neo4j-driver-go-skill

go get github.com/neo4j/neo4j-go-driver/v6

import "os"

uri      := getEnv("NEO4J_URI",      "neo4j://localhost:7687")
user     := getEnv("NEO4J_USERNAME", "neo4j")
password := getEnv("NEO4J_PASSWORD", "")
database := getEnv("NEO4J_DATABASE", "neo4j")

func getEnv(key, fallback string) string {
    if v := os.Getenv(key); v != "" { return v }
    return fallback
}

func NewNeo4jDriver(uri, user, password string) (neo4j.Driver, error) {
    driver, err := neo4j.NewDriver(
        uri, // "neo4j+s://xxx.databases.neo4j.io" for Aura
        neo4j.BasicAuth(user, password, ""),
    )
    if err != nil {
        return nil, fmt.Errorf("create driver: %w", err)
    }
    ctx := context.Background()
    if err := driver.VerifyConnectivity(ctx); err != nil {
        driver.Close(ctx)
        return nil, fmt.Errorf("verify connectivity: %w", err)
    }
    return driver, nil
}

// In main / app teardown:
defer driver.Close(ctx)

result, err := neo4j.ExecuteQuery(ctx, driver,
    `MATCH (p:Person {name: $name})-[:KNOWS]->(friend)
     RETURN friend.name AS name`,
    map[string]any{"name": "Alice"},
    neo4j.EagerResultTransformer,
    neo4j.ExecuteQueryWithDatabase("neo4j"),       // always specify
    neo4j.ExecuteQueryWithReadersRouting(),         // for read queries
)
if err != nil {
    return fmt.Errorf("query people: %w", err)
}

for _, record := range result.Records {
    name, _ := record.Get("name")
    fmt.Println(name)
}
fmt.Println(result.Summary.Counters().NodesCreated())

neo4j.ExecuteQueryWithDatabase("mydb")          // required for performance
neo4j.ExecuteQueryWithReadersRouting()           // route reads to replicas
neo4j.ExecuteQueryWithImpersonatedUser("jane")  // impersonate
neo4j.ExecuteQueryWithoutBookmarkManager()       // opt out of causal consistency

type Person struct {
    Name     string `neo4j:"name"`
    Age      int    `neo4j:"age,omitempty"`  // zero value dropped
    Internal string `neo4j:"-"`              // never sent
}
_, err := neo4j.ExecuteQuery(ctx, driver,
    "MERGE (p:Person {name: $person.name}) SET p += $person",
    map[string]any{"person": Person{Name: "Alice", Age: 30}},
    neo4j.EagerResultTransformer,
    neo4j.ExecuteQueryWithDatabase("neo4j"),
)

session := driver.NewSession(ctx, neo4j.SessionConfig{
    DatabaseName: "neo4j", // always specify
    AccessMode:   neo4j.AccessModeRead,
})
defer session.Close(ctx)

result, err := session.ExecuteRead(ctx,
    func(tx neo4j.ManagedTransaction) (any, error) {
        res, err := tx.Run(ctx,
            `MATCH (p:Person) RETURN p.name AS name LIMIT $limit`,
            map[string]any{"limit": 100},
        )
        if err != nil {
            return nil, err
        }
        var names []string
        for res.Next(ctx) { // lazy — don't Collect() on large sets
            name, _ := res.Record().Get("name")
            names = append(names, name.(string))
        }
        return names, res.Err()
    },
)

session := driver.NewSession(ctx, neo4j.SessionConfig{DatabaseName: "neo4j"})
defer session.Close(ctx)

tx, err := session.BeginTransaction(ctx)
if err != nil {
    return err
}
if err := doPartA(ctx, tx); err != nil {
    tx.Rollback(ctx)
    return err
}
if err := doPartB(ctx, tx); err != nil {
    tx.Rollback(ctx)
    return err
}
return tx.Commit(ctx)

result, err := neo4j.ExecuteQuery(...)
if err != nil {
    var neo4jErr *neo4j.Neo4jError
    if errors.As(err, &neo4jErr) {
        slog.Error("database error", "code", neo4jErr.Code, "msg", neo4jErr.Msg)
    }
    var connErr *neo4j.ConnectivityError
    if errors.As(err, &connErr) {
        slog.Error("connectivity error", "err", connErr)
    }
    return fmt.Errorf("execute query: %w", err)
}

neo4j.IsNeo4jError(err)                // server-side Cypher/database error
neo4j.IsTransactionExecutionLimit(err) // managed tx retries exhausted

// Typed extraction (v6+, preferred):
neo4j.GetRecordValue[string](record, "name")

