Schema JSON Format

Schemas are stored as the JSON content of pages in the Schema namespace (7474), and returned by the Schema REST endpoints. For terms like Schema and Property Definition, see the Glossary. A machine-readable JSON Schema for this format is at schemaContentSchema.json; it checks structure only. Per-type value constraints (options, ranges, string formats, uniqueItems) are enforced server-side and reported as validation codes.

Top-Level Structure

{
  "description": "Optional description of the schema",
  "propertyDefinitions": {
    "<property-name>": { ... },
    "<property-name>": { ... }
  }
}

Field	Type	Required	Description
description	string	No	Human-readable description of the schema
propertyDefinitions	object	Yes	Map of property names to property definition objects

Property Definition

Every property definition carries the common fields below plus the type-specific fields for its type.

Common Fields

Field	Type	Required	Default	Description
type	string	Yes	-	The property type. See Property Types.
description	string	No	""	Human-readable description of the property
required	boolean or object	No	false	Whether a value is required. Accepts a severity.
default	varies	No	null	Default value when none is provided

Constraint severity

Every Constraint carries a severity of error or warning, which decides whether violating it can block a write. Write a Constraint either as the bare value, which keeps the default warning, or as an object carrying the severity:

{
  "type": "number",
  "required": { "severity": "error" },
  "minimum": 0,
  "maximum": { "value": 100, "severity": "error" }
}

Boolean Constraints (required, uniqueItems) take no value in the object form — writing the object at all implies true. Every other Constraint carries its value under value, including options, whose value is the options array.

The Constraints that accept a severity are required, minimum, maximum, minLength, maxLength, uniqueItems, and options. Severity is a Constraint concept, so it does not apply to Display Attributes such as precision, where it is discarded, nor to the shape-declaring fields type, multiple, relation, and targetSchema, where it is rejected when the Schema is saved.

Canonical output emits the bare form whenever the severity is the default, so a Schema that sets no severities round-trips unchanged. Which violation each Constraint produces, and the fixed severities of the codes no Constraint backs, are covered in Validation codes.

Property Types

Text (text)

Plain text values.

Field	Type	Default	Description
multiple	boolean	false	Allow multiple values
uniqueItems	boolean	false	Reject duplicate values (only with multiple)
minLength	number	null	Minimum trimmed length of each value
maxLength	number	null	Maximum trimmed length of each value

{
  "type": "text",
  "multiple": true,
  "uniqueItems": true,
  "maxLength": 50
}

URL (url)

URL values.

Field	Type	Default	Description
multiple	boolean	false	Allow multiple values
uniqueItems	boolean	false	Reject duplicate values (only with multiple)

Number (number)

Numeric values (integer or float).

Field	Type	Default	Description
precision	number	null	Number of decimal places for display
minimum	number	null	Minimum allowed value (inclusive)
maximum	number	null	Maximum allowed value (inclusive)

{
  "type": "number",
  "minimum": 0,
  "maximum": 100,
  "precision": 2
}

Select (select)

A fixed set of options the user picks from.

{
  "type": "select",
  "options": [
    { "id": "opt_draft",    "label": "Draft" },
    { "id": "opt_review",   "label": "Review" },
    { "id": "opt_approved", "label": "Approved" }
  ]
}

Field	Type	Default	Description
options	SelectOption[]	[]	The allowed options to choose from
multiple	boolean	false	Allow selecting more than one

Each SelectOption:

Field	Type	Required	Description
id	string	Yes	Stable identifier, unique within the property. Statements store this.
label	string	Yes	Display text, unique (case-insensitive, trimmed) within the property.

On write, a Statement value may be an option id, a label (case-insensitive, trimmed), or a { "id", "label" } object; a mismatched id/label is rejected. Reads and display resolve stored ids back to labels via the current Schema.

Relation (relation)

References to other Subjects.

Field	Type	Required	Default	Description
relation	string	Yes	-	The relation type name
targetSchema	string	Yes	-	Name of the Schema that target Subjects must follow
multiple	boolean	No	false	Allow multiple relations

{
  "type": "relation",
  "relation": "Has product",
  "targetSchema": "Product",
  "multiple": true
}

Boolean (boolean)

A true/false value. No type-specific fields; default may be true, false, or null (no default).

{
  "type": "boolean",
  "default": false
}

Date (date)

A calendar date, stored as a strict ISO 8601 YYYY-MM-DD string (no time or timezone; see invalid-date). minimum, maximum, and any default use the same format.

Field	Type	Default	Description
minimum	string	null	Earliest allowed date
maximum	string	null	Latest allowed date

DateTime (dateTime)

A date and time, stored as a strict ISO 8601 / xsd:dateTime string with an explicit timezone offset or Z (e.g. 2025-06-15T14:30:00Z; see invalid-datetime). minimum, maximum, and any default use the same format.

Field	Type	Default	Description
minimum	string	null	Earliest allowed datetime
maximum	string	null	Latest allowed datetime

REST API

GET /neowiki/v0/schema/{schemaName} wraps this format as { "schema": ... }, or { "schema": null } when the Schema does not exist or you may not read it. There is no write endpoint; create or edit a Schema by editing its page in the Schema namespace.

Complete Example

A "Company" schema with various property types:

{
  "description": "A business entity",
  "propertyDefinitions": {
    "Founded at": {
      "type": "number",
      "description": "Year the company was founded"
    },
    "Websites": {
      "type": "url",
      "multiple": true
    },
    "Main product": {
      "type": "relation",
      "relation": "Has main product",
      "targetSchema": "Product"
    },
    "Products": {
      "type": "relation",
      "relation": "Has product",
      "targetSchema": "Product",
      "multiple": true
    },
    "Status": {
      "type": "select",
      "options": [
        { "id": "opt_active",    "label": "Active" },
        { "id": "opt_inactive",  "label": "Inactive" },
        { "id": "opt_acquired",  "label": "Acquired" },
        { "id": "opt_dissolved", "label": "Dissolved" }
      ],
      "required": true
    },
    "World domination progress": {
      "type": "number",
      "minimum": 0,
      "maximum": 100,
      "default": 0
    }
  }
}

Related Documentation

• Subject Format — format for the Subject data that follows Schemas.