lc_vector_stores/
neo4j.rs

1// lc-vector-stores/src/neo4j.rs
2//! Neo4j vector store implementation.
3//!
4//! Uses Neo4j's vector index feature (available since Neo4j 5.11) for
5//! similarity search via the Cypher API over HTTP.
6//!
7//! # Example
8//!
9//! ```rust,ignore
10//! use lc_vector_stores::neo4j::{Neo4jVectorStore, Neo4jConfig};
11//!
12//! let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "password", "my_index");
13//! let store = Neo4jVectorStore::new(config);
14//! store.add_documents(docs, embeddings).await?;
15//! let results = store.similarity_search(&query_embedding, 5).await?;
16//! ```
17
18use async_trait::async_trait;
19use serde::Deserialize;
20use serde_json::json;
21
22use crate::{Document, SearchResult, VectorStore, VectorStoreError};
23
24/// Neo4j vector store configuration.
25#[derive(Debug, Clone)]
26pub struct Neo4jConfig {
27    /// Neo4j URI (e.g., "bolt://localhost:7687" or "neo4j://localhost:7687").
28    pub uri: String,
29    /// Username.
30    pub username: String,
31    /// Password.
32    pub password: String,
33    /// Database name (default: "neo4j").
34    pub database: String,
35    /// Node label for vector documents (default: "Document").
36    pub node_label: String,
37    /// Vector index name.
38    pub index_name: String,
39    /// Embedding property name on the node (default: "embedding").
40    pub embedding_property: String,
41    /// Content property name on the node (default: "content").
42    pub content_property: String,
43    /// Metadata property name on the node (default: "metadata").
44    pub metadata_property: String,
45    /// ID property name on the node (default: "id").
46    pub id_property: String,
47}
48
49impl Neo4jConfig {
50    /// Creates a new Neo4jConfig.
51    pub fn new(
52        uri: impl Into<String>,
53        username: impl Into<String>,
54        password: impl Into<String>,
55        index_name: impl Into<String>,
56    ) -> Self {
57        Self {
58            uri: uri.into(),
59            username: username.into(),
60            password: password.into(),
61            database: "neo4j".to_string(),
62            node_label: "Document".to_string(),
63            index_name: index_name.into(),
64            embedding_property: "embedding".to_string(),
65            content_property: "content".to_string(),
66            metadata_property: "metadata".to_string(),
67            id_property: "id".to_string(),
68        }
69    }
70
71    /// Creates config from environment variables.
72    pub fn from_env_result() -> Result<Self, String> {
73        let uri = std::env::var("NEO4J_URI")
74            .map_err(|_| "NEO4J_URI environment variable not set".to_string())?;
75        let username = std::env::var("NEO4J_USERNAME")
76            .map_err(|_| "NEO4J_USERNAME environment variable not set".to_string())?;
77        let password = std::env::var("NEO4J_PASSWORD")
78            .map_err(|_| "NEO4J_PASSWORD environment variable not set".to_string())?;
79        let index_name = std::env::var("NEO4J_VECTOR_INDEX_NAME")
80            .map_err(|_| "NEO4J_VECTOR_INDEX_NAME environment variable not set".to_string())?;
81        let database = std::env::var("NEO4J_DATABASE").unwrap_or_else(|_| "neo4j".to_string());
82        Ok(Self {
83            uri,
84            username,
85            password,
86            database,
87            index_name,
88            ..Default::default()
89        })
90    }
91
92    /// Sets the database name.
93    pub fn with_database(mut self, database: impl Into<String>) -> Self {
94        self.database = database.into();
95        self
96    }
97
98    /// Sets the node label.
99    pub fn with_node_label(mut self, label: impl Into<String>) -> Self {
100        self.node_label = label.into();
101        self
102    }
103
104    /// Sets the embedding property name.
105    pub fn with_embedding_property(mut self, prop: impl Into<String>) -> Self {
106        self.embedding_property = prop.into();
107        self
108    }
109
110    /// Sets the content property name.
