dbt Constraints / model contracts

.changes/unreleased/Features-20221219-164808.yaml

@@ -0,0 +1,8 @@
+kind: Features
+body: 'Support for data types constraints in Snowflake following the dbt Core feature
+  #6271'
+time: 2022-12-19T16:48:08.771806+01:00
+custom:
+  Author: b-per
+  Issue: "365"
+  PR: "341"

dbt/include/snowflake/macros/adapters.sql

@@ -21,7 +21,12 @@
           temporary
         {%- elif transient -%}
           transient
-        {%- endif %} table {{ relation }} {% if copy_grants and not temporary -%} copy grants {%- endif %} as
+        {%- endif %} table {{ relation }}
+        {% if config.get('constraints_enabled', False) %}
+          {{ get_assert_columns_equivalent(sql) }}
+          {{ get_columns_spec_ddl() }}
+        {% endif %}
+        {% if copy_grants and not temporary -%} copy grants {%- endif %} as
         (
           {%- if cluster_by_string is not none -%}
             select * from(

dbt/include/snowflake/macros/utils/get_columns_spec_ddl.sql

@@ -0,0 +1,16 @@
+{% macro snowflake__get_columns_spec_ddl() %}
+  {# loop through user_provided_columns to create DDL with data types and constraints #}
+  {%- set ns = namespace(at_least_one_check=False) -%}
+  {%- set user_provided_columns = model['columns'] -%}
+  (
+  {% for i in user_provided_columns -%}
+    {%- set col = user_provided_columns[i] -%}
+    {% set constraints = col['constraints'] -%}
+    {%- set ns.at_least_one_check = ns.at_least_one_check or col['constraints_check'] %}
+    {{ col['name'] }} {{ col['data_type'] }} {% for x in constraints %} {{ x or "" }} {% endfor %} {{ "," if not loop.last }}
+  {%- endfor %}
+)
+  {%- if ns.at_least_one_check -%}
+    {{exceptions.warn("We noticed you have `constraints_check` configs, these are NOT compatible with Snowflake and will be ignored")}}
+  {%- endif %}
+{% endmacro %}

tests/functional/adapter/test_constraints.py

@@ -0,0 +1,33 @@
+import pytest
+from dbt.tests.util import relation_from_name
+from dbt.tests.adapter.constraints.test_constraints import (
+    BaseConstraintsColumnsEqual,
+    BaseConstraintsRuntimeEnforcement
+)
+
+_expected_sql_snowflake = """
+create or replace transient table {0} (
+    id integer not null primary key ,
+    color text ,
+    date_day date
+) as (
+    select
+        1 as id,
+        'blue' as color,
+        cast('2019-01-01' as date) as date_day
+);
+"""
+
+class TestSnowflakeConstraintsColumnsEqual(BaseConstraintsColumnsEqual):
+    pass
+
+
+class TestSnowflakeConstraintsRuntimeEnforcement(BaseConstraintsRuntimeEnforcement):
+    @pytest.fixture(scope="class")
+    def expected_sql(self, project):
+        relation = relation_from_name(project.adapter, "my_model")
+        return _expected_sql_snowflake.format(relation)
+
+    @pytest.fixture(scope="class")
+    def expected_error_messages(self):
+        return ["NULL result in a non-nullable column"]