16782975494

Committed 06 Aug 2025 04:40PM UTC coverage: 91.927% (-0.004%) from 91.931%

Build # 16782975494

Build Type

Pull #9678

github

Committed by

web-flow

Commit Message

Merge 65a54bd0a into 4b9fb20ba

Pull Request Pull Request #9678: Chore/pep585 type hints

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haystack/components/validators/json_schema.py

# SPDX-FileCopyrightText: 2022-present deepset GmbH <info@deepset.ai>
#
# SPDX-License-Identifier: Apache-2.0

import json
from typing import Any, Optional

from jsonschema import ValidationError, validate

from haystack import component
from haystack.dataclasses import ChatMessage


def is_valid_json(s: str) -> bool:
    """
    Check if the provided string is a valid JSON.

    :param s: The string to be checked.
    :returns: `True` if the string is a valid JSON; otherwise, `False`.
    """
    try:
        json.loads(s)
    except ValueError:
        return False
    return True


@component
class JsonSchemaValidator:
    """
    Validates JSON content of `ChatMessage` against a specified [JSON Schema](https://json-schema.org/).

    If JSON content of a message conforms to the provided schema, the message is passed along the "validated" output.
    If the JSON content does not conform to the schema, the message is passed along the "validation_error" output.
    In the latter case, the error message is constructed using the provided `error_template` or a default template.
    These error ChatMessages can be used by LLMs in Haystack 2.x recovery loops.

    Usage example:

    ```python
    from haystack import Pipeline
    from haystack.components.generators.chat import OpenAIChatGenerator
    from haystack.components.joiners import BranchJoiner
    from haystack.components.validators import JsonSchemaValidator
    from haystack import component
    from haystack.dataclasses import ChatMessage


    @component
    class MessageProducer:

        @component.output_types(messages=list[ChatMessage])
        def run(self, messages: list[ChatMessage]) -> dict:
            return {"messages": messages}


    p = Pipeline()
    p.add_component("llm", OpenAIChatGenerator(model="gpt-4-1106-preview",
                                               generation_kwargs={"response_format": {"type": "json_object"}}))
    p.add_component("schema_validator", JsonSchemaValidator())
    p.add_component("joiner_for_llm", BranchJoiner(list[ChatMessage]))
    p.add_component("message_producer", MessageProducer())

    p.connect("message_producer.messages", "joiner_for_llm")
    p.connect("joiner_for_llm", "llm")
    p.connect("llm.replies", "schema_validator.messages")
    p.connect("schema_validator.validation_error", "joiner_for_llm")

    result = p.run(data={
        "message_producer": {
            "messages":[ChatMessage.from_user("Generate JSON for person with name 'John' and age 30")]},
            "schema_validator": {
                "json_schema": {
                    "type": "object",
                    "properties": {"name": {"type": "string"},
                    "age": {"type": "integer"}
                }
            }
        }
    })
    print(result)
    >> {'schema_validator': {'validated': [ChatMessage(_role=<ChatRole.ASSISTANT: 'assistant'>,
    _content=[TextContent(text="\\n{\\n  "name": "John",\\n  "age": 30\\n}")],
    _name=None, _meta={'model': 'gpt-4-1106-preview', 'index': 0,
    'finish_reason': 'stop', 'usage': {'completion_tokens': 17, 'prompt_tokens': 20, 'total_tokens': 37}})]}}
    ```
    """

    # Default error description template
    default_error_template = (
        "The following generated JSON does not conform to the provided schema.\n"
        "Generated JSON: {failing_json}\n"
        "Error details:\n- Message: {error_message}\n"
        "- Error Path in JSON: {error_path}\n"
        "- Schema Path: {error_schema_path}\n"
        "Please match the following schema:\n"
        "{json_schema}\n"
        "and provide the corrected JSON content ONLY. Please do not output anything else than the raw corrected "
        "JSON string, this is the most important part of the task. Don't use any markdown and don't add any comment."
    )

    def __init__(self, json_schema: Optional[dict[str, Any]] = None, error_template: Optional[str] = None):
        """
        Initialize the JsonSchemaValidator component.

