Append in nested array JSON object in oracle - json

Question

I have JSON document column in one of the table and its structure is like:-
{
"root":[{"MCR":"MCR_1",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"ABC1",
"MCR_COLUMN_2":"ABC2"
}
},
{"MCR":"MCR_2",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"XYZ1",
"MCR_COLUMN_2":"XYZ2"
}
}
]
}
Now I want to write a merge statement to merge in this document to manage two cases
CASE-1) If MCR value is already present in document, then directly append MCR_COLUMN_x and its value to JSON object of its MCR_COLUMNS. eg. I want to append
{"MCR":"MCR_1",
"MCR_COLUMNS":{
"MCR_COLUMN_3":"ABC3"
}
}
so, the updated document should be
{
"root":[{"MCR":"MCR_1",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"ABC1",
"MCR_COLUMN_2":"ABC2",
"MCR_COLUMN_3":"ABC3"
}
},
{"MCR":"MCR_2",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"XYZ1",
"MCR_COLUMN_2":"XYZ2"
}
}
]
}
CASE-2) If MCR value does not exist then it appends a new JSON object into the root array. for eg: if i want to append
{"MCR":"MCR_3",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"UVW1",
"MCR_COLUMN_2":"UVW2"
}
}
then updated document should be
{
"root":[{"MCR":"MCR_1",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"ABC1",
"MCR_COLUMN_2":"ABC2"
}
},
{"MCR":"MCR_2",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"XYZ1",
"MCR_COLUMN_2":"XYZ2"
}
},
{"MCR":"MCR_3",
"MCR_COLUMNS":{
"MCR_COLUMN_1":"UVW1",
"MCR_COLUMN_2":"UVW2"
}
}
]
}
I had tried JSON_mergepatch and JSON_Transform but case-1 I'm not able to achieve. And since I'll not have before-hand knowledge whether MCR is already present or not, I just can not only right solution for case-2.
Any help or suggestion will be very much appreciated.

Answer 1

To check if the MCR value exists:
WHERE json_exists(json_value, '$?(#.root[*].MCR == "MCR_1")')
To add an item to MCR_COLUMNS
update test_js
set json_value = json_transform(
json_value,
INSERT '$.root.MCR_COLUMNS.MCR_COLUMN_3' = 'ABC3'
)
where json_exists(json_value, '$?(#.root[*].MCR == "MCR_1")')
;
To add an item to root array:
update test_js
set json_value = json_transform(
json_value,
APPEND '$.root' = '{"MCR":"MCR_3", "MCR_COLUMNS":{ "MCR_COLUMN_1":"UVW1", "MCR_COLUMN_2":"UVW2" } }' FORMAT JSON
)
where not json_exists(json_value, '$?(#.root[*].MCR == "MCR_3")')
;

Answer 2

In addition to #p3consulting's answer, to insert into a particular array element only(here in this case 'MCR_1') further conditions can be applied to INSERT.
update test_js
set json_value = json_transform( json_value, INSERT '$.root[*]?(#.MCR=="MCR_1").MCR_COLUMNS.MCR_COLUMN_4' = 'ABC4') )
where json_exists(json_value, '$?(#.root[*].MCR == "MCR_1")') ;