dbt Constraints / model contracts

.changes/unreleased/Features-20221220-193731.yaml

@@ -0,0 +1,7 @@
+kind: Features
+body: 'dbt-constraints support for BigQuery as per dbt-core issue #1358'
+time: 2022-12-20T19:37:31.982821+01:00
+custom:
+  Author: victoriapm
+  Issue: "444"
+  PR: "426"

dbt/include/bigquery/macros/adapters.sql

@@ -52,8 +52,13 @@
     {{ sql_header if sql_header is not none }}
 
     create or replace table {{ relation }}
+      {% if config.get('constraints_enabled', False) %}
+        {{ get_assert_columns_equivalent(sql) }}
+        {{ get_columns_spec_ddl() }}
+      {% endif %}
     {{ partition_by(partition_config) }}
     {{ cluster_by(raw_cluster_by) }}
+
     {{ bigquery_table_options(config, model, temporary) }}
     as (
       {{ compiled_code }}

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

@@ -0,0 +1,16 @@
+{% macro bigquery__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 BigQuery and will be ignored")}}
+  {%- endif %}
+{% endmacro %}

dev-requirements.txt

@@ -2,7 +2,6 @@
 # TODO: how to automate switching from develop to version branches?
 git+https://github.com/dbt-labs/dbt-core.git#egg=dbt-core&subdirectory=core
 git+https://github.com/dbt-labs/dbt-core.git#egg=dbt-tests-adapter&subdirectory=tests/adapter
-
 black~=22.8.0
 bumpversion~=0.6.0
 flake8

tests/functional/adapter/test_constraints.py

@@ -0,0 +1,59 @@
+import pytest
+from dbt.tests.util import relation_from_name
+from dbt.tests.adapter.constraints.test_constraints import (
+    BaseConstraintsColumnsEqual,
+    BaseConstraintsRuntimeEnforcement
+)
+from dbt.tests.adapter.constraints.fixtures import (
+    my_model_sql,
+    my_model_wrong_order_sql,
+    my_model_wrong_name_sql,
+    model_schema_yml,
+)
+
+_expected_sql_bigquery = """
+create or replace table {0} (
+    id integer  not null    ,
+    color string  ,
+    date_day date
+)
+OPTIONS()
+as (
+    select
+        1 as id,
+        'blue' as color,
+        cast('2019-01-01' as date) as date_day
+);
+"""
+
+# Different on BigQuery:
+# - does not support a data type named 'text' (TODO handle this via type translation/aliasing!)
+# - raises an explicit error, if you try to set a primary key constraint, because it's not enforced
+constraints_yml = model_schema_yml.replace("text", "string").replace("primary key", "")
+
+class TestBigQueryConstraintsColumnsEqual(BaseConstraintsColumnsEqual):
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "my_model_wrong_order.sql": my_model_wrong_order_sql,
+            "my_model_wrong_name.sql": my_model_wrong_name_sql,
+            "constraints_schema.yml": constraints_yml,
+        }
+
+
+class TestBigQueryConstraintsRuntimeEnforcement(BaseConstraintsRuntimeEnforcement):
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "my_model.sql": my_model_sql,
+            "constraints_schema.yml": constraints_yml,
+        }
+
+    @pytest.fixture(scope="class")
+    def expected_sql(self, project):
+        relation = relation_from_name(project.adapter, "my_model")
+        return _expected_sql_bigquery.format(relation)
+
+    @pytest.fixture(scope="class")
+    def expected_error_messages(self):
+        return ["Required field id cannot be null"]