111    pub fn with_content_property(mut self, prop: impl Into<String>) -> Self {
112        self.content_property = prop.into();
113        self
114    }
115}
116
117impl Default for Neo4jConfig {
118    fn default() -> Self {
119        Self {
120            uri: "bolt://localhost:7687".to_string(),
121            username: "neo4j".to_string(),
122            password: String::new(),
123            database: "neo4j".to_string(),
124            node_label: "Document".to_string(),
125            index_name: "vector_index".to_string(),
126            embedding_property: "embedding".to_string(),
127            content_property: "content".to_string(),
128            metadata_property: "metadata".to_string(),
129            id_property: "id".to_string(),
130        }
131    }
132}
133
134/// Neo4j vector store.
135///
136/// Communicates with Neo4j via the HTTP transaction API.
137pub struct Neo4jVectorStore {
138    config: Neo4jConfig,
139    client: reqwest::Client,
140}
141
142impl std::fmt::Debug for Neo4jVectorStore {
143    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
144        f.debug_struct("Neo4jVectorStore")
145            .field("uri", &self.config.uri)
146            .field("index", &self.config.index_name)
147            .finish()
148    }
149}
150
151impl Neo4jVectorStore {
152    /// Creates a new Neo4jVectorStore with the given configuration.
153    pub fn new(config: Neo4jConfig) -> Self {
154        Self {
155            config,
156            client: reqwest::Client::new(),
157        }
158    }
159
160    /// Creates from environment variables.
161    pub fn from_env_result() -> Result<Self, String> {
162        Ok(Self::new(Neo4jConfig::from_env_result()?))
163    }
164
165    /// Builds the HTTP API URL for the transaction endpoint.
166    fn tx_url(&self) -> String {
167        // Convert bolt:// or neo4j:// to http:// for the REST API
168        let http_uri = self
169            .config
170            .uri
171            .replace("bolt://", "http://")
172            .replace("neo4j://", "http://")
173            .replace("bolt+s://", "https://")
174            .replace("neo4j+s://", "https://");
175        format!(
176            "{}/db/{}/tx/commit",
177            http_uri.trim_end_matches('/'),
178            self.config.database
179        )
180    }
181
182    /// Executes a Cypher query via the HTTP transaction API.
183    async fn run_query(
184        &self,
185        query: &str,
186        params: serde_json::Value,
187    ) -> Result<Neo4jResponse, VectorStoreError> {
188        let body = json!({
189            "statements": [{
190                "statement": query,
191                "parameters": params,
192            }]
193        });
194
195        let response = self
196            .client
197            .post(self.tx_url())
198            .header("Content-Type", "application/json")
199            .header(
200                "Authorization",
201                format!(
202                    "Basic {}",
203                    base64_encode(format!("{}:{}", self.config.username, self.config.password))
204                ),
205            )
206            .json(&body)
207            .send()
208            .await
209            .map_err(|e| VectorStoreError::ConnectionError(e.to_string()))?;
210
211        let status = response.status();
212        if !status.is_success() {
213            let error_text = response.text().await.unwrap_or_default();
214            return Err(VectorStoreError::ConnectionError(format!(
215                "HTTP {}: {}",
216                status, error_text
217            )));
218        }
219
220        let neo4j_response: Neo4jResponse = response
221            .json()
222            .await
223            .map_err(|e| VectorStoreError::StorageError(e.to_string()))?;
224
225        // Check for Neo4j-level errors
226        if let Some(errors) = &neo4j_response.errors {
227            if !errors.is_empty() {
228                let msg = errors
229                    .iter()
230                    .map(|e| e.message.clone())
231                    .collect::<Vec<_>>()
232                    .join("; ");
233                return Err(VectorStoreError::StorageError(msg));
234            }
235        }
236
237        Ok(neo4j_response)
238    }
239}
240
241/// Base64 encoding helper (no external dependency needed).