        :param json_schema: A dictionary representing the [JSON schema](https://json-schema.org/) against which
            the messages' content is validated.
        :param error_template: A custom template string for formatting the error message in case of validation failure.
        """
        self.json_schema = json_schema
        self.error_template = error_template

    @component.output_types(validated=list[ChatMessage], validation_error=list[ChatMessage])
    def run(
        self,
        messages: list[ChatMessage],
        json_schema: Optional[dict[str, Any]] = None,
        error_template: Optional[str] = None,
    ) -> dict[str, list[ChatMessage]]:
        """
        Validates the last of the provided messages against the specified json schema.

        If it does, the message is passed along the "validated" output. If it does not, the message is passed along
        the "validation_error" output.

        :param messages: A list of ChatMessage instances to be validated. The last message in this list is the one
            that is validated.
        :param json_schema: A dictionary representing the [JSON schema](https://json-schema.org/)
            against which the messages' content is validated. If not provided, the schema from the component init
            is used.
        :param error_template: A custom template string for formatting the error message in case of validation. If not
            provided, the `error_template` from the component init is used.
        :return:  A dictionary with the following keys:
            - "validated": A list of messages if the last message is valid.
            - "validation_error": A list of messages if the last message is invalid.
        :raises ValueError: If no JSON schema is provided or if the message content is not a dictionary or a list of
            dictionaries.
        """
        last_message = messages[-1]
        if last_message.text is None:
            raise ValueError(f"The provided ChatMessage has no text. ChatMessage: {last_message}")
        if not is_valid_json(last_message.text):
            return {
                "validation_error": [
                    ChatMessage.from_user(
                        f"The message '{last_message.text}' is not a valid JSON object. "
                        f"Please provide only a valid JSON object in string format."
                        f"Don't use any markdown and don't add any comment."
                    )
                ]
            }

        last_message_content = json.loads(last_message.text)
        json_schema = json_schema or self.json_schema
        error_template = error_template or self.error_template or self.default_error_template

        if not json_schema:
            raise ValueError("Provide a JSON schema for validation either in the run method or in the component init.")
        # fc payload is json object but subtree `parameters` is string - we need to convert to json object
        # we need complete json to validate it against schema
        last_message_json = self._recursive_json_to_object(last_message_content)
        using_openai_schema: bool = self._is_openai_function_calling_schema(json_schema)
        if using_openai_schema:
            validation_schema = json_schema["parameters"]
        else:
            validation_schema = json_schema
        try:
            last_message_json = [last_message_json] if not isinstance(last_message_json, list) else last_message_json
            for content in last_message_json:
                if using_openai_schema:
                    validate(instance=content["function"]["arguments"], schema=validation_schema)
                else:
                    validate(instance=content, schema=validation_schema)

            return {"validated": [last_message]}
        except ValidationError as e:
            error_path = " -> ".join(map(str, e.absolute_path)) if e.absolute_path else "N/A"
            error_schema_path = " -> ".join(map(str, e.absolute_schema_path)) if e.absolute_schema_path else "N/A"

            error_template = error_template or self.default_error_template

            recovery_prompt = self._construct_error_recovery_message(
                error_template, str(e), error_path, error_schema_path, validation_schema, failing_json=last_message.text
            )
            return {"validation_error": [ChatMessage.from_user(recovery_prompt)]}

    def _construct_error_recovery_message(  # pylint: disable=too-many-positional-arguments
        self,
        error_template: str,
        error_message: str,
        error_path: str,
        error_schema_path: str,
        json_schema: dict[str, Any],
        failing_json: str,
    ) -> str:
        """
        Constructs an error recovery message using a specified template or the default one if none is provided.

        :param error_template: A custom template string for formatting the error message in case of validation failure.
        :param error_message: The error message returned by the JSON schema validator.
        :param error_path: The path in the JSON content where the error occurred.
        :param error_schema_path: The path in the JSON schema where the error occurred.
        :param json_schema: The JSON schema against which the content is validated.
        :param failing_json: The generated invalid JSON string.
        """
        error_template = error_template or self.default_error_template

        return error_template.format(
            error_message=error_message,
            error_path=error_path,
            error_schema_path=error_schema_path,
            json_schema=json_schema,
            failing_json=failing_json,
        )

    def _is_openai_function_calling_schema(self, json_schema: dict[str, Any]) -> bool:
        """
        Checks if the provided schema is a valid OpenAI function calling schema.

