add support for measures

Author: owlas

README.md

@@ -4,15 +4,16 @@ Use `dbt2looker` to generate Looker view files automatically from dbt models.
 
 **Features**
 
-* Auto-generates a Looker view per dbt model
-* Supports dbt model and column-level descriptions
-* Automatically maps raw column types to looker types
-* Creates dimension groups for datetime/timestamp/date types
-* Currently supports: BigQuery, Snowflake, Redshift (postgres to come)
+* **Column descriptions** synced to looker
+* **Dimension** for each column in dbt model
+* **Dimension groups** for datetime/timestamp/date columns
+* **Measures** defined through dbt column `metadata` [see below](#defining-measures)
+* Looker types
+* Warehouses: BigQuery, Snowflake, Redshift (postgres to come)
 
 [![demo](https://raw.githubusercontent.com/hubble-data/dbt2looker/main/docs/demo.gif)](https://asciinema.org/a/407407)
 
-### Usage
+## Quickstart
 
 Run `dbt2looker` in the root of your dbt project *after compiling looker docs*.
 
@@ -56,3 +57,22 @@ poetry install
 # Run
 poetry run dbt2looker
 ```
+
+## Defining measures
+
+You can define looker measures in your dbt `schema.yml` files. For example:
+
+```yaml
+models:
+  - name: pages
+    columns:
+      - name: url
+        description: "Page url"
+      - name: event_id
+        description: unique event id for page view
+        meta:
+          looker.com:  # looker config block for column
+             measures:
+               - name: Page views
+                 type: count
+```

dbt2looker/generator.py

@@ -164,13 +164,26 @@ def lookml_dimensions_from_model(model: models.DbtModel, adapter_type: models.Su
     ]
 
 
+def lookml_measures_from_model(model: models.DbtModel):
+    return [
+        {
+            'name': measure.name,
+            'type': measure.type.value,
+            'sql': f'${{TABLE}}.{column.name}',
+        }
+        for column in model.columns.values()
+        for measure in column.meta.looker.measures
+    ]
+
+
 def lookml_view_from_dbt_model(model: models.DbtModel, adapter_type: models.SupportedDbtAdapters):
     lookml = {
         'view': {
             'name': model.name,
             'sql_table_name': f'{model.database}.{model.db_schema}.{model.name}',
             'dimension_groups': lookml_dimension_groups_from_model(model, adapter_type),
             'dimensions': lookml_dimensions_from_model(model, adapter_type),
+            'measures': lookml_measures_from_model(model),
         }
     }
     contents = lkml.dump(lookml)

dbt2looker/models.py

@@ -3,6 +3,7 @@
 from pydantic import BaseModel, Field, PydanticValueError, validator
 
 
+# dbt2looker utility types
 class UnsupportedDbtAdapterError(PydanticValueError):
     code = 'unsupported_dbt_adapter'
     msg_template = '{wrong_value} is not a supported dbt adapter'
@@ -14,10 +15,33 @@ class SupportedDbtAdapters(str, Enum):
     snowflake = 'snowflake'
 
 
-class DbtProjectConfig(BaseModel):
+# Lookml types
+class LookerAggregateMeasures(str, Enum):
+    average = 'average'
+    average_distinct = 'average_distinct'
+    count = 'count'
+    count_distinct = 'count_distinct'
+    list = 'list'
+    max = 'max'
+    median = 'median'
+    median_distinct = 'median_distinct'
+    min = 'min'
+    percentile = 'percentile'
+    percentile_distinct = 'percentile_distinct'
+    sum = 'sum'
+    sum_distinct = 'sum_distinct'
+
+
+class Dbt2LookerMeasure(BaseModel):
     name: str
+    type: LookerAggregateMeasures
+
+
+class Dbt2LookerMeta(BaseModel):
+    measures: Optional[List[Dbt2LookerMeasure]] = []
 
 
+# Looker file types
 class LookViewFile(BaseModel):
     filename: str
     contents: str
@@ -28,10 +52,20 @@ class LookModelFile(BaseModel):
     contents: str
 
 
+# dbt config types
+class DbtProjectConfig(BaseModel):
+    name: str
+
+
+class DbtModelColumnMeta(BaseModel):
+    looker: Optional[Dbt2LookerMeta] = Field(Dbt2LookerMeta(), alias='looker.com')
+
+
 class DbtModelColumn(BaseModel):
     name: str
     description: str
     data_type: Optional[str]
+    meta: DbtModelColumnMeta
 
 
 class DbtNode(BaseModel):

example/lookml/views/pages.view

@@ -50,4 +50,9 @@ view: pages {
     sql: ${TABLE}.referring_domain ;;
     description: "Website domain of the referrer. e.g. google.com"
   }
+
+  measure: Page views {
+    type: count
+    sql: ${TABLE}.id ;;
+  }
 }

example/models/prod/pages.yml

@@ -7,6 +7,11 @@ models:
     columns:
       - name: id
         description: "The primary key for this table"
+        meta:
+          looker.com:
+            measures:
+              - name: Page views
+                type: count
         tests:
             - unique
             - not_null

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "dbt2looker"
-version = "0.5.2"
+version = "0.6.0"
 description = "Generate lookml view files from dbt models"
 authors = ["oliverlaslett <[email protected]>"]
 license = "MIT"