1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
class Chain(RunnableSerializable[dict[str, Any], dict[str, Any]], ABC):
"""Abstract base class for creating structured sequences of calls to components.
Chains should be used to encode a sequence of calls to components like
models, document retrievers, other chains, etc., and provide a simple interface
to this sequence.
The Chain interface makes it easy to create apps that are:
- Stateful: add Memory to any Chain to give it state,
- Observable: pass Callbacks to a Chain to execute additional functionality,
like logging, outside the main sequence of component calls,
- Composable: the Chain API is flexible enough that it is easy to combine
Chains with other components, including other Chains.
The main methods exposed by chains are:
- `__call__`: Chains are callable. The `__call__` method is the primary way to
execute a Chain. This takes inputs as a dictionary and returns a
dictionary output.
- `run`: A convenience method that takes inputs as args/kwargs and returns the
output as a string or object. This method can only be used for a subset of
chains and cannot return as rich of an output as `__call__`.
"""
memory: Optional[BaseMemory] = None
"""Optional memory object. Defaults to None.
Memory is a class that gets called at the start
and at the end of every chain. At the start, memory loads variables and passes
them along in the chain. At the end, it saves any returned variables.
There are many different types of memory - please see memory docs
for the full catalog."""
callbacks: Callbacks = Field(default=None, exclude=True)
"""Optional list of callback handlers (or callback manager). Defaults to None.
Callback handlers are called throughout the lifecycle of a call to a chain,
starting with on_chain_start, ending with on_chain_end or on_chain_error.
Each custom chain can optionally call additional callback methods, see Callback docs
for full details."""
verbose: bool = Field(default_factory=_get_verbosity)
"""Whether or not run in verbose mode. In verbose mode, some intermediate logs
will be printed to the console. Defaults to the global `verbose` value,
accessible via `langchain.globals.get_verbose()`."""
tags: Optional[list[str]] = None
"""Optional list of tags associated with the chain. Defaults to None.
These tags will be associated with each call to this chain,
and passed as arguments to the handlers defined in `callbacks`.
You can use these to eg identify a specific instance of a chain with its use case.
"""
metadata: Optional[dict[str, Any]] = None
"""Optional metadata associated with the chain. Defaults to None.
This metadata will be associated with each call to this chain,
and passed as arguments to the handlers defined in `callbacks`.
You can use these to eg identify a specific instance of a chain with its use case.
"""
callback_manager: Optional[BaseCallbackManager] = Field(default=None, exclude=True)
"""[DEPRECATED] Use `callbacks` instead."""
model_config = ConfigDict(
arbitrary_types_allowed=True,
)
|
