Institute of Information Science - University of Miskolc

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==== JSON Schema Overview and Examples ====

**JSON Schema** is a tool to define and validate the structure of JSON data. It ensures that the data adheres to specific types, structures, and constraints, making it useful for APIs and data validation.

=== Basic JSON Schema Example ===
This schema defines a "Person" object with properties `name`, `age`, and `email`.

<sxh json>
{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Person",
  "type": "object",
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "integer", "minimum": 0 },
    "email": { "type": "string", "format": "email" }
  },
  "required": ["name", "email"]
}
</sxh>

**Explanation**:

  * ''name'' and ''email'' are required.
  * ''age'' is optional but must be a non-negative integer if provided.
  * ''email'' should be a valid email format.

==== Valid Example for this Schema: ====
<sxh json>
{
  "name": "John Doe",
  "age": 28,
  "email": "john@example.com"
}
</sxh>

=== Arrays in JSON Schema ===
You can validate arrays by specifying the type of items and enforcing constraints like ''minItems'' or ''uniqueItems''.

**Array Schema Example**
<sxh json>
{
  "type": "array",
  "items": { "type": "string" },
  "minItems": 1,
  "uniqueItems": true
}
</sxh>

This schema defines an array where:

  * Items must be strings.
  * The array must have at least one item.
  * All items must be unique.

**Valid JSON Array**:
<sxh json>
[
  "apple",
  "banana",
  "cherry"
]
</sxh>

=== Conditional Validation in JSON Schema ===
JSON Schema supports conditional logic using ''if'', ''then'', and ''else''.

**Schema for Conditional Validation**
<sxh json>
{
  "type": "object",
  "properties": {
    "isEmployed": { "type": "boolean" }
  },
  "if": {
    "properties": { "isEmployed": { "const": true } }
  },
  "then": {
    "properties": {
      "employer": { "type": "string" }
    },
    "required": ["employer"]
  },
  "else": {
    "properties": {
      "reasonUnemployed": { "type": "string" }
    },
    "required": ["reasonUnemployed"]
  }
}
</sxh>

**Explanation**:

  * If ''isEmployed'' is ''true'', ''employer'' must be provided.
  * If ''isEmployed'' is ''false'', ''reasonUnemployed'' must be provided.

**Valid Example (Employed)**:
<sxh json>
{
  "isEmployed": true,
  "employer": "TechCorp"
}
</sxh>

**Valid Example (Unemployed)**:
<sxh json>
{
  "isEmployed": false,
  "reasonUnemployed": "Student"
}
</sxh>

=== Summary ===
JSON Schema is versatile for defining the structure and validation rules for JSON data. It supports basic types, complex structures like arrays, and conditional logic, allowing developers to ensure data consistency and correctness. By using JSON Schema, you can make sure your data adheres to predefined formats, helping with integration and error prevention in APIs and applications.