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How to load JSON

JSON (JavaScript Object Notation) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays (or other serializable values).

JSON Lines is a file format where each line is a valid JSON value.

LangChain implements a JSONLoader to convert JSON and JSONL data into LangChain Document objects. It uses a specified jq schema to parse the JSON files, allowing for the extraction of specific fields into the content and metadata of the LangChain Document.

It uses the jq python package. Check out this manual for a detailed documentation of the jq syntax.

Here we will demonstrate:

  • How to load JSON and JSONL data into the content of a LangChain Document;
  • How to load JSON and JSONL data into metadata associated with a Document.
#!pip install jq
from langchain_community.document_loaders import JSONLoader
API Reference:JSONLoader
import json
from pathlib import Path
from pprint import pprint


file_path='./example_data/facebook_chat.json'
data = json.loads(Path(file_path).read_text())
pprint(data)
    {'image': {'creation_timestamp': 1675549016, 'uri': 'image_of_the_chat.jpg'},
     'is_still_participant': True,
     'joinable_mode': {'link': '', 'mode': 1},
     'magic_words': [],
     'messages': [{'content': 'Bye!',
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675597571851},
                  {'content': 'Oh no worries! Bye',
                   'sender_name': 'User 1',
                   'timestamp_ms': 1675597435669},
                  {'content': 'No Im sorry it was my mistake, the blue one is not '
                              'for sale',
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675596277579},
                  {'content': 'I thought you were selling the blue one!',
                   'sender_name': 'User 1',
                   'timestamp_ms': 1675595140251},
                  {'content': 'Im not interested in this bag. Im interested in the '
                              'blue one!',
                   'sender_name': 'User 1',
                   'timestamp_ms': 1675595109305},
                  {'content': 'Here is $129',
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675595068468},
                  {'photos': [{'creation_timestamp': 1675595059,
                               'uri': 'url_of_some_picture.jpg'}],
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675595060730},
                  {'content': 'Online is at least $100',
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675595045152},
                  {'content': 'How much do you want?',
                   'sender_name': 'User 1',
                   'timestamp_ms': 1675594799696},
                  {'content': 'Goodmorning! $50 is too low.',
                   'sender_name': 'User 2',
                   'timestamp_ms': 1675577876645},
                  {'content': 'Hi! Im interested in your bag. Im offering $50. Let '
                              'me know if you are interested. Thanks!',
                   'sender_name': 'User 1',
                   'timestamp_ms': 1675549022673}],
     'participants': [{'name': 'User 1'}, {'name': 'User 2'}],
     'thread_path': 'inbox/User 1 and User 2 chat',
     'title': 'User 1 and User 2 chat'}

Using JSONLoader​

Suppose we are interested in extracting the values under the content field within the messages key of the JSON data. This can easily be done through the JSONLoader as shown below.

JSON file​

loader = JSONLoader(
    file_path='./example_data/facebook_chat.json',
    jq_schema='.messages[].content',
    text_content=False)

data = loader.load()
pprint(data)
    [Document(page_content='Bye!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 1}),
     Document(page_content='Oh no worries! Bye', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 2}),
     Document(page_content='No Im sorry it was my mistake, the blue one is not for sale', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 3}),
     Document(page_content='I thought you were selling the blue one!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 4}),
     Document(page_content='Im not interested in this bag. Im interested in the blue one!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 5}),
     Document(page_content='Here is $129', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 6}),
     Document(page_content='', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 7}),
     Document(page_content='Online is at least $100', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 8}),
     Document(page_content='How much do you want?', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 9}),
     Document(page_content='Goodmorning! $50 is too low.', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 10}),
     Document(page_content='Hi! Im interested in your bag. Im offering $50. Let me know if you are interested. Thanks!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 11})]

JSON Lines file​

If you want to load documents from a JSON Lines file, you pass json_lines=True and specify jq_schema to extract page_content from a single JSON object.

