Templating

DataSQRL uses the Mustache templating engine to substitute configuration variables in SQRL scripts, making them reusable and configurable without modifying the code.

How It Works

Variables in your SQRL script are wrapped in double curly braces {{variableName}}. When DataSQRL compiles the script, it replaces these placeholders with values defined in the script.config section of your package.json configuration file.

Example

Configuration File (package.json)

{
  "version": "1",
  "script": {
    "main": "query.sqrl",
    "config": {
      "tableName": "Users",
      "idColumn": "user_id",
      "timestampColumn": "created_at",
      "minAge": 18
    }
  }
}

SQRL Script (query.sqrl)

IMPORT tables.{{tableName}};

FilteredUsers :=
SELECT {{idColumn}},
       name,
       {{timestampColumn}}
FROM {{tableName}}
WHERE age >= {{minAge}};

After Substitution

When DataSQRL processes this script, it replaces all {{variableName}} placeholders:

IMPORT tables.Users;

FilteredUsers :=
SELECT user_id,
       name,
       created_at
FROM Users
WHERE age >= 18;

Benefits

1. Reusability: The same SQRL script can work with different tables and columns by changing the config
2. Maintainability: Configuration is centralized in one place (package.json)
3. Type Safety: You can specify types like partitionColType: "bigint" and use them in the script
4. Environment-Specific: Easy to have different configs for dev, test, and production

Special Variables

DataSQRL also provides built-in variables:

• ${DEPLOYMENT_ID}: Unique identifier for each deployment
• ${DEPLOYMENT_TIMESTAMP}: Timestamp when the job was deployed

These are substituted at deployment time and are useful for tracking and versioning.