如何在python-jsonschema文档中设置本地文件引用? [英] How to set up local file references in python-jsonschema document?

问题描述

我有一组 jsonschema 兼容文档.某些文档包含对其他文档的引用(通过$ref属性).我不希望托管这些文档，以便可以通过HTTP URI访问它们.因此，所有参考文献都是相对的.所有文档都位于本地文件夹结构中.

如何使 python-jsonschema 能够正确使用我的本地文件系统加载参考文件?

---

例如，如果我有一个文件名为defs.json的文档，其中包含一些定义.然后，我尝试加载引用它的其他文档，例如:

{
  "allOf": [
    {"$ref":"defs.json#/definitions/basic_event"},
    {
      "type": "object",
      "properties": {
        "action": {
          "type": "string",
          "enum": ["page_load"]
        }
      },
      "required": ["action"]
    }
  ]
}

我收到错误RefResolutionError: <urlopen error [Errno 2] No such file or directory: '/defs.json'>

我在Linux机器上可能很重要.

---

(我将其写为Q& A是因为我很难弄清楚这一点，并且也有麻烦.)

解决方案

您必须为每个使用相对引用的模式构建自定义jsonschema.RefResolver，并确保您的解析器知道给定模式在文件系统上的位置.

例如...

import os
import json
from jsonschema import Draft4Validator, RefResolver # We prefer Draft7, but jsonschema 3.0 is still in alpha as of this writing 


abs_path_to_schema = '/path/to/schema-doc-foobar.json'
with open(abs_path_to_schema, 'r') as fp:
  schema = json.load(fp)

resolver = RefResolver(
  # The key part is here where we build a custom RefResolver 
  # and tell it where *this* schema lives in the filesystem
  # Note that `file:` is for unix systems
  schema_path='file:{}'.format(abs_path_to_schema),
  schema=schema
)
Draft4Validator.check_schema(schema) # Unnecessary but a good idea
validator = Draft4Validator(schema, resolver=resolver, format_checker=None)

# Then you can...
data_to_validate = `{...}`
validator.validate(data_to_validate)

I have a set of jsonschema compliant documents. Some documents contain references to other documents (via the $ref attribute). I do not wish to host these documents such that they are accessible at an HTTP URI. As such, all references are relative. All documents live in a local folder structure.

How can I make python-jsonschema understand to properly use my local file system to load referenced documents?

---

For instance, if I have a document with filename defs.json containing some definitions. And I try to load a different document which references it, like:

{
  "allOf": [
    {"$ref":"defs.json#/definitions/basic_event"},
    {
      "type": "object",
      "properties": {
        "action": {
          "type": "string",
          "enum": ["page_load"]
        }
      },
      "required": ["action"]
    }
  ]
}

I get an error RefResolutionError: <urlopen error [Errno 2] No such file or directory: '/defs.json'>

It may be important that I'm on a linux box.

---

(I'm writing this as a Q&A because I had a hard time figuring this out and observed other folks having trouble too.)

解决方案

You must build a custom jsonschema.RefResolver for each schema which uses a relative reference and ensure that your resolver knows where on the filesystem the given schema lives.

Such as...

import os
import json
from jsonschema import Draft4Validator, RefResolver # We prefer Draft7, but jsonschema 3.0 is still in alpha as of this writing 


abs_path_to_schema = '/path/to/schema-doc-foobar.json'
with open(abs_path_to_schema, 'r') as fp:
  schema = json.load(fp)

resolver = RefResolver(
  # The key part is here where we build a custom RefResolver 
  # and tell it where *this* schema lives in the filesystem
  # Note that `file:` is for unix systems
  schema_path='file:{}'.format(abs_path_to_schema),
  schema=schema
)
Draft4Validator.check_schema(schema) # Unnecessary but a good idea
validator = Draft4Validator(schema, resolver=resolver, format_checker=None)

# Then you can...
data_to_validate = `{...}`
validator.validate(data_to_validate)

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