        :param json_schema: The JSON schema to check
        :return: `True` if the schema is a valid OpenAI function calling schema; otherwise, `False`.
        """
        return all(key in json_schema for key in ["name", "description", "parameters"])

    def _recursive_json_to_object(self, data: Any) -> Any:
        """
        Convert any string values that are valid JSON objects into dictionary objects.

        Returns a new data structure.

        :param data: The data structure to be traversed.
        :return: A new data structure with JSON strings converted to dictionary objects.
        """
        if isinstance(data, list):
            return [self._recursive_json_to_object(item) for item in data]

        if isinstance(data, dict):
            new_dict = {}
            for key, value in data.items():
                if isinstance(value, str):
                    try:
                        json_value = json.loads(value)
                        if isinstance(json_value, (dict, list)):
                            new_dict[key] = self._recursive_json_to_object(json_value)
                        else:
                            new_dict[key] = value  # Preserve the original string value
                    except json.JSONDecodeError:
                        new_dict[key] = value
                elif isinstance(value, dict):
                    new_dict[key] = self._recursive_json_to_object(value)
                else:
                    new_dict[key] = value
            return new_dict

        # If it's neither a list nor a dictionary, return the value directly
        raise ValueError("Input must be a dictionary or a list of dictionaries.")

1	# SPDX-FileCopyrightText: 2022-present deepset GmbH <info@deepset.ai>
2	#
3	# SPDX-License-Identifier: Apache-2.0
4
5	import json	1✔
6	from typing import Any, Optional	1✔
7
8	from jsonschema import ValidationError, validate	1✔
9
10	from haystack import component	1✔
11	from haystack.dataclasses import ChatMessage	1✔
12
13
14	def is_valid_json(s: str) -> bool:	1✔
15	"""
16	Check if the provided string is a valid JSON.
17
18	:param s: The string to be checked.
19	:returns: `True` if the string is a valid JSON; otherwise, `False`.
20	"""
21	try:	1✔
22	json.loads(s)	1✔
23	except ValueError:	×
24	return False	×
25	return True	1✔
26
27
28	@component	1✔
29	class JsonSchemaValidator:	1✔
30	"""
31	Validates JSON content of `ChatMessage` against a specified [JSON Schema](https://json-schema.org/).
32
33	If JSON content of a message conforms to the provided schema, the message is passed along the "validated" output.
34	If the JSON content does not conform to the schema, the message is passed along the "validation_error" output.
35	In the latter case, the error message is constructed using the provided `error_template` or a default template.
36	These error ChatMessages can be used by LLMs in Haystack 2.x recovery loops.
37
38	Usage example:
39
40	```python
41	from haystack import Pipeline
42	from haystack.components.generators.chat import OpenAIChatGenerator
43	from haystack.components.joiners import BranchJoiner
44	from haystack.components.validators import JsonSchemaValidator
45	from haystack import component
46	from haystack.dataclasses import ChatMessage
47
48
49	@component
50	class MessageProducer:
51
52	@component.output_types(messages=list[ChatMessage])
53	def run(self, messages: list[ChatMessage]) -> dict:
54	return {"messages": messages}
55
56
57	p = Pipeline()
58	p.add_component("llm", OpenAIChatGenerator(model="gpt-4-1106-preview",
59	generation_kwargs={"response_format": {"type": "json_object"}}))
60	p.add_component("schema_validator", JsonSchemaValidator())
61	p.add_component("joiner_for_llm", BranchJoiner(list[ChatMessage]))
62	p.add_component("message_producer", MessageProducer())
63
64	p.connect("message_producer.messages", "joiner_for_llm")
65	p.connect("joiner_for_llm", "llm")
66	p.connect("llm.replies", "schema_validator.messages")
67	p.connect("schema_validator.validation_error", "joiner_for_llm")
68
69	result = p.run(data={
70	"message_producer": {
71	"messages":[ChatMessage.from_user("Generate JSON for person with name 'John' and age 30")]},
