retrieving array from json as a table in Kusto - arrays

Question

I am trying to retrieve all the rows from a Json array. The json is similar to the one shown below.
{
"messageId": "123",
"fileName": "abc.json",
"payload": {
"routeStatus": "FINAL",
"activities": [
{
"durationSeconds": 1800,
"location": {
"longitude": 151.2603,
"latitude": -33.7644
},
"type": "DEPART",
"slot": {
"start": "2020-04-14T19:05:00.0000000Z",
"cost": null,
"end": "2020-04-15T03:30:00.0000000Z"
}
},
{
"durationSeconds": 1100,
"type": "DRIVE"
},
{
"durationSeconds": 360,
"location": {
"longitude": 151.21814,
"latitude": -33.756319
},
"type": "SERVICE",
"slot": {
"start": "2020-04-14T20:00:00.0000000Z",
"cost": null,
"end": "2020-04-15T00:45:00.0000000Z"
}
},
{
"durationSeconds": 164,
"type": "DRIVE"
}
],
"truck": "XYZ"
}
}
I would like to get all the attributes under the activities in a table as I would need to filter and join to other tables. I am only able to retrieve one row from the array. Any pointers would be helpful.

Answer 1

you can use mv-expand or mv-apply.
for example:
print d = dynamic({
"messageId": "123",
"fileName": "abc.json",
"payload": {
"routeStatus": "FINAL",
"activities": [
{
"durationSeconds": 1800,
"location": {
"longitude": 151.2603,
"latitude": -33.7644
},
"type": "DEPART",
"slot": {
"start": "2020-04-14T19:05:00.0000000Z",
"cost": null,
"end": "2020-04-15T03:30:00.0000000Z"
}
},
{
"durationSeconds": 1100,
"type": "DRIVE"
},
{
"durationSeconds": 360,
"location": {
"longitude": 151.21814,
"latitude": -33.756319
},
"type": "SERVICE",
"slot": {
"start": "2020-04-14T20:00:00.0000000Z",
"cost": null,
"end": "2020-04-15T00:45:00.0000000Z"
}
},
{
"durationSeconds": 164,
"type": "DRIVE"
}
],
"truck": "XYZ"
}
})
| mv-expand d.payload.activities
| project durationSeconds = tolong(d_payload_activities.durationSeconds), type = tostring(d_payload_activities.type)