Per-request custom properties on auto-collected request

I can’t seem to find any docs or examples about how to add custom properties onto auto-collected requests. For example, a userId or any other data that is discovered or calculated during the processing of a request.

I’ve tried stashing the data into

appInsights.defaultClient.context.tags[myKey] = 'foo';

but the additional properties don’t show up in customDimensions (or anywhere if I try | search ‘foo’).

Am I missing a mechanism that allows custom properties to be added to auto-collected requests?

[OsvaldoRosado]

What you tried is actually quite close!

What you’ll want instead is appInsights.defaultClient.commonProperties[myKey] = 'foo';

client.context.tags is only for well-known Application Insights fields (like user id via the property nameai.user.id) rather than custom properties. You can reference the list of accepted tag names through the ContextTagKeys class (https://github.com/Microsoft/ApplicationInsights-node.js/blob/7b145dcfdbe7afac146e8ef27898395505dcb2df/Declarations/Contracts/Generated/ContextTagKeys.ts )

Alternatively, the generic approach for modifying telemetry items (autocollected or otherwise) is a telemetry processor. They’re described in the readme but here’s an example:

appInsights.defaultClient.addTelemetryProcessor(( envelope, context ) => {
    var data = envelope.data.baseData;
    data.properties['mykey'] = 'myvalue';
    return true;
});

If you’re using automatic dependency correlation, you can stash your own data for retrieval via the context variable by setting fields on the object returned by appInsights.getCorrelationContext(). The readme has more in-depth info about that (and what data is returned in the context variable by default)

The telemetry processor + context approach will be the most reliable if you handle requests in parallel (and the values are determined based on the request), as you otherwise won’t be able to ensure that the value you set in commonProperties will be the right one for the request being recorded at the time of telemetry recording.

[goto1]

Would you accept a PR that shows an example that uses a custom property on the getCorrelationContext() object and uses a custom telemetry processor to track per-request data?

Similar to something like the following:

• Adding authenticated user ID information in server-side NodeJS Application Insights events

I had to dig through a bunch of issues before I was able to figure out what to do, so an example would be nice to have in the docs.