How do I parse nested JSON-objects in SQL? - sql

Question

I have a string of JSON, returned by an API, that looks something like this:
{
"data": {
"transactions": {
"edges": [
{
"node": {
"text": "debet",
"invoiceAmount": "1.0000"
}
},
{
"node": {
"text": "kredit",
"invoiceAmount": "-1.0000"
}
}
]
}
}
}
It is valid JSON, however the only way that I am able to parse in sql is by manipulating the string first. Like this:
[
{
"node": {
"text": "debet",
"invoiceAmount": "1.0000"
}
},
{
"node": {
"text": "kredit",
"invoiceAmount": "-1.0000"
}
}
]
E.g. below. How do I achieve this without manipulating the string?
DECLARE #json NVARCHAR(MAX);
SET #json = N'[{"node":{"text":"debet","invoiceAmount":"1.0000"}},{"node":{"text":"kredit","invoiceAmount":"-1.0000"}}]';
SELECT *
FROM OPENJSON(#json)
WITH (
text NVARCHAR(50) '$.node.text',
invoiceAmount MONEY '$.node.surname'
)
I tried $.data.transactions.edges.node.text. SQL returns NULL

Answer 1

You can use
SELECT *
FROM OPENJSON(JSON_QUERY(#json, '$.data.transactions.edges'))
WITH (
text VARCHAR(100) '$.node.text',
invoiceAmount DECIMAL(10,4) '$.node.invoiceAmount'
)
to get the desired values out of your original string.
(DB Fiddle)
The JSON_QUERY first extracts the array and then that is expanded out with OPENJSON.