feat(milvus): make distance metric type configurable

packages/components/nodes/vectorstores/Milvus/Milvus.test.ts

@@ -0,0 +1,58 @@
+import { MetricType } from '@zilliz/milvus2-sdk-node'
+
+// getBaseClasses(Milvus) is called in the node constructor; stub the utils module
+// so the test does not pull the full src/utils dependency graph.
+jest.mock('../../../src/utils', () => ({
+    getBaseClasses: jest.fn(() => ['Milvus', 'VectorStore']),
+    getCredentialData: jest.fn(),
+    getCredentialParam: jest.fn(),
+    FLOWISE_CHATID: 'chatId'
+}))
+
+const { nodeClass: Milvus_VectorStores, resolveMilvusMetricType } = require('./Milvus')
+
+describe('Milvus resolveMilvusMetricType', () => {
+    it('maps L2 (any case) to MetricType.L2', () => {
+        expect(resolveMilvusMetricType('L2')).toBe(MetricType.L2)
+        expect(resolveMilvusMetricType('l2')).toBe(MetricType.L2)
+    })
+
+    it('maps COSINE (any case) to MetricType.COSINE', () => {
+        expect(resolveMilvusMetricType('COSINE')).toBe(MetricType.COSINE)
+        expect(resolveMilvusMetricType('cosine')).toBe(MetricType.COSINE)
+        expect(resolveMilvusMetricType(' Cosine ')).toBe(MetricType.COSINE)
+    })
+
+    it('maps IP (any case) to MetricType.IP', () => {
+        expect(resolveMilvusMetricType('IP')).toBe(MetricType.IP)
+        expect(resolveMilvusMetricType('ip')).toBe(MetricType.IP)
+    })
+
+    it('falls back to L2 for empty, undefined, or unknown input (backward compatible)', () => {
+        expect(resolveMilvusMetricType(undefined)).toBe(MetricType.L2)
+        expect(resolveMilvusMetricType('')).toBe(MetricType.L2)
+        expect(resolveMilvusMetricType('HAMMING')).toBe(MetricType.L2)
+    })
+})
+
+describe('Milvus node Metric Type input', () => {
+    let node: any
+
+    beforeEach(() => {
+        node = new Milvus_VectorStores()
+    })
+
+    it('exposes a metricType options input with L2/COSINE/IP and an L2 default', () => {
+        const input = node.inputs.find((i: any) => i.name === 'metricType')
+        expect(input).toBeDefined()
+        expect(input.type).toBe('options')
+        expect(input.default).toBe('L2')
+        const optionNames = input.options.map((o: any) => o.name)
+        expect(optionNames).toEqual(['L2', 'COSINE', 'IP'])
+    })
+
+    it('keeps the metricType input optional so existing flows are unaffected', () => {
+        const input = node.inputs.find((i: any) => i.name === 'metricType')
+        expect(input.optional).toBe(true)
+    })
+})

