add macro to get columns (#516)

* add macro to get columns

* star macro should use get_columns

* add adapter.

* swap adapter for dbt_utils

Co-authored-by: Joel Labes <joel.labes@dbtlabs.com>

* update documentation

* add output_lower arg

* update name to get_filtered_columns_in_relation from get_columns

* add tests

* forgot args

* too much whitespace removal

    -----------
    Actual:
    -----------
    --->"field_3"as "test_field_3"<---

    -----------
    Expected:
    -----------
    --->"field_3" as "test_field_3"<---

* didnt mean to move a file that i did not create. moving things back.

* remove lowercase logic

* limit_zero

Co-authored-by: Joel Labes <joel.labes@dbtlabs.com>

Author: patkearns10

README.md

@@ -30,6 +30,7 @@ For compatibility details between versions of dbt-core and dbt-utils, [see this
 
 - [Introspective macros](#introspective-macros):
     - [get_column_values](#get_column_values-source)
+    - [get_filtered_columns_in_relation](#get_filtered_columns_in_relation-source)
     - [get_relations_by_pattern](#get_relations_by_pattern-source)
     - [get_relations_by_prefix](#get_relations_by_prefix-source)
     - [get_query_results_as_dict](#get_query_results_as_dict-source)
@@ -544,7 +545,7 @@ These macros run a query and return the results of the query as objects. They ar
 #### get_column_values ([source](macros/sql/get_column_values.sql))
 This macro returns the unique values for a column in a given [relation](https://docs.getdbt.com/docs/writing-code-in-dbt/class-reference/#relation) as an array.
 
-Arguments:
+**Args:**
 - `table` (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
 - `column` (required): The name of the column you wish to find the column values of
 - `order_by` (optional, default=`'count(*) desc'`): How the results should be ordered. The default is to order by `count(*) desc`, i.e. decreasing frequency. Setting this as `'my_column'` will sort alphabetically, while `'min(created_at)'` will sort by when thevalue was first observed.
@@ -585,6 +586,28 @@ Arguments:
 ...
 ```
 
+#### get_filtered_columns_in_relation ([source](macros/sql/get_filtered_columns_in_relation.sql))
+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), (i.e. not from a CTE)
+- optionally exclude columns
+- the input values are not case-sensitive (input uppercase or lowercase and it will work!)
+> Note: The native [`adapter.get_columns_in_relation` macro](https://docs.getdbt.com/reference/dbt-jinja-functions/adapter#get_columns_in_relation) allows you 
+to pull column names in a non-filtered fashion, also bringing along with it other (potentially unwanted) information, such as dtype, char_size, numeric_precision, etc.
+
+**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. (case-insensitive)
+
+**Usage:**
+```sql
+-- Returns a list of the columns from a relation, so you can then iterate in a for loop
+{% set column_names = dbt_utils.get_filtered_columns_in_relation(from=ref('your_model'), except=["field_1", "field_2"]) %}
+...
+{% for column_name in column_names %}
+    max({{ column_name }}) ... as max_'{{ column_name }}',
+{% endfor %}
+...
+```
+
 #### get_relations_by_pattern ([source](macros/sql/get_relations_by_pattern.sql))
 Returns a list of [Relations](https://docs.getdbt.com/docs/writing-code-in-dbt/class-reference/#relation)
 that match a given schema- or table-name pattern.
@@ -748,9 +771,19 @@ group by 1,2,3
 ```
 
 #### star ([source](macros/sql/star.sql))
-This macro generates a comma-separated list of all fields that exist in the `from` relation, excluding any fields listed in the `except` argument. The construction is identical to `select * from {{ref('my_model')}}`, replacing star (`*`) with the star macro. This macro also has an optional `relation_alias` argument that will prefix all generated fields with an alias (`relation_alias`.`field_name`). 
+This macro generates a comma-separated list of all fields that exist in the `from` relation, excluding any fields 
+listed in the `except` argument. The construction is identical to `select * from {{ref('my_model')}}`, replacing star (`*`) with 
+the star macro. 
+This macro also has an optional `relation_alias` argument that will prefix all generated fields with an alias (`relation_alias`.`field_name`). 
+The macro also has optional `prefix` and `suffix` arguments. When one or both are provided, they will be concatenated onto each field's alias 
+in the output (`prefix` ~ `field_name` ~ `suffix`). NB: This prevents the output from being used in any context other than a select statement.
 
-The macro also has optional `prefix` and `suffix` arguments. When one or both are provided, they will be concatenated onto each field's alias in the output (`prefix` ~ `field_name` ~ `suffix`). NB: This prevents the output from being used in any context other than a select statement.
+**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. (case-insensitive)
+- `relation_alias` (optional, default=`''`): will prefix all generated fields with an alias (`relation_alias`.`field_name`). 
+- `prefix` (optional, default=`''`): will prefix the output `field_name` (`field_name as prefix_field_name`). 
+- `suffix` (optional, default=`''`): will suffix the output `field_name` (`field_name as field_name_suffix`). 
 