file_path = './example_data/facebook_chat_messages.jsonl'
pprint(Path(file_path).read_text())
    ('{"sender_name": "User 2", "timestamp_ms": 1675597571851, "content": "Bye!"}\n'
     '{"sender_name": "User 1", "timestamp_ms": 1675597435669, "content": "Oh no '
     'worries! Bye"}\n'
     '{"sender_name": "User 2", "timestamp_ms": 1675596277579, "content": "No Im '
     'sorry it was my mistake, the blue one is not for sale"}\n')
loader = JSONLoader(
    file_path='./example_data/facebook_chat_messages.jsonl',
    jq_schema='.content',
    text_content=False,
    json_lines=True)

data = loader.load()
pprint(data)
    [Document(page_content='Bye!', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 1}),
     Document(page_content='Oh no worries! Bye', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 2}),
     Document(page_content='No Im sorry it was my mistake, the blue one is not for sale', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 3})]

Another option is to set jq_schema='.' and provide content_key:

loader = JSONLoader(
    file_path='./example_data/facebook_chat_messages.jsonl',
    jq_schema='.',
    content_key='sender_name',
    json_lines=True)

data = loader.load()
pprint(data)
    [Document(page_content='User 2', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 1}),
     Document(page_content='User 1', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 2}),
     Document(page_content='User 2', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat_messages.jsonl', 'seq_num': 3})]

JSON file with jq schema content_key​

To load documents from a JSON file using the content_key within the jq schema, set is_content_key_jq_parsable=True. Ensure that content_key is compatible and can be parsed using the jq schema.

file_path = './sample.json'
pprint(Path(file_path).read_text())
    {"data": [
        {"attributes": {
            "message": "message1",
            "tags": [
            "tag1"]},
        "id": "1"},
        {"attributes": {
            "message": "message2",
            "tags": [
            "tag2"]},
        "id": "2"}]}
loader = JSONLoader(
    file_path=file_path,
    jq_schema=".data[]",
    content_key=".attributes.message",
    is_content_key_jq_parsable=True,
)

data = loader.load()
pprint(data)
    [Document(page_content='message1', metadata={'source': '/path/to/sample.json', 'seq_num': 1}),
     Document(page_content='message2', metadata={'source': '/path/to/sample.json', 'seq_num': 2})]

Extracting metadata​

Generally, we want to include metadata available in the JSON file into the documents that we create from the content.

The following demonstrates how metadata can be extracted using the JSONLoader.

There are some key changes to be noted. In the previous example where we didn't collect the metadata, we managed to directly specify in the schema where the value for the page_content can be extracted from.

.messages[].content

In the current example, we have to tell the loader to iterate over the records in the messages field. The jq_schema then has to be:

.messages[]

This allows us to pass the records (dict) into the metadata_func that has to be implemented. The metadata_func is responsible for identifying which pieces of information in the record should be included in the metadata stored in the final Document object.

Additionally, we now have to explicitly specify in the loader, via the content_key argument, the key from the record where the value for the page_content needs to be extracted from.

# Define the metadata extraction function.
def metadata_func(record: dict, metadata: dict) -> dict:

    metadata["sender_name"] = record.get("sender_name")
    metadata["timestamp_ms"] = record.get("timestamp_ms")

    return metadata


loader = JSONLoader(
    file_path='./example_data/facebook_chat.json',
    jq_schema='.messages[]',
    content_key="content",
    metadata_func=metadata_func
)

data = loader.load()
pprint(data)
    [Document(page_content='Bye!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 1, 'sender_name': 'User 2', 'timestamp_ms': 1675597571851}),
     Document(page_content='Oh no worries! Bye', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 2, 'sender_name': 'User 1', 'timestamp_ms': 1675597435669}),
     Document(page_content='No Im sorry it was my mistake, the blue one is not for sale', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 3, 'sender_name': 'User 2', 'timestamp_ms': 1675596277579}),
     Document(page_content='I thought you were selling the blue one!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 4, 'sender_name': 'User 1', 'timestamp_ms': 1675595140251}),
     Document(page_content='Im not interested in this bag. Im interested in the blue one!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 5, 'sender_name': 'User 1', 'timestamp_ms': 1675595109305}),
     Document(page_content='Here is $129', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 6, 'sender_name': 'User 2', 'timestamp_ms': 1675595068468}),
     Document(page_content='', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 7, 'sender_name': 'User 2', 'timestamp_ms': 1675595060730}),
     Document(page_content='Online is at least $100', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 8, 'sender_name': 'User 2', 'timestamp_ms': 1675595045152}),
     Document(page_content='How much do you want?', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 9, 'sender_name': 'User 1', 'timestamp_ms': 1675594799696}),
     Document(page_content='Goodmorning! $50 is too low.', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 10, 'sender_name': 'User 2', 'timestamp_ms': 1675577876645}),
     Document(page_content='Hi! Im interested in your bag. Im offering $50. Let me know if you are interested. Thanks!', metadata={'source': '/Users/avsolatorio/WBG/langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 11, 'sender_name': 'User 1', 'timestamp_ms': 1675549022673})]