242fn base64_encode(input: String) -> String {
243    const CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
244    let bytes = input.as_bytes();
245    let mut result = String::new();
246    let mut i = 0;
247    while i < bytes.len() {
248        let b0 = bytes[i];
249        let b1 = if i + 1 < bytes.len() { bytes[i + 1] } else { 0 };
250        let b2 = if i + 2 < bytes.len() { bytes[i + 2] } else { 0 };
251
252        result.push(CHARSET[((b0 >> 2) & 0x3F) as usize] as char);
253        result.push(CHARSET[(((b0 << 4) | (b1 >> 4)) & 0x3F) as usize] as char);
254        result.push(if i + 1 < bytes.len() {
255            CHARSET[(((b1 << 2) | (b2 >> 6)) & 0x3F) as usize] as char
256        } else {
257            '='
258        });
259        result.push(if i + 2 < bytes.len() {
260            CHARSET[(b2 & 0x3F) as usize] as char
261        } else {
262            '='
263        });
264
265        i += 3;
266    }
267    result
268}
269
270// ---------------------------------------------------------------------------
271// Neo4j HTTP API response types
272// ---------------------------------------------------------------------------
273
274/// Neo4j transaction commit response.
275#[derive(Debug, Deserialize)]
276struct Neo4jResponse {
277    results: Vec<Neo4jResult>,
278    errors: Option<Vec<Neo4jError>>,
279}
280
281#[derive(Debug, Deserialize)]
282struct Neo4jResult {
283    data: Vec<Neo4jRow>,
284}
285
286#[derive(Debug, Deserialize)]
287struct Neo4jRow {
288    row: Vec<serde_json::Value>,
289}
290
291#[derive(Debug, Deserialize)]
292struct Neo4jError {
293    message: String,
294}
295
296#[async_trait]
297impl VectorStore for Neo4jVectorStore {
298    async fn add_documents(
299        &self,
300        documents: Vec<Document>,
301        embeddings: Vec<Vec<f32>>,
302    ) -> Result<Vec<String>, VectorStoreError> {
303        if documents.len() != embeddings.len() {
304            return Err(VectorStoreError::EmbeddingError(
305                "Number of documents and embeddings must match".to_string(),
306            ));
307        }
308
309        let ids: Vec<String> = documents
310            .iter()
311            .map(|doc| {
312                doc.id
313                    .clone()
314                    .unwrap_or_else(|| uuid::Uuid::new_v4().to_string())
315            })
316            .collect();
317
318        // Build UNWIND Cypher for batch insert
319        let rows: Vec<serde_json::Value> = documents
320            .into_iter()
321            .zip(embeddings)
322            .zip(ids.iter())
323            .map(|((doc, vec), id)| {
324                let metadata: serde_json::Value = doc
325                    .metadata
326                    .iter()
327                    .map(|(k, v)| (k.clone(), json!(v)))
328                    .collect();
329                json!({
330                    "id": id,
331                    "content": doc.content,
332                    "embedding": vec,
333                    "metadata": metadata,
334                })
335            })
336            .collect();
337
338        let query = format!(
339            "UNWIND $rows AS row \
340             MERGE (n:{label} {{{id_prop}: row.id}}) \
341             SET n.{content_prop} = row.content, \
342                 n.{embedding_prop} = row.embedding, \
343                 n.{metadata_prop} = row.metadata",
344            label = self.config.node_label,
345            id_prop = self.config.id_property,
346            content_prop = self.config.content_property,
347            embedding_prop = self.config.embedding_property,
348            metadata_prop = self.config.metadata_property,
349        );
350
351        self.run_query(&query, json!({ "rows": rows })).await?;
352
353        Ok(ids)
354    }
355
356    async fn similarity_search(
357        &self,
358        query_embedding: &[f32],
359        k: usize,
360    ) -> Result<Vec<SearchResult>, VectorStoreError> {
361        // Use Neo4j's db.index.vector.queryNodes procedure
362        let query = format!(
363            "CALL db.index.vector.queryNodes($index_name, $k, $query_vector) \
364             YIELD node, score \
365             RETURN node.{id_prop} AS id, \
366                    node.{content_prop} AS content, \
367                    node.{metadata_prop} AS metadata, \
368                    score \
369             ORDER BY score DESC",
370            id_prop = self.config.id_property,
371            content_prop = self.config.content_property,
372            metadata_prop = self.config.metadata_property,
373        );
374
375        let params = json!({
376            "index_name": self.config.index_name,
