Campaign preview fails when using TrackLink variable with dynamic template variables

[tkempken]

Version:

• listmonk: v2.5.1 (a6a2b69 2023-08-15T15:49:28Z, linux/amd64)
• OS: Docker / Ubuntu

Description of the bug and steps to reproduce:
The campaign preview fails with error below once using dynamic template variables in combination with TrackLink handler. The generated mails are correct and track link is working fine too. Just the preview fails.

Screenshots:

{"message":"Error rendering message: template: content:222:182: executing \"content\" at \u003c.Subscriber.Attribs.app_media_url\u003e: invalid value; expected string"}

Raw HTML Template Code:
<a href="{{ TrackLink .Subscriber.Attribs.app_media_url }}"

There might be a relation with #667 . Based on the reply of @knadh we used the TrackLink handler like the given example.

<a href="{{ TrackLink .Subscriber.Attribs.jobs.link }}">View</a> works in d2cf6e0. This will be available in the upcoming release.

[knadh]

I tried this locally and it works. <a href="{{ TrackLink .Subscriber.Attribs.app_media_url }}">Test</a>. However, it fails when app_media_url isn't present. If you are unable to ensure that this field is present for all subscribers, you could put it in a {{ if .Subscriber.Attribs.app_media_url }} check instead.

[tkempken]

Hi, this works on delivery. But is preview working for you? The preview hasn't the variable set - as usual.

[knadh]

Yes, it works in the preview too. Preview picks up a random subscriber from the mailing list and as long as they have the attribute value set, it works.