72	"schema_validator": {
73	"json_schema": {
74	"type": "object",
75	"properties": {"name": {"type": "string"},
76	"age": {"type": "integer"}
77	}
78	}
79	}
80	})
81	print(result)
82	>> {'schema_validator': {'validated': [ChatMessage(_role=<ChatRole.ASSISTANT: 'assistant'>,
83	_content=[TextContent(text="\\n{\\n "name": "John",\\n "age": 30\\n}")],
84	_name=None, _meta={'model': 'gpt-4-1106-preview', 'index': 0,
85	'finish_reason': 'stop', 'usage': {'completion_tokens': 17, 'prompt_tokens': 20, 'total_tokens': 37}})]}}
86	```
87	"""
88
89	# Default error description template
90	default_error_template = (	1✔
91	"The following generated JSON does not conform to the provided schema.\n"
92	"Generated JSON: {failing_json}\n"
93	"Error details:\n- Message: {error_message}\n"
94	"- Error Path in JSON: {error_path}\n"
95	"- Schema Path: {error_schema_path}\n"
96	"Please match the following schema:\n"
97	"{json_schema}\n"
98	"and provide the corrected JSON content ONLY. Please do not output anything else than the raw corrected "
99	"JSON string, this is the most important part of the task. Don't use any markdown and don't add any comment."
100	)
101
102	def __init__(self, json_schema: Optional[dict[str, Any]] = None, error_template: Optional[str] = None):	1✔
103	"""
104	Initialize the JsonSchemaValidator component.
105
106	:param json_schema: A dictionary representing the [JSON schema](https://json-schema.org/) against which
107	the messages' content is validated.
108	:param error_template: A custom template string for formatting the error message in case of validation failure.
109	"""
110	self.json_schema = json_schema	1✔
111	self.error_template = error_template	1✔
112
113	@component.output_types(validated=list[ChatMessage], validation_error=list[ChatMessage])	1✔
114	def run(	1✔
115	self,
116	messages: list[ChatMessage],
117	json_schema: Optional[dict[str, Any]] = None,
118	error_template: Optional[str] = None,
119	) -> dict[str, list[ChatMessage]]:
120	"""
121	Validates the last of the provided messages against the specified json schema.
122
123	If it does, the message is passed along the "validated" output. If it does not, the message is passed along
124	the "validation_error" output.
125
126	:param messages: A list of ChatMessage instances to be validated. The last message in this list is the one
127	that is validated.
128	:param json_schema: A dictionary representing the [JSON schema](https://json-schema.org/)
129	against which the messages' content is validated. If not provided, the schema from the component init
130	is used.
131	:param error_template: A custom template string for formatting the error message in case of validation. If not
132	provided, the `error_template` from the component init is used.
133	:return: A dictionary with the following keys:
134	- "validated": A list of messages if the last message is valid.
135	- "validation_error": A list of messages if the last message is invalid.
136	:raises ValueError: If no JSON schema is provided or if the message content is not a dictionary or a list of
137	dictionaries.
138	"""
139	last_message = messages[-1]	1✔
140	if last_message.text is None:	1✔
141	raise ValueError(f"The provided ChatMessage has no text. ChatMessage: {last_message}")	×
142	if not is_valid_json(last_message.text):	1✔
143	return {	×
144	"validation_error": [
145	ChatMessage.from_user(
146	f"The message '{last_message.text}' is not a valid JSON object. "
147	f"Please provide only a valid JSON object in string format."
148	f"Don't use any markdown and don't add any comment."
149	)
150	]
151	}
152
153	last_message_content = json.loads(last_message.text)	1✔
154	json_schema = json_schema or self.json_schema	1✔
155	error_template = error_template or self.error_template or self.default_error_template	1✔
156
157	if not json_schema:	1✔
158	raise ValueError("Provide a JSON schema for validation either in the run method or in the component init.")	×
159	# fc payload is json object but subtree `parameters` is string - we need to convert to json object
160	# we need complete json to validate it against schema
