Add default to event counts string query (Close #26)

CHANGELOG

@@ -7,6 +7,9 @@ XXX
 - Add new passthrough aggregations to the views, sessions, and users table, enabled using `snowplow__view/session/user_aggregations`
 - Reorder and add some additional context fields to derived tables (non-breaking change)
 
+## Fixes
+- Fix a bug where if you ran the package in a period with no data, and had list all events enabled, the package would error rather than complete
+
 ## Under the hood
 - Prefix all macro calls with package name for easier customization
 - Use macros for grouped fields (e.g. contexts) where possible

integration_tests/.scripts/integration_test.sh

@@ -26,6 +26,10 @@ for db in ${DATABASES[@]}; do
   echo "Snowplow unified integration tests: Seeding data"
   eval "dbt seed --full-refresh --target $db" || exit 1;
 
+  echo "Snowplow unified integration tests: Try run without data"
+  eval "dbt run --full-refresh --vars '{snowplow__allow_refresh: true, snowplow__backfill_limit_days: 1, snowplow__enable_cwv: false, snowplow__start_date: 2010-01-01}' --target $db" || exit 1;
+
+
   echo "Snowplow unified integration tests: Conversions"
   eval "dbt run --full-refresh --select +snowplow_unified_conversions snowplow_unified_integration_tests.source --vars '{snowplow__allow_refresh: true, snowplow__backfill_limit_days: 220, snowplow__enable_cwv: false, snowplow__enable_conversions: true}' --target $db" || exit 1;
 

macros/field_definitions/event_counts_string_query.sql

@@ -10,7 +10,7 @@ You may obtain a copy of the Snowplow Personal and Academic License Version 1.0
 {% endmacro %}
 
 {% macro default__event_counts_string_query() %}
-  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name') %}
+  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name', default = []) %}
   {# Loop over every event_name in this run, create a json string of the name and count ONLY if there are events with that name in the session (otherwise empty string),
   then trim off the last comma (cannot use loop.first/last because first/last entry may not have any events for that session)
   #}
@@ -24,7 +24,7 @@ You may obtain a copy of the Snowplow Personal and Academic License Version 1.0
 {% endmacro %}
 
 {% macro bigquery__event_counts_string_query() %}
-  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name') %}
+  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name', default = []) %}
   {# Loop over every event_name in this run, create a json string of the name and count ONLY if there are events with that name in the session (otherwise empty string),
   then trim off the last comma (cannot use loop.first/last because first/last entry may not have any events for that session)
   #}
@@ -39,18 +39,22 @@ You may obtain a copy of the Snowplow Personal and Academic License Version 1.0
 
 {% macro spark__event_counts_string_query() %}
 
-  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_base_events_this_run'), 'event_name', order_by = 'event_name') %}
+  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_base_events_this_run'), 'event_name', order_by = 'event_name', default = []) %}
   {# Loop over every event_name in this run, create a map of the name and count, later filter for only events with that name in the session #}
-  map(
-  {%- for event_name in event_names %}
-      '{{event_name}}',  sum(case when event_name = '{{event_name}}' then 1 else 0 end){% if not loop.last %},{% endif %}
-  {%- endfor -%}
-  )
+  {% if event_names %}
+    map(
+    {%- for event_name in event_names %}
+        '{{event_name}}',  sum(case when event_name = '{{event_name}}' then 1 else 0 end){% if not loop.last %},{% endif %}
+    {%- endfor -%}
+    )
+  {% else %}
+    cast(null as map<string, int>)
+  {% endif %}
 
 {% endmacro %}
 
 {% macro postgres__event_counts_string_query() %}
-  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name') %}
+  {% set event_names =  dbt_utils.get_column_values(ref('snowplow_unified_events_this_run'), 'event_name', order_by = 'event_name', default = []) %}
   {# Loop over every event_name in this run, create a json string of the name and count ONLY if there are events with that name in the session (otherwise empty string),
   then trim off the last comma (cannot use loop.first/last because first/last entry may not have any events for that session)
   #}