Merge pull request dbt-labs#152 from emilieschario/master

Resolve "get_column_values returns an error if passed a `ref`, but the model has not been previously built"

README.md

@@ -216,11 +216,12 @@ models:
 ### SQL helpers
 #### get_column_values ([source](macros/sql/get_column_values.sql))
 This macro returns the unique values for a column in a given table.
+It takes an options `default` argument for compiling when relation does not already exist. 
 
 Usage:
 ```
 -- Returns a list of the top 50 states in the `users` table
-{% set states = dbt_utils.get_column_values(table=ref('users'), column='state', max_records=50) %}
+{% set states = dbt_utils.get_column_values(table=ref('users'), column='state', max_records=50, default=[]) %}
 
 {% for state in states %}
     ...

integration_tests/Makefile

@@ -1,20 +1,24 @@
 
 test-postgres:
+	dbt compile --target postgres
 	dbt seed --target postgres --full-refresh
 	dbt run --target postgres --full-refresh --exclude test_insert_by_period
 	dbt test --target postgres --exclude test_insert_by_period
 
 test-redshift:
+	dbt compile --target redshift
 	dbt seed --target redshift --full-refresh
 	dbt run --target redshift --full-refresh
 	dbt test --target redshift
 
 test-snowflake:
+	dbt compile --target snowflake
 	dbt seed --target snowflake --full-refresh
 	dbt run --target snowflake --full-refresh
 	dbt test --target snowflake
 
 test-bigquery:
+	dbt compile --target bigquery
 	dbt seed --target bigquery --full-refresh
 	dbt run --target bigquery --full-refresh
 	dbt test --target bigquery

integration_tests/models/sql/test_get_column_values.sql

@@ -1,11 +1,10 @@
 
-{% set columns = dbt_utils.get_column_values(ref('data_get_column_values'), 'field') %}
+{% set columns = dbt_utils.get_column_values(ref('data_get_column_values'), 'field', default = []) %}
 
 
 {% if target.type == 'snowflake' %}
 
 select
-    {% set columns = columns if columns is iterable else [] %}
     {% for column in columns -%}
 
         sum(case when field = '{{ column }}' then 1 else 0 end) as count_{{ column }}
@@ -18,7 +17,6 @@ from {{ ref('data_get_column_values') }}
 {% else %}
 
 select
-    {% set columns = columns if columns is iterable else [] %}
     {% for column in columns -%}
 
         {{dbt_utils.safe_cast("sum(case when field = '" ~ column ~ "' then 1 else 0 end)", dbt_utils.type_string()) }} as count_{{ column }}

macros/sql/get_column_values.sql

@@ -1,4 +1,3 @@
-
 {#
 This macro fetches the unique values for `column` in the table `table`
 
@@ -11,19 +10,43 @@ Returns:
     A list of distinct values for the specified columns
 #}
 
-{% macro get_column_values(table, column, max_records=none) -%}
+{% macro get_column_values(table, column, max_records=none, default=none) -%}
+
+{#-- Prevent querying of db in parsing mode. This works because this macro does not create any new refs. #}
+    {%- if not execute -%}
+        {{ return('') }}
+    {% endif %}
+{#--  #}
+
+    {%- set target_relation = adapter.get_relation(database=table.database,
+                                          schema=table.schema,
+                                         identifier=table.identifier) -%}
+
+    {%- call statement('get_column_values', fetch_result=true) %}
+
+        {%- if not target_relation and default is none -%}
+
+          {{ exceptions.raise_compiler_error("In get_column_values(): relation " ~ table ~ " does not exist and no default value was provided.") }}
+
+        {%- elif not target_relation and default is not none -%}
+
+          {{ log("Relation " ~ table ~ " does not exist. Returning the default value: " ~ default) }}
+
+          {{ return(default) }}
+
+        {%- else -%}
 
-    {%- call statement('get_column_values', fetch_result=True) %}
+            select
+                {{ column }} as value
 
-        select
-            {{ column }} as value
+            from {{ target_relation }}
+            group by 1
+            order by count(*) desc
 
-        from {{ table }}
-        group by 1
-        order by count(*) desc
+            {% if max_records is not none %}
+            limit {{ max_records }}
+            {% endif %}
 
-        {% if max_records is not none %}
-        limit {{ max_records }}
         {% endif %}
 
     {%- endcall -%}
@@ -34,7 +57,7 @@ Returns:
         {%- set values = value_list['data'] | map(attribute=0) | list %}
         {{ return(values) }}
     {%- else -%}
-        {{ return([]) }}
+        {{ return(default) }}
     {%- endif -%}
 
 {%- endmacro %}