377            "k": k,
378            "query_vector": query_embedding,
379        });
380
381        let response = self.run_query(&query, params).await?;
382
383        let result = response.results.first();
384        let Some(neo4j_result) = result else {
385            return Ok(Vec::new());
386        };
387
388        let mut search_results = Vec::new();
389        for row in &neo4j_result.data {
390            if row.row.len() >= 4 {
391                let id = row.row[0].as_str().unwrap_or_default().to_string();
392                let content = row.row[1].as_str().unwrap_or_default().to_string();
393                let score = row.row[3].as_f64().unwrap_or(0.0) as f32;
394
395                let mut doc = Document::new(content).with_id(id);
396
397                // Parse metadata from JSON object
398                if let Some(meta_obj) = row.row[2].as_object() {
399                    for (key, value) in meta_obj {
400                        if let Some(s) = value.as_str() {
401                            doc = doc.with_metadata(key, s);
402                        } else {
403                            doc = doc.with_metadata(key, value.to_string());
404                        }
405                    }
406                }
407
408                search_results.push(SearchResult {
409                    document: doc,
410                    score,
411                });
412            }
413        }
414
415        Ok(search_results)
416    }
417
418    async fn get_document(&self, id: &str) -> Result<Option<Document>, VectorStoreError> {
419        let query = format!(
420            "MATCH (n:{label} {{{id_prop}: $id}}) \
421             RETURN n.{content_prop} AS content, n.{metadata_prop} AS metadata",
422            label = self.config.node_label,
423            id_prop = self.config.id_property,
424            content_prop = self.config.content_property,
425            metadata_prop = self.config.metadata_property,
426        );
427
428        let response = self.run_query(&query, json!({ "id": id })).await?;
429
430        let result = response.results.first();
431        let Some(neo4j_result) = result else {
432            return Ok(None);
433        };
434
435        let row = neo4j_result.data.first();
436        let Some(row) = row else {
437            return Ok(None);
438        };
439
440        if row.row.is_empty() {
441            return Ok(None);
442        }
443
444        let content = row.row[0].as_str().unwrap_or_default().to_string();
445        let mut doc = Document::new(content).with_id(id);
446
447        if row.row.len() > 1 {
448            if let Some(meta_obj) = row.row[1].as_object() {
449                for (key, value) in meta_obj {
450                    if let Some(s) = value.as_str() {
451                        doc = doc.with_metadata(key, s);
452                    } else {
453                        doc = doc.with_metadata(key, value.to_string());
454                    }
455                }
456            }
457        }
458
459        Ok(Some(doc))
460    }
461
462    async fn get_embedding(&self, id: &str) -> Result<Option<Vec<f32>>, VectorStoreError> {
463        let query = format!(
464            "MATCH (n:{label} {{{id_prop}: $id}}) \
465             RETURN n.{embedding_prop} AS embedding",
466            label = self.config.node_label,
467            id_prop = self.config.id_property,
468            embedding_prop = self.config.embedding_property,
469        );
470
471        let response = self.run_query(&query, json!({ "id": id })).await?;
472
473        let result = response.results.first();
474        let Some(neo4j_result) = result else {
475            return Ok(None);
476        };
477
478        let row = neo4j_result.data.first();
479        let Some(row) = row else {
480            return Ok(None);
481        };
482
483        if row.row.is_empty() {
484            return Ok(None);
485        }
486
487        let embedding: Vec<f32> = row.row[0]
488            .as_array()
489            .map(|arr| {
490                arr.iter()
491                    .filter_map(|v| v.as_f64().map(|f| f as f32))
492                    .collect()
493            })
494            .unwrap_or_default();
495
496        if embedding.is_empty() {
497            Ok(None)
498        } else {
499            Ok(Some(embedding))
500        }
501    }
502
503    async fn delete_document(&self, id: &str) -> Result<(), VectorStoreError> {
504        let query = format!(
505            "MATCH (n:{label} {{{id_prop}: $id}}) \
506             DETACH DELETE n",
507            label = self.config.node_label,
