optional.sql

{%- macro optional(relation, optional_column, data_type) -%}

{# When the relation is not defined (optional tables), set the columns and relation to empty #}
{%- if load_relation(relation) is none -%}
    {%- set columns = [] -%}
    {%- set relation = null -%}
{%- else -%}
    {%- set columns = adapter.get_columns_in_relation(relation) -%}
{%- endif -%}

{# Check if relation is a source based on whether the relation's schema and identifier is defined as source. 
Only check when relation exists to prevent dbt compile errors. #}
{%- set ns = namespace(is_source_relation = false) -%}

{% if execute and relation != null %}
    {% for node in graph.sources.values() -%}
        {% if node.schema == relation.schema and node.identifier == relation.identifier %}
            {% set ns.is_source_relation = true %}
        {% endif %}
    {% endfor %}
{% endif %}

{# Create list of column names.#}
{%- set column_names = [] -%}
{%- for column in columns -%}
        {%- set column_names = column_names.append('"' + column.name + '"') -%}
{%- endfor -%}

{# When the column is in the list, use the column, otherwise create the column with null values.#}
{%- if optional_column in column_names -%}
    {% set column_value = optional_column -%}
{%- else -%}
    {% set column_value = 'null' -%}
{%- endif -%}

{# Apply casting when relation is a source or when the field doesn't exist and is being created. #}
{% if ns.is_source_relation or column_value == 'null' %}
    {%- if data_type == 'boolean' -%}
        {{ pm_utils.to_boolean(column_value, relation) }}
    {%- elif data_type == 'date' -%}
        {{ pm_utils.to_date(column_value, relation) }}
    {%- elif data_type == 'double' -%}
        {{ pm_utils.to_double(column_value, relation) }}
    {%- elif data_type == 'integer' -%}
        {{ pm_utils.to_integer(column_value, relation) }}
    {%- elif data_type == 'datetime' -%}
        {{ pm_utils.to_timestamp(column_value, relation) }}
    {%- elif data_type == 'text' -%}
        {{ pm_utils.to_varchar(column_value) }}
    {%- elif data_type == 'id' -%}
        {% if optional_column in column_names %}
            {{ pm_utils.to_integer(column_value, relation) }}
        {% else %}
            row_number() over (order by (select null))
        {% endif %}
    {%- else -%}
        {{ pm_utils.to_varchar(column_value) }}
    {%- endif -%}
{# Don't apply casting when relation is not a source. Casting should already have been done in a previous transformation step. #}
{%- else -%}
    {{ column_value }}
{%- endif -%}

{%- endmacro -%}