{"record":{"id":"9ae0841e92c607d7","repo":"mem0ai/mem0","slug":"method-get-not-reliably-supported-by-langchainve","errorCode":null,"errorMessage":"Method 'get' not reliably supported by LangchainVectorStore wrapper.","messagePattern":"Method 'get' not reliably supported by LangchainVectorStore wrapper\\.","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"mem0-ts/src/oss/src/vector_stores/langchain.ts","lineNumber":145,"sourceCode":"      // Do not pass lcFilter here\n    );\n\n    // Map Langchain results [Document, score] back to mem0 VectorStoreResult\n    return results.map(([doc, score]) => ({\n      id: doc.metadata._mem0_id || \"unknown_id\",\n      payload: doc.metadata,\n      score: score,\n    }));\n  }\n\n  // --- Methods with No Direct Langchain Equivalent (Throwing Errors) ---\n\n  async get(vectorId: string): Promise<VectorStoreResult | null> {\n    // Most Langchain stores lack a direct getById. Simulation is inefficient.\n    console.error(\n      `LangchainVectorStore: The 'get' method is not directly supported by most Langchain VectorStores.`,\n    );\n    throw new Error(\n      \"Method 'get' not reliably supported by LangchainVectorStore wrapper.\",\n    );\n    // Potential (inefficient) simulation:\n    // Perform a search with a filter like { _mem0_id: vectorId }, limit 1.\n    // This requires the underlying store to support filtering on _mem0_id.\n  }\n\n  async update(\n    vectorId: string,\n    vector: number[],\n    payload: Record<string, any>,\n  ): Promise<void> {\n    // Updates often require delete + add in Langchain.\n    console.error(\n      `LangchainVectorStore: The 'update' method is not directly supported. Use delete followed by insert.`,\n    );\n    throw new Error(\n      \"Method 'update' not supported by LangchainVectorStore wrapper.\",","sourceCodeStart":127,"sourceCodeEnd":163,"githubUrl":"https://github.com/mem0ai/mem0/blob/001c235229be8795e3834520467bd0d661ed8f34/mem0-ts/src/oss/src/vector_stores/langchain.ts#L127-L163","documentation":"get(vectorId) is deliberately unimplemented in the Langchain adapter: the generic Langchain VectorStore interface has no standard get-by-id method, and simulating it via a filtered search is unreliable and inefficient. The adapter fails fast instead of returning wrong data. Note this is a hard throw, despite the dead code after it suggesting a simulation.","triggerScenarios":"Any code path that triggers VectorStore.get() — e.g. Memory.update() flows or custom code calling store.get(id) directly — while using the langchain provider.","commonSituations":"Switching a working setup from qdrant/chroma to langchain and hitting update flows that call get(); Memory APIs that internally fetch a single memory by id.","solutions":["Replace get() with a filtered search: store.search(anyVector, k, { memory_id: vectorId }) and pick the exact match, if the underlying store supports metadata filtering in similaritySearchVectorWithScore (note the wrapper currently does not forward filters — you may need a custom adapter).","Track mem0 memory ids to document metadata (_mem0_id) yourself and query the underlying Langchain store directly.","Switch to a provider that supports get (qdrant, chroma, pgvector, etc.) if per-id access is essential."],"exampleFix":null,"handlingStrategy":"fallback","validationCode":"// Capability check before relying on get():\nconst supportsGet = (s: any) => typeof s.get === 'function' && s.constructor?.name !== 'LangchainVectorStore';\nif (!supportsGet(store)) {\n  // route through search-by-memory_id or avoid the code path that calls get()\n}","typeGuard":null,"tryCatchPattern":"try {\n  const v = await store.get(id);\n} catch (e) {\n  if (e instanceof Error && e.message.includes(\"Method 'get' not reliably supported\")) {\n    // fallback: filtered search on memory_id against the underlying store\n    const results = await store.search(anyKnownVectorOfThatMemory, 1);\n    return results.find((r) => r.id === id) ?? null;\n  }\n  throw e;\n}","preventionTips":["Avoid per-id Memory flows with the langchain provider.","Keep your own id-to-metadata registry so get() is never needed.","Choose a provider with native get() if per-id access is required."],"tags":["langchain","unsupported-operation","vector-store","typescript"],"backgroundTag":null,"analyzedSha":"001c235229be8795e3834520467bd0d661ed8f34","analyzedAt":"2026-08-15T01:55:42.685Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}