@langchain/langgraph-checkpoint-postgres
v0.0.2
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LangGraph
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@langchain/langgraph-checkpoint-postgres
Implementation of a LangGraph.js CheckpointSaver that uses a Postgres DB.
Usage
import { PostgresSaver } from "@langchain/langgraph-checkpoint-postgres";
const writeConfig = {
configurable: {
thread_id: "1",
checkpoint_ns: ""
}
};
const readConfig = {
configurable: {
thread_id: "1"
}
};
const checkpointer = PostgresSaver.fromConnString("postgresql://...");
// You must call .setup() the first time you use the checkpointer:
await checkpointer.setup();
const 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.put(writeConfig, checkpoint, {}, {});
// load checkpoint
await checkpointer.get(readConfig);
// list checkpoints
for await (const checkpoint of checkpointer.list(readConfig)) {
console.log(checkpoint);
}
Testing
Spin up testing PostgreSQL
docker-compose up -d && docker-compose logs -f
Then use the following connection string to initialize your checkpointer:
const testCheckpointer = PostgresSaver.fromConnString(
"postgresql://user:password@localhost:5434/testdb"
);