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Guides Overview

Learn common patterns and best practices for DataGeneration.

How-To Guides​

Step-by-step guides for specific tasks:

Patterns​

Learn how to handle advanced scenarios:

Best Practices​

Use Seeds for Reproducibility​

Generation gen = DslDataGenerator.create()
    .withSeed(123L)
    .fromJsonString(dsl)
    .generate();

Using seeds ensures the same data is generated every time, perfect for testing.

Enable Memory Optimization for Large Datasets​

For datasets with more than 100,000 items, enable memory optimization:

Generation gen = DslDataGenerator.create()
    .withMemoryOptimization()
    .fromJsonString(dsl)
    .generate();

Use Sequential References for Even Distribution​

When you want balanced relationships (e.g., equal employees per team):

{
  "teamId": {
    "ref": "teams[*].id",
    "sequential": true
  }
}

Leverage Weighted Choices for Realistic Data​

Use weights to match real-world probability distributions:

{
  "status": {
    "gen": "choice",
    "options": ["active", "inactive", "pending"],
    "weights": [70, 20, 10]
  }
}

Filter References to Enforce Business Rules​

Exclude specific values from references:

{
  "userId": {
    "ref": "users[*].id",
    "filter": [{"ref": "bannedUser.id"}]
  }
}

Use Conditional References for Field-Based Filtering​

Filter collections by field values before referencing:

{
  "orders": {
    "count": 50,
    "item": {
      "userId": {"ref": "users[status='active' and age>=21].id"},
      "productId": {"ref": "products[stock>0].id"}
    }
  }
}

Use Range References for Segmented Data​

Reference specific subsets by index:

{
  "regionalManagers": {
    "count": 4,
    "item": {
      "managedEmployeeId": {"ref": "employees[0:4].id"}
    }
  }
}

Common Patterns​

User-Order Relationship​

{
  "users": {
    "count": 5,
    "item": {
      "id": {"gen": "uuid"},
      "name": {"gen": "name.fullName"}
    }
  },
  "orders": {
    "count": 20,
    "item": {
      "id": {"gen": "uuid"},
      "userId": {"ref": "users[*].id"},
      "total": {"gen": "float", "min": 10, "max": 1000, "decimals": 2}
    }
  }
}

Hierarchical Data​

{
  "departments": {
    "count": 3,
    "item": {
      "id": {"gen": "uuid"},
      "name": {"gen": "company.industry"}
    }
  },
  "teams": {
    "count": 9,
    "item": {
      "id": {"gen": "uuid"},
      "name": {"gen": "lorem.word"},
      "departmentId": {"ref": "departments[*].id", "sequential": true}
    }
  },
  "employees": {
    "count": 30,
    "item": {
      "id": {"gen": "uuid"},
      "name": {"gen": "name.fullName"},
      "teamId": {"ref": "teams[*].id"}
    }
  }
}

Admin User Pattern​

{
  "users": {
    "count": 10,
    "item": {
      "id": {"gen": "uuid"},
      "email": {"gen": "internet.emailAddress"},
      "role": {"gen": "choice", "options": ["admin", "user"], "weights": [10, 90]}
    },
    "pick": {
      "admin": 0
    }
  },
  "auditLogs": {
    "count": 50,
    "item": {
      "id": {"gen": "uuid"},
      "userId": {
        "ref": "users[*].id",
        "filter": [{"ref": "admin.id"}]
      },
      "action": {"gen": "lorem.word"}
    }
  }
}

Next Steps​