161	last_message_json = self._recursive_json_to_object(last_message_content)	1✔
162	using_openai_schema: bool = self._is_openai_function_calling_schema(json_schema)	1✔
163	if using_openai_schema:	1✔
164	validation_schema = json_schema["parameters"]	1✔
165	else:
166	validation_schema = json_schema	1✔
167	try:	1✔
168	last_message_json = [last_message_json] if not isinstance(last_message_json, list) else last_message_json	1✔
169	for content in last_message_json:	1✔
170	if using_openai_schema:	1✔
171	validate(instance=content["function"]["arguments"], schema=validation_schema)	1✔
172	else:
173	validate(instance=content, schema=validation_schema)	1✔
174
175	return {"validated": [last_message]}	1✔
176	except ValidationError as e:	1✔
177	error_path = " -> ".join(map(str, e.absolute_path)) if e.absolute_path else "N/A"	1✔
178	error_schema_path = " -> ".join(map(str, e.absolute_schema_path)) if e.absolute_schema_path else "N/A"	1✔
179
180	error_template = error_template or self.default_error_template	1✔
181
182	recovery_prompt = self._construct_error_recovery_message(	1✔
183	error_template, str(e), error_path, error_schema_path, validation_schema, failing_json=last_message.text
184	)
185	return {"validation_error": [ChatMessage.from_user(recovery_prompt)]}	1✔
186
187	def _construct_error_recovery_message( # pylint: disable=too-many-positional-arguments	1✔
188	self,
189	error_template: str,
190	error_message: str,
191	error_path: str,
192	error_schema_path: str,
193	json_schema: dict[str, Any],
194	failing_json: str,
195	) -> str:
196	"""
197	Constructs an error recovery message using a specified template or the default one if none is provided.
198
199	:param error_template: A custom template string for formatting the error message in case of validation failure.
200	:param error_message: The error message returned by the JSON schema validator.
201	:param error_path: The path in the JSON content where the error occurred.
202	:param error_schema_path: The path in the JSON schema where the error occurred.
203	:param json_schema: The JSON schema against which the content is validated.
204	:param failing_json: The generated invalid JSON string.
205	"""
206	error_template = error_template or self.default_error_template	1✔
207
208	return error_template.format(	1✔
209	error_message=error_message,
210	error_path=error_path,
211	error_schema_path=error_schema_path,
212	json_schema=json_schema,
213	failing_json=failing_json,
214	)
215
216	def _is_openai_function_calling_schema(self, json_schema: dict[str, Any]) -> bool:	1✔
217	"""
218	Checks if the provided schema is a valid OpenAI function calling schema.
219
220	:param json_schema: The JSON schema to check
221	:return: `True` if the schema is a valid OpenAI function calling schema; otherwise, `False`.
222	"""
223	return all(key in json_schema for key in ["name", "description", "parameters"])	1✔
224
225	def _recursive_json_to_object(self, data: Any) -> Any:	1✔
226	"""
227	Convert any string values that are valid JSON objects into dictionary objects.
228
229	Returns a new data structure.
230
231	:param data: The data structure to be traversed.
232	:return: A new data structure with JSON strings converted to dictionary objects.
233	"""
234	if isinstance(data, list):	1✔
235	return [self._recursive_json_to_object(item) for item in data]	1✔
236
237	if isinstance(data, dict):	1✔
238	new_dict = {}	1✔
239	for key, value in data.items():	1✔
240	if isinstance(value, str):	1✔
241	try:	1✔
242	json_value = json.loads(value)	1✔
243	if isinstance(json_value, (dict, list)):	1✔
244	new_dict[key] = self._recursive_json_to_object(json_value)	1✔
245	else:
246	new_dict[key] = value # Preserve the original string value	×
247	except json.JSONDecodeError:	1✔
248	new_dict[key] = value	1✔
249	elif isinstance(value, dict):	1✔
250	new_dict[key] = self._recursive_json_to_object(value)	1✔
251	else:
252	new_dict[key] = value	×
253	return new_dict	1✔
254
255	# If it's neither a list nor a dictionary, return the value directly
256	raise ValueError("Input must be a dictionary or a list of dictionaries.")	×

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