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Entities are defined using a JSON Schema that describes the data structure and validation rules.

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Basic schema structure

Entity schemas are defined in JSON files in your project’s entities directory. By default, this is base44/entities/, but you can customize the path in your project configuration. The filename determines the entity name. For example, Task.json creates a Task entity. Here’s an entity schema template: 
{
  "name": "my_entity",
  "type": "object",
  "title": "My Entity",
  "description": "Description of what this entity represents",
  "properties": {
    "<field_name>": {
      "type": "<field_type>",
      "<option>": "<value>"
    }
  },
  "required": ["<field_name>"]
}

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Built-in fields

Every entity record automatically includes the following fields. Don’t define fields with these names in your schema.
FieldTypeDescription
idstringUnique identifier for the record
created_datedatetimeWhen the record was created
updated_datedatetimeWhen the record was last updated
created_bystringEmail of the user who created the record
created_by_idstringID of the user who created the record
is_deleted (internal)booleanSoft delete flag
deleted_date (internal)datetimeWhen the record was deleted
is_sample (internal)booleanWhether the record is sample data
entity_name (internal)stringName of the entity type
app_id (internal)stringApp ID
environment (internal)stringEither prod or dev
Internal fields aren’t returned in API responses but can be referenced in security rules.

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Schema fields

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name
string
String identifier for the entity.
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type
string
required
Must be "object".
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title
string
User-friendly display name.
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description
string
Description of what the entity represents.
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properties
object
required
Object containing your field definitions. Each field has a type and optional validation rules.

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Field types

Entities support various field types to define different kinds of data you can store: string, integer, number, boolean, array, and object. Each field inside properties requires a type. Based on the type, you can add validation options.

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String fields

String fields support these options:
  • minLength / maxLength: Control minimum and maximum character count.
  • pattern: Regular expression for custom validation.
  • format: Predefined formats. Supported values:
    • "date"
    • "date-time"
    • "time"
    • "email"
    • "uri"
    • "hostname"
    • "ipv4"
    • "ipv6"
    • "uuid"
  • enum: Restrict to specific allowed values. Define as an array: ["value1", "value2", "value3"].
  • default: Default value if none provided.

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Integer fields

Integer fields support these options:
  • minimum / maximum: Set inclusive lower/upper bounds.
  • default: Default value if none provided.

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Number fields

Number fields support these options:
  • minimum / maximum: Set inclusive lower/upper bounds.
  • default: Default value if none provided.

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Boolean fields

Boolean fields support these options:
  • default: Default value if none provided.

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Array fields

Array fields support these options:
  • items: Define the type/schema for array elements.
  • default: Default array value if none provided.

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Object fields

Object fields support these options:
  • properties: Define the fields within the object.
  • required: List of required property names.

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Required fields

Specify which fields must be provided: 
{
  "required": ["title", "email"]
}

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Complete example

Here’s a complete entity schema: 
{
  "name": "Task",
  "type": "object",
  "title": "Task",
  "description": "A task item with priority, due date, and completion status",
  "properties": {
    "title": {
      "type": "string",
      "minLength": 1,
      "maxLength": 200
    },
    "description": {
      "type": "string",
      "maxLength": 1000
    },
    "priority": {
      "type": "string",
      "enum": ["low", "medium", "high"],
      "default": "medium"
    },
    "completed": {
      "type": "boolean",
      "default": false
    },
    "due_date": {
      "type": "string",
      "format": "date"
    },
    "tags": {
      "type": "array",
      "items": {"type": "string"}
    }
  },
  "required": ["title"]
}

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Deploying entities

After defining your entity schema, deploy it to Base44 using entities push. Entities are also deployed automatically when you run the deploy command to deploy your entire project. Once deployed, you can interact with your entities using the SDK’s entities module. Deployed entity schemas can be viewed in the dashboard in the Data section.

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See also