红移UDF - 返回JSON键

Question

我想写一个红移UDF与Python返回一个JSON对象的键：测试它只能在对象返回的最后一个键的功能时

create or replace function json_keys (j varchar(max)) 
    returns varchar(max) 
    stable as $$ 
     import json 
     arr = json.loads(j) 
     for key in arr.keys(): 
     return str(key) 
    $$ language plpythonu; 

然而键即

select json_keys('{"key1": "value1", "key2": "value2","key3": "value3"}') -- returns key3 only 

我需要改变什么才能让它返回key1，key2和key3？

Answer 1

Loop返回最后一项。结帐这个。

create or replace function json_keys (j varchar(max)) 
returns varchar(max) 
stable as $$ 
    import json 
    arr = json.loads(j) 
    return '' if not arr else ','.join(arr.keys()) 
$$ language plpythonu; 

select json_keys('{"key1": "value1", "key2": "value2","key3": "value3"}')