent the path to the BSON object or the value to extract.

Return Type

A BSON value.

Remarks

If the <path_key> argument is not specified, the top-level document or value is returned.
If the input is a top-level BSON value, BSON_EXTRACT_BSON() returns the input value if the <path_key> argument is not specified. Otherwise, it returns NULL.
If the specified <path_key> does not exist, returns NULL.

Examples

Note: The following examples explicitly cast string to BSON for clarity. Similarly, the output is cast to JSON.

The examples use the following data set:

SQL

CREATE DATABASE dbTest;
USE dbTest;

CREATE TABLE bsonExample(a BSON);
INSERT INTO bsonExample VALUES('{"doc":{"field1":42,"field2":true,"field3":"foobar","field4":[1,2,3],"child_doc":{"a":123}}}':>BSON);
INSERT INTO bsonExample VALUES('{"doc":{"field1":28,"field2":false,"field3":"barfoo","field4":[7,8,9],"child_doc":{"a":42}}}':>BSON);
INSERT INTO bsonExample VALUES('{"doc":{"field1":32,"field2":true,"field3":"hohoho","field4":[3,2,1],"child_doc":{"a":488}}}':>BSON);

The following example returns the top level document because the <path_key> is not specified:

SQL

SELECT BSON_EXTRACT_BSON(a):>JSON AS Result FROM bsonExample;

+----------------------------------------------------------------------------------------------+
| Result                                                                                       |
+----------------------------------------------------------------------------------------------+
| {"doc":{"child_doc":{"a":123},"field1":42,"field2":true,"field3":"foobar","field4":[1,2,3]}} |
| {"doc":{"child_doc":{"a":42},"field1":28,"field2":false,"field3":"barfoo","field4":[7,8,9]}} |
| {"doc":{"child_doc":{"a":488},"field1":32,"field2":true,"field3":"hohoho","field4":[3,2,1]}} |
+----------------------------------------------------------------------------------------------+

The following example returns the BSON document at the specified path:

SQL

SELECT BSON_EXTRACT_BSON(a, 'doc','child_doc'):>JSON AS Result FROM bsonExample;

+-----------+
| Result    |
+-----------+
| {"a":42}  |
| {"a":488} |
| {"a":123} |
+-----------+

The following example returns the BSON array at the specified path:

SQL

SELECT BSON_EXTRACT_BSON(a, 'doc', 'field4'):>JSON AS Result FROM bsonExample;

+---------+
| Result  |
+---------+
| [3,2,1] |
| [7,8,9] |
| [1,2,3] |
+---------+

The following example returns NULL because the specified <path_key> does not exist.

SQL

SELECT BSON_EXTRACT_BSON(a, 'doc', 'doc'):>JSON AS Result FROM bsonExample;

+--------+
| Result |
+--------+
| NULL   |
| NULL   |
| NULL   |
+--------+