JSONSchema

Document Ref JSONSchema，Validation

1.什么是 JSONSchema

JSON Schema 是一个允许您注释 和验证 JSON 文档的词汇表。

2.构建 JSONSchema

2.1 Example

{
"productId": 1,
"productName": "A green door",
"price": 12.50,
"tags": [ "home", "green" ]
}
​

如上 json 有一些问题，比如 productId 是什么,productName 是什么,如何验证里面的字段,price 可不可以为 0，上述 JSON 只是一份不完备的 JSON 文档

2.2 开始构建

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product in the catalog",
  "type": "object"
}
​

• $schema: 根据哪个 json 草案/标准进行编写的，还有版本信息
• $id: 定义了 Schema 的 URI，以及 Schema 内其他 URI 引用解析所依据的基本 URI
• title,description: 描述这个 JSON 文档的一些信息
• type: 这个字段是对 JSON 文档的第一个 约束，如上表明 json 文档为对象类型

type 还有如下几种类型

2.3 属性

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product from Acme's catalog",
  "type": "object",
  "properties": {
    "productId": {
      "description": "The unique identifier for a product",
      "type": "integer"
    }
  },
  "required": [ "productId" ]
}
​

• 使用 properties 定义属性，属性必须为一个对象，此对象的每个值都必须是有效的 JSON 模式。
• productId 是对象中的一个属性，拥有类型和描述两个字段
• required 的值必须是一个数组，如上表明 productId 是必须要验证的

2.4 更多限制

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product from Acme's catalog",
  "type": "object",
  "properties": {
    "productId": {
      "description": "The unique identifier for a product",
      "type": "integer"
    },
    "productName": {
      "description": "Name of the product",
      "type": "string"
    },
    "price": {
      "description": "The price of the product",
      "type": "number",
      "exclusiveMinimum": 0
    }
  },
  "required": [ "productId", "productName", "price" ]
}
​

• price 增加了 exclusiveMinimum，exclusiveMinimum 装饰的属性的值必须不是零。
• 如果你需要包含 0，那么可以使用 minimum 最小值来控制

2.5 验证 Numeric 类型

• multipleOf 其中之一
• maximum 最大限度
• exclusiveMaximum 不包含最大限度
• minimum 最小限度
• exclusiveMinimum 不包含最小限度

2.6 验证 String 类型

• maxLength 最大长度
• minLength 最小长度
• pattern 正则

2.7 验证 array 类型

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product from Acme's catalog",
  "type": "object",
  "properties": {
    "productId": {
      "description": "The unique identifier for a product",
      "type": "integer"
    },
    "productName": {
      "description": "Name of the product",
      "type": "string"
    },
    "price": {
      "description": "The price of the product",
      "type": "number",
      "exclusiveMinimum": 0
    },
    "tags": {
      "description": "Tags for the product",
      "type": "array",
      "items": {
        "type": "string"
      },
      "minItems": 1,
      "uniqueItems": true
    }
  },
  "required": [ "productId", "productName", "price" ]
}
​

• maxItems 最大数量
• minItems 最小数量
• uniqueItems 每个元素是不是都是唯一的
• maxContains
• minContains

2.8 验证 Objects 类型

{
  "$id": "https://example.com/address.schema.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "description": "An address similar to http://microformats.org/wiki/h-card",
  "type": "object",
  "properties": {
    "post-office-box": {
      "type": "string"
    },
    "extended-address": {
      "type": "string"
    },
    "street-address": {
      "type": "string"
    },
    "locality": {
      "type": "string"
    },
    "region": {
      "type": "string"
    },
    "postal-code": {
      "type": "string"
    },
    "country-name": {
      "type": "string"
    }
  },
  "required": [ "locality", "region", "country-name" ],
  "dependentRequired": {
    "post-office-box": [ "street-address" ],
    "extended-address": [ "street-address" ]
  }
}
​

• maxProperties 最大属性数量
• minProperties 最小属性数量
• required 必须有的属性列表
• dependentRequired 标记属性需要哪些属性依赖

2.9 嵌套数据结构

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product from Acme's catalog",
  "type": "object",
  "properties": {
    "productId": {
      "description": "The unique identifier for a product",
      "type": "integer"
    },
    "productName": {
      "description": "Name of the product",
      "type": "string"
    },
    "price": {
      "description": "The price of the product",
      "type": "number",
      "exclusiveMinimum": 0
    },
    "tags": {
      "description": "Tags for the product",
      "type": "array",
      "items": {
        "type": "string"
      },
      "minItems": 1,
      "uniqueItems": true
    },
    "dimensions": {
      "type": "object",
      "properties": {
        "length": {
          "type": "number"
        },
        "width": {
          "type": "number"
        },
        "height": {
          "type": "number"
        }
      },
      "required": [ "length", "width", "height" ]
    }
  },
  "required": [ "productId", "productName", "price" ]
}
​

• dimensions 作为 properties 其中还有一层 properties 和 required

2.10 引用外部定义 Schema

{
  "$id": "https://example.com/geographical-location.schema.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Longitude and Latitude",
  "description": "A geographical coordinate on a planet (most commonly Earth).",
  "required": [ "latitude", "longitude" ],
  "type": "object",
  "properties": {
    "latitude": {
      "type": "number",
      "minimum": -90,
      "maximum": 90
    },
    "longitude": {
      "type": "number",
      "minimum": -180,
      "maximum": 180
    }
  }
}
​

如上定义了一个 object

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/product.schema.json",
  "title": "Product",
  "description": "A product from Acme's catalog",
  "type": "object",
  "properties": {
    "productId": {
      "description": "The unique identifier for a product",
      "type": "integer"
    },
    "productName": {
      "description": "Name of the product",
      "type": "string"
    },
    "price": {
      "description": "The price of the product",
      "type": "number",
      "exclusiveMinimum": 0
    },
    "tags": {
      "description": "Tags for the product",
      "type": "array",
      "items": {
        "type": "string"
      },
      "minItems": 1,
      "uniqueItems": true
    },
    "dimensions": {
      "type": "object",
      "properties": {
        "length": {
          "type": "number"
        },
        "width": {
          "type": "number"
        },
        "height": {
          "type": "number"
        }
      },
      "required": [ "length", "width", "height" ]
    },
    "warehouseLocation": {
      "description": "Coordinates of the warehouse where the product is located.",
      "$ref": "https://example.com/geographical-location.schema.json"
    }
  },
  "required": [ "productId", "productName", "price" ]
}
​

• warehouseLocation 使用此属性名称来包含外部 JSONSchema