 **Usage:**
 ```sql
@@ -767,6 +800,13 @@ from {{ ref('my_model') }}
 
 ```
 
+```sql
+select
+{{ dbt_utils.star(from=ref('my_model'), except=["exclude_field_1", "exclude_field_2"], prefix="max_") }}
+from {{ ref('my_model') }}
+
+```
+
 #### union_relations ([source](macros/sql/union.sql))
 
 This macro unions together an array of [Relations](https://docs.getdbt.com/docs/writing-code-in-dbt/class-reference/#relation),

integration_tests/data/sql/data_filtered_columns_in_relation.csv

@@ -0,0 +1,4 @@
+field_1,field_2,field_3
+a,b,c
+d,e,f
+g,h,i

integration_tests/data/sql/data_filtered_columns_in_relation_expected.csv

@@ -0,0 +1,2 @@
+field_2,field_3
+h,i

integration_tests/macros/assert_equal_values.sql

@@ -0,0 +1,32 @@
+{% macro assert_equal_values(actual_object, expected_object) %}
+{% if not execute %}
+
+    {# pass #}
+
+{% elif actual_object != expected_object %}
+
+    {% set msg %}
+    Expected did not match actual
+
+    -----------
+    Actual:
+    -----------
+    --->{{ actual_object }}<---
+
+    -----------
+    Expected:
+    -----------
+    --->{{ expected_object }}<---
+
+    {% endset %}
+
+    {{ log(msg, info=True) }}
+
+    select 'fail'
+
+{% else %}
+
+    select 'ok' {{ limit_zero() }}
+
+{% endif %}
+{% endmacro %}

integration_tests/models/sql/schema.yml

@@ -50,6 +50,11 @@ models:
               values:
                 - '5'
 
+  - name: test_get_filtered_columns_in_relation
+    tests:
+      - dbt_utils.equality:
+          compare_model: ref('data_filtered_columns_in_relation_expected')
+
   - name: test_get_relations_by_prefix_and_union
     columns:
       - name: event
@@ -121,6 +126,11 @@ models:
       - dbt_utils.equality:
           compare_model: ref('data_star_aggregate_expected')
 
+  - name: test_star_uppercase
+    tests:
+      - dbt_utils.equality:
+          compare_model: ref('data_star_expected')
+
   - name: test_surrogate_key
     tests:
       - assert_equal:

integration_tests/models/sql/test_get_filtered_columns_in_relation.sql

@@ -0,0 +1,16 @@
+{% set exclude_field = 'field_1' %}
+{% set column_names = dbt_utils.get_filtered_columns_in_relation(from= ref('data_filtered_columns_in_relation'), except=[exclude_field]) %}
+
+with data as (
+
+    select
+
+        {% for column_name in column_names %}
+            max({{ column_name }}) as {{ column_name }} {% if not loop.last %},{% endif %}
+        {% endfor %}
+
+    from {{ ref('data_filtered_columns_in_relation') }}
+
+)
+
+select * from data

integration_tests/models/sql/test_star_uppercase.sql

@@ -0,0 +1,13 @@
+{% set exclude_field = 'FIELD_3' %}
+
+
+with data as (
+
+    select
+        {{ dbt_utils.star(from=ref('data_star'), except=[exclude_field]) }}
+
+    from {{ ref('data_star') }}
+
+)
+
+select * from data

macros/sql/get_filtered_columns_in_relation.sql

@@ -0,0 +1,25 @@
+{% macro get_filtered_columns_in_relation(from, except=[]) -%}
+    {{ return(adapter.dispatch('get_filtered_columns_in_relation', 'dbt_utils')(from, except)) }}
+{% endmacro %}
+
+{% macro default__get_filtered_columns_in_relation(from, except=[]) -%}
+    {%- do dbt_utils._is_relation(from, 'get_filtered_columns_in_relation') -%}
+    {%- do dbt_utils._is_ephemeral(from, 'get_filtered_columns_in_relation') -%}
+
+    {# -- Prevent querying of db in parsing mode. This works because this macro does not create any new refs. #}
+    {%- if not execute -%}
+        {{ 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 %}
+
+    {{ return(include_cols) }}
+
+{%- endmacro %}

macros/sql/star.sql

@@ -11,20 +11,9 @@
         {{ return('') }}
     {% endif %}
 
-    {%- set include_cols = [] %}
-    {%- set cols = adapter.get_columns_in_relation(from) -%}
-    {%- set except = except | map("lower") | list %}
-    {%- for col in cols -%}
+    {%- for col in dbt_utils.get_filtered_columns_in_relation(from, except) %}
 
-        {%- if col.column|lower not in except -%}
-            {% do include_cols.append(col.column) %}
-
-        {%- endif %}
-    {%- endfor %}
-
-    {%- for col in include_cols %}
-
-        {%- if relation_alias %}{{ relation_alias }}.{% else %}{%- endif -%}{{ adapter.quote(col)|trim }} {%- if prefix!='' or suffix!='' -%} as {{ adapter.quote(prefix ~ col ~ suffix)|trim }} {%- endif -%}
+        {%- 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 %}
 
     {%- endfor -%}