对于 JSON 模式，引用定义使用“allOf”是否更好？

Question

在 JSON 模式中，当属性引用另一个定义的模式时，为了保留引用定义的类型，最好将引用定义包装在“allOf”中并在引用定义之外的该定义中指示属性类型吗？还是在引用的定义中指示属性类型而不使用“allOf”更好？

例如，在下面的第一个模式中，mainObject 和 objectA 的属性引用都包含在“allOf”中，并且在 mainObject 和 objectA 属性中具有“type”：“object”。而在模式版本 2 中，“mainObject”和“objectAInfo”定义指示“对象”的“类型”。

从我在测试中看到的情况来看，这两个都实现了相同的验证目标，所以我想知道是否有特别的理由使用模式版本 1 而不是模式版本 2？

架构版本 1：

{
  "info": {
    "title": "mainObject",
    "version": "0.0.1",
    "baseUri": "",
    "description": "An example object schema"
  },
  "properties": {
    "mainObject": {
      "type": "object",
      "allOf": [
        {
          "$ref": "#/definitions/mainObject"
        }
      ]
    }
  },
  "required": [],
  "definitions": {
    "mainObject": {
      "additionalProperties": false,
      "description": "The financials entity root.",
      "required": [],
      "properties": {
        "objectA": {
          "type": "object",
          "description": "Information on the liability accrued by the taxpayer",
          "allOf": [
            {
              "$ref": "#/definitions/objectAInfo"
            }
          ]
        }
      }
    },
    "objectAInfo": {
      "additionalProperties": false,
      "required": [],
      "properties": {
        "total1": {
          "type": "number",
          "description": "Overall liability accrued during the tax period. This number does not go down as the taxpayer pays off their liability. That is reflected in the periodBalance."
        },
        "total2": {
          "type": "number",
          "description": "Overall liability accrued during the tax period. This number does not go down as the taxpayer pays off their liability. That is reflected in the periodBalance."
        }
      }
    }
  },
  "$schema": "http://json-schema.org/draft-07/schema#",
  "lang": "zxx",
  "$id": "http://example.com/"
}

架构版本 2：

{
  "info": {
    "title": "mainObject",
    "version": "0.0.1",
    "baseUri": "",
    "description": "An example object schema"
  },
  "properties": {
    "mainObject": {
      "$ref": "#/definitions/mainObject"
    }
  },
  "required": [],
  "definitions": {
    "mainObject": {
      "type": "object",
      "additionalProperties": false,
      "description": "The financials entity root.",
      "required": [],
      "properties": {
        "objectA": {
          "$ref": "#/definitions/objectAInfo"
        }
      }
    },
    "objectAInfo": {
      "type": "object",
      "additionalProperties": false,
      "required": [],
      "properties": {
        "total1": {
          "type": "number",
          "description": "Overall liability accrued during the tax period. This number does not go down as the taxpayer pays off their liability. That is reflected in the periodBalance."
        },
        "total2": {
          "type": "number",
          "description": "Overall liability accrued during the tax period. This number does not go down as the taxpayer pays off their liability. That is reflected in the periodBalance."
        }
      }
    }
  },
  "$schema": "http://json-schema.org/draft-07/schema#",
  "lang": "zxx",
  "$id": "http://example.com/"
}

要验证的示例文档：

{
  "mainObject": {
    "objectA": {
      "total1": 0,
      "total2": 1
    }
  }
}

Answer 1

这取决于三件事：

1. 你用的是哪个草稿？草案 7 和更早的版本 require

   $ref

   本身，这意味着如果您有其他约束（例如，您的 Schema 1 中的

   type

   ），它们将被忽略。但是，在 2019-09 及以后的草案中，

   $ref

   可以有同级关键字（

   type

   也会被验证）。
2. 多个引用。如果您有多个引用，则必须将它们放在

   allOf

   中的单独子模式中。否则你会有重复的

   $ref

   键。
3. 可读性。即使对于现代模式，一些人仍然更喜欢单独使用引用，以帮助他们隔离不同的需求集。这是个人意见。

简短的回答：对于现代模式实现，这取决于你。请确保您使用

$schema

.

声明您使用的是哪个版本