Fbc and fbp as event parameters - minor issue

Thanks for providing the CAPI tag for sGTM. I’ve used it for several customers, and it’s a pleasure to work with.

For $BORING_REASONS, I need to send the fbc and fbp as event parameters from GTM to sGTM. I checked the template, and the template handles that case:

if (!fbc) fbc = eventData._fbc;
if (!fbp) fbp = eventData._fbp;

Unfortunately, event parameters cannot begin with underscores (_). See here

If you set a parameter in GTM to start with an _, it doesn’t get sent to sGTM.

I got around the problem by sending the values in another parameter and doing a transform to add the _fbc, _fpb to the eventData in sGTM.

Thought you’d like the heads up.

You can send these parameters to event data with any name and just overwrite them in the FB tag, user data section:

Often use not GA4 but another transport mechanism like Data tag -and then there is no such problem with variable names.

I didn’t think of using the tag option - appreciate your response.