MaxCompute:TO_JSON

Syntax

string to_json(<expr>)

Parameters

Return value

A JSON string is returned.

Examples

• Example 1: Convert an expression of a given complex data type into a JSON string. Sample statements:

  -- The return value is {"a":1,"b":2}. 
  select to_json(named_struct('a', 1, 'b', 2));
  -- The return value is {"time":"26/08/2015"}. 
  select to_json(named_struct('time', "26/08/2015"));
  -- The return value is [{"a":1,"b":2}]. 
  select to_json(array(named_struct('a', 1, 'b', 2)));
  -- The return value is {"a":{"b":1}}. 
  select to_json(map('a', named_struct('b', 1)));
  -- The return value is {"a":1}. 
  select to_json(map('a', 1));
  -- The return value is [{"a":1}]. 
  select to_json(array((map('a', 1))));

• Example 2: The input expression is of the STRUCT type. Sample statements:

  -- The return value is {"a":"B"}. If the expression of the STRUCT type is converted into a JSON string, all keys are converted into lowercase letters. 
  select to_json(named_struct("A", "B"));
  -- The return value is {"k2":"v2"}. The key-value pair to which null belongs is not included in the JSON string that is returned. 
  select to_json(named_struct("k1", cast(null as string), "k2", "v2"));

Related functions

TO_JSON is a complex type function or a string function.

• For more information about the functions that are used to process data of complex data types, such as ARRAY, MAP, STRUCT, and JSON, see Complex type functions.

• For more information about functions related to string searches and conversion, see String functions.