packages/components/nodes/vectorstores/Milvus/Milvus.ts

@@ -11,6 +11,25 @@ interface InsertRow {
     [x: string]: string | number[]
 }
 
+/**
+ * Resolve a user-provided metric type string to a Milvus metric type.
+ * Accepts the values exposed by the node's "Metric Type" input (L2, COSINE, IP),
+ * case-insensitively, and falls back to L2 for empty or unrecognized input so
+ * existing flows keep their previous behavior. Returns the string-literal union
+ * used by @langchain/community's Milvus `indexCreateParams.metric_type`.
+ */
+const resolveMilvusMetricType = (value?: string): 'L2' | 'COSINE' | 'IP' => {
+    switch ((value ?? '').trim().toUpperCase()) {
+        case 'COSINE':
+            return 'COSINE'
+        case 'IP':
+            return 'IP'
+        case 'L2':
+        default:
+            return 'L2'
+    }
+}
+
 class Milvus_VectorStores implements INode {
     label: string
     name: string
@@ -28,7 +47,7 @@ class Milvus_VectorStores implements INode {
     constructor() {
         this.label = 'Milvus'
         this.name = 'milvus'
-        this.version = 2.1
+        this.version = 2.2
         this.type = 'Milvus'
         this.icon = 'milvus.svg'
         this.category = 'Vector Stores'
@@ -112,6 +131,21 @@ class Milvus_VectorStores implements INode {
                 additionalParams: true,
                 optional: true
             },
+            {
+                label: 'Metric Type',
+                name: 'metricType',
+                description:
+                    'Distance metric used when creating the index on upsert and when querying. Must match the metric the Milvus collection was created with. Defaults to L2.',
+                type: 'options',
+                options: [
+                    { label: 'L2 (Euclidean)', name: 'L2' },
+                    { label: 'Cosine Similarity', name: 'COSINE' },
+                    { label: 'Inner Product (IP)', name: 'IP' }
+                ],
+                default: 'L2',
+                additionalParams: true,
+                optional: true
+            },
             {
                 label: 'Secure',
                 name: 'secure',
@@ -194,6 +228,9 @@ class Milvus_VectorStores implements INode {
             // partition
             const partitionName = nodeData.inputs?.milvusPartition ?? '_default'
 
+            // metric type
+            const metricType = resolveMilvusMetricType(nodeData.inputs?.metricType as string)
+
             // init MilvusLibArgs
             const milVusArgs: MilvusLibArgs = {
                 url: address,
@@ -229,7 +266,13 @@ class Milvus_VectorStores implements INode {
             }
 
             try {
-                const vectorStore = await MilvusUpsert.fromDocuments(finalDocs, embeddings, milVusArgs)
+                // Mirror MilvusUpsert.fromDocuments, but inject the configured metric type
+                // into indexCreateParams before the index is created on first upsert.
+                const vectorStore = new MilvusUpsert(embeddings, milVusArgs)
+                if (vectorStore.indexCreateParams) {
+                    vectorStore.indexCreateParams.metric_type = metricType
+                }
+                await vectorStore.addDocuments(finalDocs)
 
                 // Avoid Illegal Invocation
                 vectorStore.similaritySearchVectorWithScore = async (query: number[], k: number, filter?: string) => {
@@ -276,6 +319,9 @@ class Milvus_VectorStores implements INode {
         // partition
         const partitionName = nodeData.inputs?.milvusPartition ?? '_default'
 
+        // metric type
+        const metricType = resolveMilvusMetricType(nodeData.inputs?.metricType as string)
+
         // init MilvusLibArgs
         const milVusArgs: MilvusLibArgs = {
             url: address,
@@ -308,6 +354,12 @@ class Milvus_VectorStores implements INode {
 
         const vectorStore = await Milvus.fromExistingCollection(embeddings, milVusArgs)
 
+        // Ensure the search path uses the user-selected metric (and its matching score
+        // normalization) instead of the LangChain default of L2.
+        if (vectorStore.indexCreateParams) {
+            vectorStore.indexCreateParams.metric_type = metricType
+        }
+
         // Avoid Illegal Invocation
         vectorStore.similaritySearchVectorWithScore = async (query: number[], k: number, filter?: string) => {
             return await similaritySearchVectorWithScore(query, k, vectorStore, milvusFilter, filter)
@@ -471,7 +523,7 @@ class MilvusUpsert extends Milvus {
                 field_name: this.vectorField,
                 index_name: `myindex_${Date.now().toString()}`,
                 index_type: IndexType.AUTOINDEX,
-                metric_type: MetricType.L2
+                metric_type: this.indexCreateParams?.metric_type ?? MetricType.L2
             })
             if (resp.error_code !== ErrorCode.SUCCESS) {
                 throw new Error(`Error creating index`)
@@ -491,4 +543,4 @@ class MilvusUpsert extends Milvus {
     }
 }
 
-module.exports = { nodeClass: Milvus_VectorStores }
+module.exports = { nodeClass: Milvus_VectorStores, resolveMilvusMetricType }