`object has no attribute` error on join

Suppose I have a many-to-one relationship between products and departments, where both tables have a joinrow_id column. Suppose that we only have one product and its name is "chair". The chair is in the only department, whose name is “all products”, and whose “priority” is null.

I’m seeing inconsistent behavior between these two queries:

builder = Products.select(Products.name,                                                                                                                               
                          Departments.name)\
                  .join(Departments, on=(Departments.joinrow == Products.joinrow).alias('department'))\
                  .switch(Products)\
                  .where(Products.id == 1)

builder = Products.select(Products.name,                                                                                                                               
                          Departments.priority)\
                  .join(Departments, on=(Departments.joinrow == Products.joinrow).alias('department'))\
                  .switch(Products)\
                  .where(Products.id == 1)

In the first case, seemingly because the name field is truthy, I am able to type: [r for r in builder][0].department.name

But in the second case, if I try [r for r in builder][0].department.priority, the library raises an error: Products has no attribute 'department'.

This is easily remedied. I just have to make sure that, in my select, I include a column from departments whose value is always truthy.

I just wanted to bring this behavior to your attention in case you weren’t aware.

[coleifer]

For your example, you should be able to workaround the “NULL” priority by also selecting the Department’s primary key, e.g.

builder = (Products
           .select(Products.name, Departments.id, Departments.priority)
           .join(Departments, on=(Departments.joinrow == Products.joinrow).alias('department'))
           .where(Products.id == 1))

[skatenerd]

I’ve created a self-contained example here:

https://gist.github.com/skatenerd/45b65a361384869e39ee20069d8ea7d4

On my machine, I’m able to make the first print statement in go(), but the second crashes with AttributeError: 'Products' object has no attribute 'department'