一、簡介

我們先看下面的json數(shù)據(jù)

{ 
  "id": 1, 
  "name": "g2",　 
  "desc":"b2"
 }

假設, 我們要求id為long型, id、name非空。desc可空。如何衡量json數(shù)據(jù)是有效的呢？現(xiàn)在流行的json schema 是用來校驗json數(shù)據(jù)是否合法。

詳情請移至 https://spacetelescope.github.io/understanding-json-schema/

二、keyWords介紹

1、keyWords速記表

2、具體使用如下

type關鍵字
①、type = object, properties關鍵字是必需的。
②、type = array, items關鍵字是必需的。

porperties關鍵字

{
      type: "object";
      properties: {
        number: { type: "number" };
        name: { type: "string" };
      };
    }

additionalProperties關鍵字

"additionalProperties": false ：json串只能出現(xiàn)schema定義的屬性。
"additionalProperties": { "type": "string" } ：json串能出現(xiàn)不在schema定義范圍內(nèi)的屬性, 但屬性的類型必須為string

{
      type: "object";
      properties: { number: { type: "number" }; name: { type: "string" } };
      additionalProperties: false;
}

required關鍵字
"required": ["name"] ： json串必須出現(xiàn)name屬性

{
      type: "object";
      properties: { number: { type: "number" }; name: { type: "string" } };
      additionalProperties: false;
      required: ["name"];
}

dependencies關鍵字

dependencies": {
    "number": ["name"]
} 

number的出現(xiàn)必須依賴在name的基礎上, 換而言之 , number出現(xiàn),則name必須出現(xiàn);name的出現(xiàn)與number并沒有毛關系

{
      type: "object";
      properties: { number: { type: "number" }; name: { type: "string" } };
      additionalProperties: false;
      required: ["name"];
      dependencies: { number: ["name"] };
}

patternProperties關鍵字

"patternProperties": {
   "^S_": { "type": "string" },
   "^I_": { "type": "integer" }
}

以s、I開頭的屬性必須是String類型

{
      type: "object";
      properties: { number: { type: "number" }; name: { type: "string" } };
      additionalProperties: false;
      required: ["name"];
      dependencies: { number: ["name"] };
      patternProperties: {
        "^S_": { type: "string" };
        "^I_": { type: "integer" };
      };
}

enum關鍵字

{
      type: "string";
      enum: ["red", "amber", "green"];
}

anyOf關鍵字
anyOf: 對所有屬性范疇生效。所有屬性字符串長度最大不能》5

{
  "anyOf": [
    { "type": "string", "maxLength": 5 },
    { "type": "number", "minimum": 0 }
  ]
}

allOf關鍵字
allOf ： type必須相同。不能即String、又number

{
      allOf: [{ type: "string" }, { maxLength: 5 }];
}

oneOf關鍵字

{
  "type": "number",
  "oneOf": [
    { "multipleOf": 5 },
    { "multipleOf": 3 }
  ]
}

**not關鍵字****

{
  "not": {
    "type": "string"
  }
}

$schema關鍵字

schema ： 聲明json片段是json schema模式, 并不是 普通json串, 同時也聲明了json schema版本

三、拓展

1、復用

{
  "type": "object",
  "properties": {
    "street_address": { "type": "string" },
    "city":           { "type": "string" },
    "state":          { "type": "string" }
  },
  "required": ["street_address", "city", "state"]
}

如果我們想復用上述的json串, 可以使用definitions關鍵字。json結構定義如下 ：

{
  "definitions": {
    "address": {
      "type": "object",
      "properties": {
        "street_address": { "type": "string" },
        "city":           { "type": "string" },
        "state":          { "type": "string" }
      },
      "required": ["street_address", "city", "state"]
    }
  }
}

如何引用 ？ 可以使用$ref關鍵字

{ "$ref": "#/definitions/address" }

或者
{ "$ref": "definitions.json#/address" }

例子如下 ：
schema定義

{
  "$schema": "http://json-schema.org/draft-04/schema#",
 
  "definitions": {
    "address": {
      "type": "object",
      "properties": {
        "street_address": { "type": "string" },
        "city":           { "type": "string" },
        "state":          { "type": "string" }
      },
      "required": ["street_address", "city", "state"]
    }
  },
 
  "type": "object",
 
  "properties": {
    "billing_address": { "$ref": "#/definitions/address" },
    "shipping_address": { "$ref": "#/definitions/address" }
  }
}

目標匹配json數(shù)據(jù)

{
  "shipping_address": {
    "street_address": "1600 Pennsylvania Avenue NW",
    "city": "Washington",
    "state": "DC"
  },
  "billing_address": {
    "street_address": "1st Street SE",
    "city": "Washington",
    "state": "DC"
  }
}

2、延伸屬性

json schema

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "definitions": {
    "address": {
      "type": "object",
      "properties": {
        "street_address": { "type": "string" },
        "city":           { "type": "string" },
        "state":          { "type": "string" }
      },
      "required": ["street_address", "city", "state"]
    }
  },
  "type": "object",
  "properties": {
    "billing_address": { "$ref": "#/definitions/address" },
    "shipping_address": {
      "allOf": [
        { "$ref": "#/definitions/address" },
        { "properties":
          { "type": { "enum": [ "residential", "business" ] } },
          "required": ["type"]
        }
      ]
    }
  }
}

可匹配json

{
  "shipping_address": {
    "street_address": "1600 Pennsylvania Avenue NW",
    "city": "Washington",
    "state": "DC",
    "type": "business"
  }
}