Validate JSON data with schemas, types, required fields, formats, composition, and API contracts.
Lessons
Use schemas to document and validate request and response payloads.
JSON Schema for APIs is easiest to learn by reading the example, changing it, and observing the result.
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"$id": "https://example.com/schemas/lesson.json",
"title": "Lesson",
"type": "object",
"required": ["slug", "title"],
"properties": {
"slug": { "type": "string", "pattern": "^[a-z0-9-]+$" },
"title": { "type": "string", "minLength": 3, "maxLength": 80 },
"minutes": { "type": "integer", "minimum": 1 },
"level": { "type": "string", "enum": ["beginner", "advanced"] },
"tags": { "type": "array", "items": { "type": "string" }, "uniqueItems": true }
},
"additionalProperties": false
}Practice the JSON Schema for APIs example in a small scratch file, then explain what changed and why.