refactor: improve Ollama embedder, normalize model names, add error handling, update tests (#4403)

mem0-ts/src/oss/src/embeddings/ollama.ts

@@ -27,14 +27,18 @@ export class OllamaEmbedder implements Embedder {
     } catch (err) {
       logger.error(`Error ensuring model exists: ${err}`);
     }
-    // Ollama's Go server requires prompt to be a string. Coerce defensively
-    // since callers may pass values parsed from untrusted LLM JSON output.
-    const prompt = typeof text === "string" ? text : JSON.stringify(text);
-    const response = await this.ollama.embeddings({
+    // Coerce defensively since callers may pass values parsed from untrusted LLM JSON output.
+    const input = typeof text === "string" ? text : JSON.stringify(text);
+    const response = await this.ollama.embed({
       model: this.model,
-      prompt,
+      input,
     });
-    return response.embedding;
+    if (!response.embeddings || response.embeddings.length === 0) {
+      throw new Error(
+        `Ollama embed() returned no embeddings for model '${this.model}'`,
+      );
+    }
+    return response.embeddings[0];
   }
 
   async embedBatch(texts: string[]): Promise<number[][]> {
@@ -42,12 +46,21 @@ export class OllamaEmbedder implements Embedder {
     return response;
   }
 
+  private static normalizeModelName(name: string): string {
+    return name.includes(":") ? name : `${name}:latest`;
+  }
+
   private async ensureModelExists(): Promise<boolean> {
     if (this.initialized) {
       return true;
     }
     const local_models = await this.ollama.list();
-    if (!local_models.models.find((m: any) => m.name === this.model)) {
+    const target = OllamaEmbedder.normalizeModelName(this.model);
+    if (
+      !local_models.models.find(
+        (m: any) => OllamaEmbedder.normalizeModelName(m.name) === target,
+      )
+    ) {
       logger.info(`Pulling model ${this.model}...`);
       await this.ollama.pull({ model: this.model });
     }

mem0-ts/src/oss/tests/ollama-embedder.test.ts

@@ -0,0 +1,121 @@
+/// <reference types="jest" />
+/**
+ * Ollama Embedder — unit tests (mocked Ollama client).
+ */
+
+import { OllamaEmbedder } from "../src/embeddings/ollama";
+
+const mockEmbedding = [0.1, 0.2, 0.3, 0.4, 0.5];
+const mockEmbed = jest.fn().mockResolvedValue({
+  model: "nomic-embed-text:latest",
+  embeddings: [mockEmbedding],
+});
+const mockList = jest.fn().mockResolvedValue({
+  models: [{ name: "nomic-embed-text:latest" }],
+});
+const mockPull = jest.fn().mockResolvedValue({});
+
+jest.mock("ollama", () => ({
+  Ollama: jest.fn().mockImplementation(() => ({
+    embed: mockEmbed,
+    list: mockList,
+    pull: mockPull,
+  })),
+}));
+
+describe("OllamaEmbedder (unit)", () => {
+  beforeEach(() => {
+    mockEmbed.mockClear();
+    mockList.mockClear();
+    mockPull.mockClear();
+  });
+
+  it("embed() calls ollama.embed with model and input, returns first embedding", async () => {
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    const result = await embedder.embed("Sample text to embed.");
+
+    expect(mockEmbed).toHaveBeenCalledTimes(1);
+    expect(mockEmbed.mock.calls[0][0]).toEqual({
+      model: "nomic-embed-text:latest",
+      input: "Sample text to embed.",
+    });
+    expect(result).toEqual(mockEmbedding);
+  });
+
+  it("embed() coerces non-string input to JSON string", async () => {
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    // Force a non-string through the type boundary
+    await embedder.embed(42 as any);
+
+    expect(mockEmbed.mock.calls[0][0].input).toBe("42");
+  });
+
+  it("embedBatch() returns vectors for multiple inputs", async () => {
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    const result = await embedder.embedBatch(["text1", "text2"]);
+
+    expect(mockEmbed).toHaveBeenCalledTimes(2);
+    expect(result).toEqual([mockEmbedding, mockEmbedding]);
+  });
+
+  it("ensureModelExists() does not pull when model is already present", async () => {
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    await embedder.embed("trigger ensureModelExists");
+
+    expect(mockList).toHaveBeenCalled();
+    expect(mockPull).not.toHaveBeenCalled();
+  });
+
+  it("ensureModelExists() pulls model when not found locally", async () => {
+    mockList.mockResolvedValueOnce({ models: [] });
+
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    await embedder.embed("trigger ensureModelExists");
+
+    expect(mockPull).toHaveBeenCalledWith({ model: "nomic-embed-text:latest" });
+  });
+
+  it("ensureModelExists() normalizes model name with :latest tag", async () => {
+    mockList.mockResolvedValue({
+      models: [{ name: "nomic-embed-text:latest" }],
+    });
+
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text",
+    });
+
+    await embedder.embed("trigger ensureModelExists");
+
+    expect(mockPull).not.toHaveBeenCalled();
+  });
+
+  it("embed() throws when embeddings array is empty", async () => {
+    mockEmbed.mockResolvedValueOnce({
+      model: "nomic-embed-text:latest",
+      embeddings: [],
+    });
+
+    const embedder = new OllamaEmbedder({
+      model: "nomic-embed-text:latest",
+    });
+
+    await expect(embedder.embed("text")).rejects.toThrow(
+      "Ollama embed() returned no embeddings",
+    );
+  });
+});

