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2. Configure the Squirrels Project File

Go to the squirrels.yml file. This is the Squirrels project file to configure most of the properties of the Squirrels project in yaml.

In this tutorial, we will focus on the project_variables, connections, and datasets sections.

Setting the Project Variables​

The project variables name and major_version are required. The label is optional, and will use the name if not specified. In additional to those, you are free to add any of your own project variable.

In this tutorial, we will be making dataset APIs related to historical weather data. Change the name to weather and label to Weather Analytics (we will leave major_version as is).

The project_variables section should now look like this:

project_variables:
  name: weather
  label: Weather Analytics
  major_version: 1

Setting the Database Connections​

This section is where we set all the database connection details that we need. We provide a list of connection names here and refer to them in other files. The connection name default must be provided for models that don't set a connection name explicitly.

Under default, change the url to sqlite:///./database/weather.db.

tip

You can also use the Jinja's double curly brackets syntax to substitute environment variables defined in the environcfg.yml file.

The syntax for the URL uses sqlalchemy database URLs. Since sqlite databases don't require a username and password, the credential field can be either set to null or omitted entirely. More details on setting and using credential keys and connections can be found at Database Connections.

The connections section should now look like this:

connections:
  - name: default
    credential: null
    url: sqlite:///./database/weather.db

Defining the Datasets​

This section is where we define the attributes for all datasets created by the Squirrels project. Every dataset defined will have their own "parameters API" and "dataset result API".

Change the first dataset name to weather_by_time and label to Weather by Time of Year. Remove all parameters except "group_by", and rename it to "group_by_dim". Fields scope and traits can be omitted.

Remove the second dataset.

The datasets section should now look like this:

datasets:
  - name: weather_by_time
    label: Weather by Time of Year
    parameters:
      - group_by_dim

Every dataset name that's set in the datasets section must also have a matching file name somewhere in models folder (unless a model field is specified). At this point, we can rename the models files:

  1. In the models/federates folder, rename dataset_example.sql to weather_by_time.sql.
  2. In the models/dbviews folder, rename database_view1.sql to aggr_weather_metrics.sql.

More details on the Squirrels project file can be found at Squirrels Project File.