Skip to content

Commit

Permalink
Browse files Browse the repository at this point in the history
…xemplar into bethanyhipple-dbtlabs-patch-1
  • Loading branch information
Bethany Hipple committed Jul 30, 2024
2 parents 17dbd73 + f348361 commit f297dae
Showing 1 changed file with 91 additions and 0 deletions.
91 changes: 91 additions & 0 deletions _samples/model_governance/how_contracts_work_columns_spec_ddl.sql
Original file line number Diff line number Diff line change
@@ -0,0 +1,91 @@
--this is the macro dbt uses under the hood to enforce contracts. as-is in this
-- project, it does not affect anything. it's here for display only.
{%- macro get_table_columns_and_constraints() -%}
{{ adapter.dispatch('get_table_columns_and_constraints', 'dbt')() }}
{%- endmacro -%}

{% macro default__get_table_columns_and_constraints() -%}
{{ return(table_columns_and_constraints()) }}
{%- endmacro %}

{% macro table_columns_and_constraints() %}
{# loop through user_provided_columns to create DDL with data types and constraints #}
{%- set raw_column_constraints = adapter.render_raw_columns_constraints(raw_columns=model['columns']) -%}
{%- set raw_model_constraints = adapter.render_raw_model_constraints(raw_constraints=model['constraints']) -%}
(
{% for c in raw_column_constraints -%}
{{ c }}{{ "," if not loop.last or raw_model_constraints }}
{% endfor %}
{% for c in raw_model_constraints -%}
{{ c }}{{ "," if not loop.last }}
{% endfor -%}
)
{% endmacro %}

{%- macro get_assert_columns_equivalent(sql) -%}
{{ adapter.dispatch('get_assert_columns_equivalent', 'dbt')(sql) }}
{%- endmacro -%}

{% macro default__get_assert_columns_equivalent(sql) -%}
{{ return(assert_columns_equivalent(sql)) }}
{%- endmacro %}

{#
Compares the column schema provided by a model's sql file to the column schema provided by a model's schema file.
If any differences in name, data_type or number of columns exist between the two schemas, raises a compiler error
#}
{% macro assert_columns_equivalent(sql) %}

{#-- First ensure the user has defined 'columns' in yaml specification --#}
{%- set user_defined_columns = model['columns'] -%}
{%- if not user_defined_columns -%}
{{ exceptions.raise_contract_error([], []) }}
{%- endif -%}

{#-- Obtain the column schema provided by sql file. #}
{%- set sql_file_provided_columns = get_column_schema_from_query(sql, config.get('sql_header', none)) -%}
{#--Obtain the column schema provided by the schema file by generating an 'empty schema' query from the model's columns. #}
{%- set schema_file_provided_columns = get_column_schema_from_query(get_empty_schema_sql(user_defined_columns)) -%}

{#-- create dictionaries with name and formatted data type and strings for exception #}
{%- set sql_columns = format_columns(sql_file_provided_columns) -%}
{%- set yaml_columns = format_columns(schema_file_provided_columns) -%}

{%- if sql_columns|length != yaml_columns|length -%}
{%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
{%- endif -%}

{%- for sql_col in sql_columns -%}
{%- set yaml_col = [] -%}
{%- for this_col in yaml_columns -%}
{%- if this_col['name'] == sql_col['name'] -%}
{%- do yaml_col.append(this_col) -%}
{%- break -%}
{%- endif -%}
{%- endfor -%}
{%- if not yaml_col -%}
{#-- Column with name not found in yaml #}
{%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
{%- endif -%}
{%- if sql_col['formatted'] != yaml_col[0]['formatted'] -%}
{#-- Column data types don't match #}
{%- do exceptions.raise_contract_error(yaml_columns, sql_columns) -%}
{%- endif -%}
{%- endfor -%}

{% endmacro %}

{% macro format_columns(columns) %}
{% set formatted_columns = [] %}
{% for column in columns %}
{%- set formatted_column = adapter.dispatch('format_column', 'dbt')(column) -%}
{%- do formatted_columns.append(formatted_column) -%}
{% endfor %}
{{ return(formatted_columns) }}
{% endmacro %}

{% macro default__format_column(column) -%}
{% set data_type = column.dtype %}
{% set formatted = column.column.lower() ~ " " ~ data_type %}
{{ return({'name': column.name, 'data_type': data_type, 'formatted': formatted}) }}
{%- endmacro -%}

0 comments on commit f297dae

Please sign in to comment.