mem0/embeddings/ollama.py

@@ -31,12 +31,21 @@ class OllamaEmbedding(EmbeddingBase):
         self.client = Client(host=self.config.ollama_base_url)
         self._ensure_model_exists()
 
+    @staticmethod
+    def _normalize_model_name(name: str) -> str:
+        return name if ":" in name else f"{name}:latest"
+
     def _ensure_model_exists(self):
         """
         Ensure the specified model exists locally. If not, pull it from Ollama.
         """
         local_models = self.client.list()["models"]
-        if not any(model.get("name") == self.config.model or model.get("model") == self.config.model for model in local_models):
+        target = self._normalize_model_name(self.config.model)
+        if not any(
+            self._normalize_model_name(model.get("name", "")) == target
+            or self._normalize_model_name(model.get("model", "")) == target
+            for model in local_models
+        ):
             self.client.pull(self.config.model)
 
     def embed(self, text, memory_action: Optional[Literal["add", "search", "update"]] = None):
@@ -49,5 +58,8 @@ class OllamaEmbedding(EmbeddingBase):
         Returns:
             list: The embedding vector.
         """
-        response = self.client.embeddings(model=self.config.model, prompt=text)
-        return response["embedding"]
+        response = self.client.embed(model=self.config.model, input=text)
+        embeddings = response.get("embeddings") or []
+        if not embeddings:
+            raise ValueError(f"Ollama embed() returned no embeddings for model '{self.config.model}'")
+        return embeddings[0]

pyproject.toml

@@ -62,7 +62,7 @@ llms = [
     "together>=0.2.10",
     "litellm>=1.74.0",
     "openai>=1.90.0",
-    "ollama>=0.1.0",
+    "ollama>=0.3.0",
     "vertexai>=0.1.0",
     "google-generativeai>=0.3.0",
     "google-genai>=1.0.0",

tests/embeddings/test_ollama_embeddings.py

@@ -19,13 +19,13 @@ def test_embed_text(mock_ollama_client):
     config = BaseEmbedderConfig(model="nomic-embed-text", embedding_dims=512)
     embedder = OllamaEmbedding(config)
 
-    mock_response = {"embedding": [0.1, 0.2, 0.3, 0.4, 0.5]}
-    mock_ollama_client.embeddings.return_value = mock_response
+    mock_response = {"embeddings": [[0.1, 0.2, 0.3, 0.4, 0.5]]}
+    mock_ollama_client.embed.return_value = mock_response
 
     text = "Sample text to embed."
     embedding = embedder.embed(text)
 
-    mock_ollama_client.embeddings.assert_called_once_with(model="nomic-embed-text", prompt=text)
+    mock_ollama_client.embed.assert_called_once_with(model="nomic-embed-text", input=text)
 
     assert embedding == [0.1, 0.2, 0.3, 0.4, 0.5]
 
@@ -41,3 +41,22 @@ def test_ensure_model_exists(mock_ollama_client):
     embedder._ensure_model_exists()
 
     mock_ollama_client.pull.assert_called_once_with("nomic-embed-text")
+
+
+def test_ensure_model_exists_normalizes_latest_tag(mock_ollama_client):
+    """Model 'nomic-embed-text' should match 'nomic-embed-text:latest' from ollama list."""
+    mock_ollama_client.list.return_value = {"models": [{"name": "nomic-embed-text:latest"}]}
+    config = BaseEmbedderConfig(model="nomic-embed-text", embedding_dims=512)
+    OllamaEmbedding(config)
+
+    mock_ollama_client.pull.assert_not_called()
+
+
+def test_embed_empty_response_raises(mock_ollama_client):
+    config = BaseEmbedderConfig(model="nomic-embed-text", embedding_dims=512)
+    embedder = OllamaEmbedding(config)
+
+    mock_ollama_client.embed.return_value = {"embeddings": []}
+
+    with pytest.raises(ValueError, match="returned no embeddings"):
+        embedder.embed("some text")