Schema Tools

Collection of tools to parse, query, map,… Json/Yaml schemas

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Features at a Glance

  • support for (loading of) Json and Yaml schemas with additional access to line and column information as an Abstract Syntax Tree (AST)

>>> from schema_tools import json
>>> j = json.loads('''{
...   "hello" : "world",
...   "count" : [
...     1,
...     2,
...     3
...   ]
... }''')
>>> j
ObjectNode(len=2, line=1, column=1)
>>> j()
{'hello': 'world', 'count': [1, 2, 3]}

>>> from schema_tools import yaml
>>> y = yaml.loads('''
... hello : world
... count :
... - 1
... - 2
... - 3
... ''')
>>> y
ObjectNode(len=2, line=1, column=1)
>>> y()
{'hello': 'world', 'count': [1, 2, 3]}

>>> for k, v in y:
...   print(k, v)
... 
hello ValueNode(value=world, line=2, column=9)
count ListNode(len=3, line=3, column=1)

>>> from schema_tools.utils import node_location
>>> l = node_location(j.count)
>>> l.line
3
>>> l.column
13
>>> node_location(y.count)
NodeLocation(3, 0)
>>> node_location(j["count"])
NodeLocation(3, 13)
>>> node_location(y["count"])
NodeLocation(3, 0)

  • a schema oriented object model

>>> from schema_tools.schema import loads
>>> json_src = '''
... {
...   "$schema": "http://json-schema.org/draft-07/schema#",
...   "$id": "test",
...   "title": "a title",
...   "description": "a description",
...   "version": "123",
...   "type": "object",
...   "properties" : {
...     "home" : {
...       "anyOf" : [
...         { "$ref" : "#/definitions/address" },
...         { "$ref" : "#/definitions/id"      }
...       ]
...     }
...   },
...   "definitions" : {
...     "id" : {
...       "type" : "string"
...     },
...     "address" : {
...       "type" : "object",
...       "properties" : {
...         "url": {
...           "type": "string",
...           "format": "uri-reference"
...         }
...       },
...       "additionalProperties" : false,
...       "required" : [
...         "url"
...       ]
...     } 
...   }
... }'''
>>> schema = loads(json_src)
>>> schema
ObjectSchema($schema=http://json-schema.org/draft-07/schema#, $id=test, title=a title, description=a description, version=123, type=object, properties=1, definitions=2, location=NodeLocation(line=2, column=1))
>>> schema.properties[0]
Property(name=home, definition=AnyOf(options=2, location=NodeLocation(line=10, column=14)), location=None)
>>> schema.properties[0].definition.options[1]
Reference(ref=#/definitions/id)
>>> schema.properties[0].definition.options[1].resolve()
StringSchema(type=string, location=NodeLocation(line=18, column=12))
>>> schema.properties[0].definition.options[1].resolve().parent.name
'id'

  • (re) generate dict/textual representation

>>> import json
>>> from schema_tools.schema import load
>>> schema = load("tests/schemas/json-schema-draft-07.json")
>>> d = schema.to_dict()
>>> s = json.dumps(d, indent=2, sort_keys=True)
>>> print(s[:150], "{}\n...\n{}".format(s[:147], s[-83:]))
{
  "$id": "http://json-schema.org/draft-07/schema#",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "default": true,
  "definitions": {
   {
  "$id": "http://json-schema.org/draft-07/schema#",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "default": true,
  "definitions": {
...
  "title": "Core schema meta-schema",
  "type": [
    "object",
    "boolean"
  ]
}

  • use property selectors - across schema boundaries ;-)

>>> from schema_tools.schema import load
>>> schema = load("tests/schemas/invoice.json")
>>> amount = schema.select("lines.price.amount")
>>> amount.parent.parent
ObjectSchema($schema=http://json-schema.org/draft-07/schema#, $id=file:tests/schemas/money.json, type=object, version=1, additionalProperties=False, required=['amount', 'currency'], properties=2, definitions=0, location=NodeLocation(line=1, column=1))

  • define mapping between schemas with mapping validation

>>> from schema_tools.schema import load
>>> source = load("tests/schemas/product.json").select("cost.amount")
>>> target = load("tests/schemas/invoice.json").select("lines.price.amount")
>>> from schema_tools.mapping import Mapping
>>> m = Mapping(source, target)
>>> m.is_valid
True
>>> target = load("tests/schemas/invoice.json").select("lines.price.currency")
>>> m = Mapping(source, target)
>>> m.is_valid
False
>>> False
False
>>> print(m.status)
source:IntegerSchema(type=integer, location=NodeLocation(line=7, column=15))
target:StringSchema(type=string, location=NodeLocation(line=10, column=17))
source type 'IntegerSchema' doesn't match target type 'StringSchema'