508            id_prop = self.config.id_property,
509        );
510
511        self.run_query(&query, json!({ "id": id })).await?;
512        Ok(())
513    }
514
515    async fn count(&self) -> usize {
516        let query = format!(
517            "MATCH (n:{label}) RETURN count(n) AS cnt",
518            label = self.config.node_label,
519        );
520
521        let result = self.run_query(&query, json!({})).await;
522        match result {
523            Ok(response) => {
524                if let Some(neo4j_result) = response.results.first() {
525                    if let Some(row) = neo4j_result.data.first() {
526                        if let Some(cnt) = row.row.first() {
527                            return cnt.as_u64().unwrap_or(0) as usize;
528                        }
529                    }
530                }
531                0
532            }
533            Err(_) => 0,
534        }
535    }
536
537    async fn clear(&self) -> Result<(), VectorStoreError> {
538        let query = format!(
539            "MATCH (n:{label}) \
540             DETACH DELETE n",
541            label = self.config.node_label,
542        );
543
544        self.run_query(&query, json!({})).await?;
545        Ok(())
546    }
547}
548
549#[cfg(test)]
550mod tests {
551    use super::*;
552
553    #[test]
554    fn test_config_new() {
555        let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "my_index");
556        assert_eq!(config.uri, "bolt://localhost:7687");
557        assert_eq!(config.username, "neo4j");
558        assert_eq!(config.password, "pass");
559        assert_eq!(config.index_name, "my_index");
560        assert_eq!(config.database, "neo4j");
561    }
562
563    #[test]
564    fn test_config_builder() {
565        let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "idx")
566            .with_database("mydb")
567            .with_node_label("Chunk")
568            .with_embedding_property("vec")
569            .with_content_property("text");
570        assert_eq!(config.database, "mydb");
571        assert_eq!(config.node_label, "Chunk");
572        assert_eq!(config.embedding_property, "vec");
573        assert_eq!(config.content_property, "text");
574    }
575
576    #[test]
577    fn test_config_default() {
578        let config = Neo4jConfig::default();
579        assert_eq!(config.uri, "bolt://localhost:7687");
580        assert_eq!(config.node_label, "Document");
581        assert_eq!(config.embedding_property, "embedding");
582    }
583
584    #[test]
585    fn test_tx_url_bolt() {
586        let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "idx");
587        let store = Neo4jVectorStore::new(config);
588        assert_eq!(store.tx_url(), "http://localhost:7687/db/neo4j/tx/commit");
589    }
590
591    #[test]
592    fn test_tx_url_neo4j_scheme() {
593        let config = Neo4jConfig::new("neo4j://host:7687", "neo4j", "pass", "idx");
594        let store = Neo4jVectorStore::new(config);
595        assert_eq!(store.tx_url(), "http://host:7687/db/neo4j/tx/commit");
596    }
597
598    #[test]
599    fn test_tx_url_bolt_s() {
600        let config = Neo4jConfig::new("bolt+s://host:7687", "neo4j", "pass", "idx");
601        let store = Neo4jVectorStore::new(config);
602        assert_eq!(store.tx_url(), "https://host:7687/db/neo4j/tx/commit");
603    }
604
605    #[test]
606    fn test_tx_url_custom_database() {
607        let config =
608            Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "idx").with_database("mydb");
609        let store = Neo4jVectorStore::new(config);
610        assert_eq!(store.tx_url(), "http://localhost:7687/db/mydb/tx/commit");
611    }
612
613    #[test]
614    fn test_base64_encode() {
615        // "neo4j:password" in base64
616        let encoded = base64_encode("neo4j:password".to_string());
617        assert_eq!(encoded, "bmVvNGo6cGFzc3dvcmQ=");
618    }
619
620    #[test]
621    fn test_base64_encode_empty() {
622        let encoded = base64_encode(String::new());
623        assert_eq!(encoded, "");
624    }
625
626    #[test]
627    fn test_store_new() {
628        let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "idx");
629        let _store = Neo4jVectorStore::new(config);
630    }
631
632    #[test]
633    fn test_store_debug() {
634        let config = Neo4jConfig::new("bolt://localhost:7687", "neo4j", "pass", "idx");
635        let store = Neo4jVectorStore::new(config);
636        let debug_str = format!("{:?}", store);
637        assert!(debug_str.contains("Neo4jVectorStore"));
638        assert!(debug_str.contains("idx"));
639    }
640}
lc_vector_stores/neo4j.rs

lc_vector_stores/
neo4j.rs
