JSON 架构：为什么 "constant" 的验证方式与单值 "enum" 不同？

Question

我有一个对象，它提供一种资产版本的审计日志。它的几个属性（versionSource.metadata 和 versionSource.files）是应该根据其中一个属性的值根据两个模式之一进行验证的对象。我开始在我的子模式中使用常量（在 oneOf 内，但那是说所有子模式都经过验证（因此打破了 oneOf，因为不止一个经过验证。将其更改为不过，单值枚举有效。

为什么验证不同？

这是原始架构：

{
   "$id": "https://example.com/schemas/asset-version.json",
   "title": "Audit log of asset versions",
   "$schema": "http://json-schema.org/draft-07/schema",

   "type": "object",
   "required": [
      "assetID",
      "version",
      "versionSource"
   ],

   "properties": {
      "assetID": {
         "type": "string"
      },
      "version": {
         "type": "integer",
         "minimum": 1
      },
      "versionSource": {
         "type": "object",
         "properties": {
            "metadata": {
               "type": "object",
               "oneOf": [
                  {
                     "properties": {
                        "sourceType": { "constant": "client" }
                     }
                  },
                  {
                     "$ref": "#/definitions/version-source-previous-version"
                  }
               ]
            },
            "files": {
               "type": "object",
               "oneOf": [
                  {
                     "properties": {
                        "sourceType": { "constant": "upload" },
                        "sourceID": {
                           "type": "string"
                        }
                     }
                  },
                  {
                     "$ref": "#/definitions/version-source-previous-version"
                  }
               ]
            }
         }
      }
   },

   "definitions": {
      "version-source-previous-version": {
         "properties": {
            "sourceType": { "constant": "previous-version" },
            "sourceID": {
               "type": "integer",
               "minimum": 1
            }
         }
      }
   }
}

这是一份示例文档：

{
   "assetID": "0150a186-068d-43e7-bb8b-0a389b572379",
   "version": 1,
   "versionSource": {
      "metadata": {
         "sourceType": "client"
      },
      "files": {
         "sourceType": "upload",
         "sourceID": "54ae67b0-3e42-464a-a93f-3143b0f078fc"
      }
   },
   "created": "2018-09-01T00:00:00.00Z",
   "lastModified": "2018-09-02T12:10:00.00Z",
   "deleted": "2018-09-02T12:10:00.00Z"
}

还有一个：

{
   "assetID": "0150a186-068d-43e7-bb8b-0a389b572379",
   "version": 2,
   "versionSource": {
      "metadata": {
         "sourceType": "previous-version",
         "sourceID": 1
      },
      "files": {
         "sourceType": "previous-version",
         "sourceID": 1
      }
   },
   "created": "2018-09-01T00:00:00.00Z",
   "lastModified": "2018-09-02T12:10:00.00Z",
   "deleted": "2018-09-02T12:10:00.00Z"
}

这是我得到的错误：

消息：JSON 对来自 'oneOf' 的多个模式有效。有效的架构索引：0、1。架构路径： https://example.com/schemas/asset-version.json#/properties/versionSource/properties/metadata/oneOf

由于 sourceType 在 oneOf 的两个模式中都是常量，我真的不确定我的对象如何对这两个模式有效。

不过，将架构更改为以下内容有效：

{
   "$id": "https://example.com/schemas/asset-version.json",
   "title": "Audit log of asset versions",
   "$schema": "http://json-schema.org/draft-07/schema",

   "type": "object",
   "required": [
      "assetID",
      "version",
      "versionSource"
   ],

   "properties": {
      "assetID": {
         "type": "string"
      },
      "version": {
         "type": "integer",
         "minimum": 1
      },
      "versionSource": {
         "type": "object",
         "properties": {
            "metadata": {
               "type": "object",
               "oneOf": [
                  {
                     "properties": {
                        "sourceType": { "enum": [ "client" ] }
                     }
                  },
                  {
                     "$ref": "#/definitions/version-source-previous-version"
                  }
               ]
            },
            "files": {
               "type": "object",
               "oneOf": [
                  {
                     "properties": {
                        "sourceType": { "enum": [ "upload" ] },
                        "sourceID": {
                           "type": "string"
                        }
                     }
                  },
                  {
                     "$ref": "#/definitions/version-source-previous-version"
                  }
               ]
            }
         }
      }
   },

   "definitions": {
      "version-source-previous-version": {
         "properties": {
            "sourceType": { "enum": [ "previous-version" ] },
            "sourceID": {
               "type": "integer",
               "minimum": 1
            }
         }
      }
   }
}

我错过了什么？

Answer 1

嗯..没有什么是不正确的。由于您使用的是 draft-07，您可以尝试用 if/then/else 编写它，看看错误是否更有帮助。

但是...

您确定您使用的实现理解 draft-07 吗？如果它通过 draft-04 规则忽略 $schema 和运行它，它就不会理解 const。您应该为此检查您的工具文档。

Answer 2

这是我自己的错字……constant 应该是 const。 :facepalm:

Answer 3

根据草案 7

It should be noted that const is merely syntactic sugar for an enum with a single element, therefore the following are equivalent:

{ "const": "United States of America" }

{ "enum": [ "United States of America" ] }

有些人可能会发现提供 default 键在某些渲染表单解决方案中用于选择单个选项时很有用。

JSON 架构：为什么 "constant" 的验证方式与单值 "enum" 不同？

JSON schema: Why does "constant" not validate the same way as a single-valued "enum"?

json

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