How to parse json array in kusto query language

Question

How to parse json array in kusto query language. I have an output column which is having value in JSON array format as shown below. I Need to parse it to get values in form of two columns.

{"count": 14
"value": [
        {
            "Total_Record_Count": 16608,
            "date": "2021-03-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 27254,
            "date": "2021-02-24T00:00:00Z"
        },
        {
            "Total_Record_Count": 6,
            "date": "2021-02-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 26964,
            "date": "2021-01-15T00:00:00Z"
        },
        {
            "Total_Record_Count": 134516,
            "date": "2020-12-18T00:00:00Z"
        },
        {
            "Total_Record_Count": 27345,
            "date": "2020-12-16T00:00:00Z"
        },
        {
            "Total_Record_Count": 521,
            "date": "2020-12-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 4,
            "date": "2020-11-02T00:00:00Z"
        },
        {
            "Total_Record_Count": 6,
            "date": "2020-10-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 1,
            "date": "2020-09-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 3,
            "date": "2020-08-03T00:00:00Z"
        },
        {
            "Total_Record_Count": 18,
            "date": "2020-07-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 18754,
            "date": "2020-06-16T00:00:00Z"
        },
        {
            "Total_Record_Count": 4451898,
            "date": "2020-06-08T00:00:00Z"
        }
    ]}

How can I achieve it using output column name instead of using full json array.

Answer 1

Please see example below that uses mv-expand operator for breaking array into rows. https://learn.microsoft.com/en-us/azure/data-explorer/kusto/query/mvexpandoperator

print d = dynamic(
{"count": 14,
"value": [
        {
            "Total_Record_Count": 16608,
            "date": "2021-03-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 27254,
            "date": "2021-02-24T00:00:00Z"
        },
        {
            "Total_Record_Count": 6,
            "date": "2021-02-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 26964,
            "date": "2021-01-15T00:00:00Z"
        },
        {
            "Total_Record_Count": 134516,
            "date": "2020-12-18T00:00:00Z"
        },
        {
            "Total_Record_Count": 27345,
            "date": "2020-12-16T00:00:00Z"
        },
        {
            "Total_Record_Count": 521,
            "date": "2020-12-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 4,
            "date": "2020-11-02T00:00:00Z"
        },
        {
            "Total_Record_Count": 6,
            "date": "2020-10-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 1,
            "date": "2020-09-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 3,
            "date": "2020-08-03T00:00:00Z"
        },
        {
            "Total_Record_Count": 18,
            "date": "2020-07-01T00:00:00Z"
        },
        {
            "Total_Record_Count": 18754,
            "date": "2020-06-16T00:00:00Z"
        },
        {
            "Total_Record_Count": 4451898,
            "date": "2020-06-08T00:00:00Z"
        }
    ]})
| project Value = d.['value'] 
| mv-expand Value
| project Count = tolong(Value.['Total_Record_Count']), Date = todatetime(Value.['date'])

Count	Date
4451898	2020-06-08 00:00:00.0000000
18754	2020-06-16 00:00:00.0000000
18	2020-07-01 00:00:00.0000000
3	2020-08-03 00:00:00.0000000
1	2020-09-01 00:00:00.0000000
6	2020-10-01 00:00:00.0000000
4	2020-11-02 00:00:00.0000000
521	2020-12-01 00:00:00.0000000
27345	2020-12-16 00:00:00.0000000
134516	2020-12-18 00:00:00.0000000
26964	2021-01-15 00:00:00.0000000
6	2021-02-01 00:00:00.0000000
27254	2021-02-24 00:00:00.0000000
16608	2021-03-01 00:00:00.0000000