Now, you will see that the documents contain the metadata associated with the content we extracted.

The metadata_func​

As shown above, the metadata_func accepts the default metadata generated by the JSONLoader. This allows full control to the user with respect to how the metadata is formatted.

For example, the default metadata contains the source and the seq_num keys. However, it is possible that the JSON data contain these keys as well. The user can then exploit the metadata_func to rename the default keys and use the ones from the JSON data.

The example below shows how we can modify the source to only contain information of the file source relative to the langchain directory.

# Define the metadata extraction function.
def metadata_func(record: dict, metadata: dict) -> dict:

    metadata["sender_name"] = record.get("sender_name")
    metadata["timestamp_ms"] = record.get("timestamp_ms")

    if "source" in metadata:
        source = metadata["source"].split("/")
        source = source[source.index("langchain"):]
        metadata["source"] = "/".join(source)

    return metadata


loader = JSONLoader(
    file_path='./example_data/facebook_chat.json',
    jq_schema='.messages[]',
    content_key="content",
    metadata_func=metadata_func
)

data = loader.load()
pprint(data)
    [Document(page_content='Bye!', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 1, 'sender_name': 'User 2', 'timestamp_ms': 1675597571851}),
     Document(page_content='Oh no worries! Bye', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 2, 'sender_name': 'User 1', 'timestamp_ms': 1675597435669}),
     Document(page_content='No Im sorry it was my mistake, the blue one is not for sale', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 3, 'sender_name': 'User 2', 'timestamp_ms': 1675596277579}),
     Document(page_content='I thought you were selling the blue one!', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 4, 'sender_name': 'User 1', 'timestamp_ms': 1675595140251}),
     Document(page_content='Im not interested in this bag. Im interested in the blue one!', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 5, 'sender_name': 'User 1', 'timestamp_ms': 1675595109305}),
     Document(page_content='Here is $129', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 6, 'sender_name': 'User 2', 'timestamp_ms': 1675595068468}),
     Document(page_content='', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 7, 'sender_name': 'User 2', 'timestamp_ms': 1675595060730}),
     Document(page_content='Online is at least $100', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 8, 'sender_name': 'User 2', 'timestamp_ms': 1675595045152}),
     Document(page_content='How much do you want?', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 9, 'sender_name': 'User 1', 'timestamp_ms': 1675594799696}),
     Document(page_content='Goodmorning! $50 is too low.', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 10, 'sender_name': 'User 2', 'timestamp_ms': 1675577876645}),
     Document(page_content='Hi! Im interested in your bag. Im offering $50. Let me know if you are interested. Thanks!', metadata={'source': 'langchain/docs/modules/indexes/document_loaders/examples/example_data/facebook_chat.json', 'seq_num': 11, 'sender_name': 'User 1', 'timestamp_ms': 1675549022673})]

Common JSON structures with jq schema​

The list below provides a reference to the possible jq_schema the user can use to extract content from the JSON data depending on the structure.

JSON        -> [{"text": ...}, {"text": ...}, {"text": ...}]
jq_schema   -> ".[].text"

JSON        -> {"key": [{"text": ...}, {"text": ...}, {"text": ...}]}
jq_schema   -> ".key[].text"

JSON        -> ["...", "...", "..."]
jq_schema   -> ".[]"

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