add macro to get columns

README.md

@@ -587,21 +587,15 @@ This macro returns the unique values for a column in a given [relation](https://
 ```
 
 #### get_columns ([source](macros/sql/get_columns.sql))
-This macro returns the unique columns for a given [relation](https://docs.getdbt.com/docs/writing-code-in-dbt/class-reference/#relation) as a comma-separated list.
+This macro returns an iterable Jinja list of columns for a given [relation](https://docs.getdbt.com/docs/writing-code-in-dbt/class-reference/#relation)
 
 **Args:**
 - `from` (required): a [Relation](https://docs.getdbt.com/reference/dbt-classes#relation) (a `ref` or `source`) that contains the list of columns you wish to select from
 - `except` (optional, default=`[]`): The name of the columns you wish to exclude
 
-{% set column_names = get_columns(from=ref('fct_rate_rapid_onboarding'), except=["rate_rapid_onboarding__survey_question_response_id", "rate_rapid_onboarding__survey_response_id"]) %}
-
-{% for column_name in column_names %}
-    max({{ column_name }}) ... as '{{ column_name }}'_test,
-{% endfor %}
-
 **Usage:**
 ```sql
--- Returns a list of the columns from a relation, then iterate in a for loop
+-- Returns a list of the columns from a relation, so you can then iterate in a for loop
 {% set column_names = get_columns(from=ref('your_model'), except=["field_1", "field_2"]) %}
 ...
 {% for column_name in column_names %}

macros/sql/get_columns.sql

@@ -1,4 +1,10 @@
 {% macro get_columns(from, except=[]) -%}
+    {{ return(adapter.dispatch('get_columns', 'dbt_utils')(from, except)) }}
+{% endmacro %}
+
+{% macro default__get_columns(from, except=[]) -%}
+    {%- do dbt_utils._is_relation(from, 'get_columns') -%}
+    {%- do dbt_utils._is_ephemeral(from, 'get_columns') -%}
 
     {# -- Prevent querying of db in parsing mode. This works because this macro does not create any new refs. #}
     {%- if not execute -%}

macros/sql/star.sql

@@ -11,18 +11,7 @@
         {{ return('') }}
     {% endif %}
 
-    {%- set include_cols = [] %}
-    {%- set cols = adapter.get_columns_in_relation(from) -%}
-    {%- set except = except | map("lower") | list %}
-    {%- for col in cols -%}
-
-        {%- if col.column|lower not in except -%}
-            {% do include_cols.append(col.column) %}
-
-        {%- endif %}
-    {%- endfor %}
-
-    {%- for col in include_cols %}
+    {%- for col in adapter.get_columns(from, except) %}
 
         {%- if relation_alias %}{{ relation_alias }}.{% else %}{%- endif -%}{{ adapter.quote(col)|trim }} {%- if prefix!='' or suffix!='' -%} as {{ adapter.quote(prefix ~ col ~ suffix)|trim }} {%- endif -%}
         {%- if not loop.last %},{{ '\n  ' }}{% endif %}