How to debug DBIx::Class?

Question

I was recently working on a Perl project that required me to use DBIx::Class as the ORM to interact with a database. One of the things I found most annoying and just time consuming was just trying to debug and understand what was happening.

I was especially frustrated with and error I was getting Column 'XXXXXX' in where clause is ambiguous and I figured out what was causing this error. It was down to the fact I was requesting columns from 2 different tables which where joined on the XXXXXX attribute and in the WHERE clause the column wasn't being aliased. This lead to DBIx::Class not knowing which column to use.

The most frustrating thing was not knowing what DBIx::Class was doing, leading me to have many doubts about where the error was coming from.

How to efficiently debug this kind of DBIx::Class errors?

Answer 1

So I knew what the error was, but I didn't know exactly where it was being caused. If this was plain old SQL I would've simply added the aliases myself but I didn't know how to do that in DBIx::Class. Moreover, I had no clue what SQL query was actually being executed, which made things even worse.

That's when I found out about the as_query method (https://metacpan.org/pod/DBIx::Class::ResultSet#as_query) which, when logged, prints out the SQL query that DBIx::Class executes. LIFE CHANGER. Saved me from so much trouble and gave me exactly what I needed. Shortly after I was able to solve the issue.

Moral of the story: if you're having trouble seeing what DBIx::Class is doing, use this and save yourself from countless headaches.

Answer 2

You enable debugging by setting the DBIC_TRACE environment variable to 1 or a filename.

That's documented at the very top of DBIx::Class::Manual::Troubleshooting