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Phoenix LoganandGitHub
aca67107c1
Replace hardcoded database saver class names with `cls` in `from_conn_string` factory methods to improve subclassing support ## Changes * Replaced direct class instantiations with `cls(conn)` in `from_conn_string` classmethods across all database implementations * Updated both synchronous and asynchronous variants for DuckDB, PostgreSQL, and SQLite savers ## Why This refactor makes the database saver classes more extensible by following Python's convention of using `cls` in class methods. This enables proper inheritance patterns where subclasses can reuse the factory methods without needing to override them. Previously, the hardcoded class names would always instantiate the parent class, even when called from a subclass. ## Testing The change is backward compatible and doesn't alter existing functionality. All existing tests should continue to pass as this is purely a structural refactoring that preserves the current behavior while improving extensibility. ## Notes This PR addresses follow up on comments from #2518 - AsyncPostgresSaver didn't need to be fixed but many of the other DB saver classes did.
LangGraph Checkpoint DuckDB
Implementation of LangGraph CheckpointSaver that uses DuckDB.
Usage
Important
When using DuckDB checkpointers for the first time, make sure to call
.setup()method on them to create required tables. See example below.
from langgraph.checkpoint.duckdb import DuckDBSaver
write_config = {"configurable": {"thread_id": "1", "checkpoint_ns": ""}}
read_config = {"configurable": {"thread_id": "1"}}
with DuckDBSaver.from_conn_string(":memory:") as checkpointer:
# call .setup() the first time you're using the checkpointer
checkpointer.setup()
checkpoint = {
"v": 1,
"ts": "2024-07-31T20:14:19.804150+00:00",
"id": "1ef4f797-8335-6428-8001-8a1503f9b875",
"channel_values": {
"my_key": "meow",
"node": "node"
},
"channel_versions": {
"__start__": 2,
"my_key": 3,
"start:node": 3,
"node": 3
},
"versions_seen": {
"__input__": {},
"__start__": {
"__start__": 1
},
"node": {
"start:node": 2
}
},
"pending_sends": [],
}
# store checkpoint
checkpointer.put(write_config, checkpoint, {}, {})
# load checkpoint
checkpointer.get(read_config)
# list checkpoints
list(checkpointer.list(read_config))
Async
from langgraph.checkpoint.duckdb.aio import AsyncDuckDBSaver
async with AsyncDuckDBSaver.from_conn_string(":memory:") as checkpointer:
checkpoint = {
"v": 1,
"ts": "2024-07-31T20:14:19.804150+00:00",
"id": "1ef4f797-8335-6428-8001-8a1503f9b875",
"channel_values": {
"my_key": "meow",
"node": "node"
},
"channel_versions": {
"__start__": 2,
"my_key": 3,
"start:node": 3,
"node": 3
},
"versions_seen": {
"__input__": {},
"__start__": {
"__start__": 1
},
"node": {
"start:node": 2
}
},
"pending_sends": [],
}
# store checkpoint
await checkpointer.aput(write_config, checkpoint, {}, {})
# load checkpoint
await checkpointer.aget(read_config)
# list checkpoints
[c async for c in checkpointer.alist(read_config)]