如何在postgres db中包含JSON数组的列内查询

Question

I have a table in postgres db. In that table I have a column containing JSON array

{
            "DeviceId": "12355",
            "Message": {
                        "Test1": [{"Name": "1"}, {"Result": "Pass"}],
                        "Test2":[{"Name": "2"}, {"Result": "Fail"}],
                        "Test3": [{"Name": "3"}, {"Result": "Pass"}],
                        
            }
}

I need to query inside this and I want my output to be in below format.

DeviceID     Name   Result  
  "12355"    "1"   "Pass"     
  "12355"    "2"   "Fail" 
  "12355"    "3"   "Pass" 

Following is the query which I tried

select DeviceId, Message  -> 'Name' as name, Message  -> 'Result' as Result from table

The result was not as expected

I'm new to postgres DB can anyone help me in this. Thanks in advance

Answer 1

demo:db<>fiddle

SELECT
    mydata ->> 'DeviceId' as device_id,
    tests.value -> 0 ->> 'Name' as name,
    tests.value -> 1 ->> 'Result' as result
FROM mytable,
    json_each(mydata -> 'Message') as tests

You can extract all data from Message into one row per element using json_each() . Afterwards you can access the array elements.

However, your structure seems not very well designed. Instead of

"Test1" : [{"Name": "1"}, {"Result": "Pass"}]

you should think of

"Test1" : {"Name": "1", "Result": "Pass"}