How to project json key value pair to columns without explicitly specifying name

Question

In customDimensions I have x number of key-value pair data (currently only two Name and Channel as an example in the screenshot below)

and I would like to project them to columns without explicitly specify the name of the key, so that in the future, if a new key-value pair added to the log, I don't have to go back and modify my query in order to display it as a new column.

Thank you!

Answer 1

The Kusto query language includes the bag_unpack() plugin: https://learn.microsoft.com/en-us/azure/kusto/query/bag-unpackplugin

Here's an example:

datatable(anotherColumn:int, customDimensions:dynamic)
[
    1, dynamic({"Name":"mfdg",  "Channel":"wer"}),
    2, dynamic({"Name":"mfdg2", "Channel":"wer2"}),
    3, dynamic({"NotAName":2.22, "NotAChannel":7}),
]
| evaluate bag_unpack(customDimensions)

Which yields:

| anotherColumn | Name  | Channel | NotAName | NotAChannel |
|---------------|-------|---------|----------|-------------|
| 1             | mfdg  | wer     |          |             |
| 2             | mfdg2 | wer2    |          |             |
| 3             |       |         | 2.22     | 7           |