// Manual extraction:
rawAge, ok := record.Get("age")
if !ok { return errors.New("missing 'age' field") }
age := rawAge.(int64) // Neo4j integers → int64

// Node access:
rawNode, _ := record.Get("p")
node := rawNode.(neo4j.Node)
name := node.Props["name"].(string)
labels := node.Labels // []string

ctx, cancel := context.WithTimeout(parentCtx, 5*time.Second)
defer cancel()
// pass ctx to all driver calls

// Bad: one transaction per record
for _, item := range items {
    neo4j.ExecuteQuery(ctx, driver, writeQuery, item, ...)
}

// Good: UNWIND batch in one transaction
neo4j.ExecuteQuery(ctx, driver,
    `UNWIND $items AS item
     MERGE (n:Node {id: item.id})
     SET n += item`,
    map[string]any{"items": items},
    neo4j.EagerResultTransformer,
    neo4j.ExecuteQueryWithDatabase("neo4j"),
)

// GetRecordValue[T] — extract + cast in one call
name, isNil, err := neo4j.GetRecordValue[string](record, "name")
// isNil=true when OPTIONAL MATCH returned null; err != nil when key absent or wrong type

// CollectTWithContext — map all records to a slice
people, err := neo4j.CollectTWithContext(ctx, result, func(record *neo4j.Record) (Person, error) {
    name, _, err := neo4j.GetRecordValue[string](record, "name")
    age, _, _   := neo4j.GetRecordValue[int64](record, "age")
    return Person{Name: name, Age: int(age)}, err
})

// SingleTWithContext — expect exactly one record (error if 0 or 2+)
person, err := neo4j.SingleTWithContext(ctx, result, func(record *neo4j.Record) (Person, error) {
    name, _, _ := neo4j.GetRecordValue[string](record, "name")
    return Person{Name: name}, nil
})

// GetProperty — typed property from Node or Relationship
node, _, _ := neo4j.GetRecordValue[neo4j.Node](record, "p")
nameVal, err := neo4j.GetProperty[string](node, "name")

type Person struct {
    Name string `neo4j:"name"`
    Age  int    `neo4j:"age"`   // INTEGER converted; lossy conversion → error, not truncation
}

// EagerResult from ExecuteQuery
res, err := neo4j.ExecuteQuery(ctx, driver,
    "MATCH (p:Person) RETURN p.name AS name, p.age AS age LIMIT 25",
    nil, neo4j.EagerResultTransformer, neo4j.ExecuteQueryWithDatabase("neo4j"))
people, err := neo4j.CollectRecordsAs[Person](res.Records)

// Streaming Result inside a transaction
all, err := neo4j.CollectAs[Person](ctx, result)      // all records
person, err := neo4j.SingleAs[Person](ctx, result)    // exactly one record
p, err := neo4j.As[Person](record)                    // single record

// 2D Cartesian (SRID 7203), 3D Cartesian (SRID 9157)
pt2d := neo4j.Point2D{X: 1.23, Y: 4.56, SpatialRefId: 7203}
pt3d := neo4j.Point3D{X: 1.23, Y: 4.56, Z: 7.89, SpatialRefId: 9157}

// 2D WGS-84 (SRID 4326), 3D WGS-84 (SRID 4979)
london := neo4j.Point2D{X: -0.118092, Y: 51.509865, SpatialRefId: 4326}
shard  := neo4j.Point3D{X: -0.0865, Y: 51.5045, Z: 310, SpatialRefId: 4979}

// Pass as parameter
result, err := neo4j.ExecuteQuery(ctx, driver,
    "CREATE (p:Place {location: $loc})",
    map[string]any{"loc": london},
    neo4j.EagerResultTransformer,
    neo4j.ExecuteQueryWithDatabase("neo4j"),
)

// Read from result — assert to Point2D or Point3D
raw, _ := record.Get("location")
if p2d, ok := raw.(neo4j.Point2D); ok {
    fmt.Printf("lon=%f lat=%f srid=%d\n", p2d.X, p2d.Y, p2d.SpatialRefId)
}

// Distance (same SRID only)
result, _ = neo4j.ExecuteQuery(ctx, driver,
    "RETURN point.distance($p1, $p2) AS distance",
    map[string]any{"p1": pt2d, "p2": neo4j.Point2D{X: 10, Y: 10, SpatialRefId: 7203}},
    neo4j.EagerResultTransformer, neo4j.ExecuteQueryWithDatabase("neo4j"),
)
dist, _ := result.Records[0].Get("distance")
fmt.Println(dist.(float64))

neo4j.ExecuteQueryWithDatabase("neo4j")    // in ExecuteQuery
neo4j.SessionConfig{DatabaseName: "neo4j"} // in sessions