star() macro now includes as alias by default, breaking expected behavior

[foundinblank]

Describe the bug

In previous versions, the star() macro produced a comma-separated list of fields, such as

id,
date,
field

With #436 as part of 0.8.0 it now will produce a comma-separated list of fields and aliases, such that the output is

id as id,
date as date,
field as field

Steps to reproduce, expected results, actual results

We have a specific usage of a star() macro where

{% set upstream_model = 'model1' %}
{% set partition_columns = star(from=ref(model1)) %}

select
    *,
    first_value(category) over (partition by {{ partition_columns }}
        order by start_date desc) as past_category
from {{ ref(model1) }} 

Under dbt-utils 0.7.5 this is the generated output:

select
    *,
    first_value(category) over (partition by 
"FIELD1", 
"FIELD2", 
"FIELD3"
        order by start_date desc) as past_category
from staging.model1

Under dbt-utils 0.8.0 this is the generated output, which fails because we can't alias fields within an over() clause

select
    *,
    first_value(category) over (partition by 
"FIELD1" as "FIELD1", 
"FIELD2" as "FIELD2", 
"FIELD3" as "FIELD3"
        order by start_date desc) as past_category
from staging.model1

System information

The contents of your packages.yml file:

Which database are you using dbt with?

• postgres
• redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

installed version: 1.0.0
   latest version: 1.0.0

Up to date!

Plugins:
  - snowflake: 1.0.0

Are you interested in contributing the fix?

I would be, I think what it needs is flags to see if prefix and suffix exist and if neither exist, don't append the as clause. This is the specific line:

dbt-utils/macros/sql/star.sql

Line 27 in eb1ec81

{%- if relation_alias %}{{ relation_alias }}.{% else %}{%- endif -%}{{ adapter.quote(col)|trim }} as {{ adapter.quote(prefix ~ col ~ suffix)|trim }}

So in psuedocode it'd be something like:

{%- if relation_alias %}
{{ relation_alias }}.{% else %}{%- endif -%}{{ adapter.quote(col)|trim }} 

--if prefix is not null or suffix is not null 
as {{ adapter.quote(prefix ~ col ~ suffix)|trim }} 

{%- if not loop.last %},{{ '\n  ' }}{% endif %}

[joellabes]

Yes good call @foundinblank! Even if it wasn't breaking the partition, it's ugly to alias something to itself 😅 I should have thought about this in code review.

If/when you do have a crack at this, could I prevail upon you to add an integration test to the star macro that incorporates a window function or something similar, so that we can catch this sort of thing automatically in the future?

[joellabes]

Just found #468 which looks like it solves this!

[foundinblank]

🙌 great!!