Run your own transactions

When querying the database with ExecuteQuery(), the driver automatically creates a transaction. A transaction is a unit of work that is either committed in its entirety or rolled back on failure. You can include multiple Cypher statements in a single query, as for example when using MATCH and MERGE in sequence to update the database, but you cannot have multiple queries and interleave some client-logic in between them.

For these more advanced use-cases, the driver provides functions to take full control over the transaction lifecycle.

Create a session

Before running a transaction, you need to obtain a session. Sessions act as concrete query channels between the driver and the server, and ensure causal consistency is enforced.

Sessions are created with the method DriverWithContext.NewSession(). Use the second argument to alter the session’s configuration, among which for example the target database. For further configuration parameters, see Session configuration.

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

Session creation is a lightweight operation, so sessions can be created and destroyed without significant cost. Always close sessions when you are done with them.

Sessions are not thread safe: you can share the main DriverWithContext object across threads, but make sure each routine creates its own sessions.

Run a managed transaction

You can think of managed transactions as a way of unwrapping the flow of ExecuteQuery() and being able to specify its desired behavior in more places.

A transaction can contain any number of queries. As Neo4j is ACID compliant, queries within a transaction will either be executed as a whole or not at all: you cannot get a part of the transaction succeeding and another failing. Use transactions to group together related queries which work together to achieve a single logical database operation.

A managed transaction is created with the methods SessionWithContext.ExecuteRead() and SessionWithContext.ExecuteWrite(), depending on whether you want to retrieve data from the database or alter it. Both methods take a transaction function callback, which is responsible for actually carrying out the queries and processing the result.

Retrieve people whose name starts with Al

session := driver.NewSession(ctx, neo4j.SessionConfig{DatabaseName: "neo4j"})  (1)
defer session.Close(ctx)
people, err := session.ExecuteRead(ctx,  (2)
    func(tx neo4j.ManagedTransaction) (any, error) {  (3)
        result, err := tx.Run(ctx, `  (4)
            MATCH (p:Person) WHERE p.name STARTS WITH $filter
            RETURN p.name AS name ORDER BY name
            `, map[string]any{
                "filter": "Al",
            })
        if err != nil {
            return nil, err
        }
        records, err := result.Collect(ctx)  (5)
        if err != nil {
            return nil, err
        }
        return records, nil
    })
for _, person := range people.([]*neo4j.Record) {
    fmt.Println(person.AsMap())
}

1	Create a session. A single session can be the container for multiple queries. Remember to close it when done (here we `defer` its closure just after opening).
2	The `.ExecuteRead()` (or `.ExecuteWrite()`) method is the entry point into a transaction.
3	The transaction function callback is responsible of running queries.
4	Use the method `ManagedTransaction.Run()` to run queries. Each query run returns a `ResultWithContext` object.
5	Process the result using any of the methods on `ResultWithContext`. The method `.Collect()` retrieves all records into a list.

Do not hardcode or concatenate parameters directly into the query. Use query parameters instead, both for performance and security reasons.

Transaction functions should never return the result object directly. Instead, always process the result in some way. Within a transaction function, a return statement where error is nil results in the transaction being committed, while the transaction is automatically rolled back if the returned error value is not nil.

A transaction with multiple queries, client logic, and potential roll backs

package main

import (
    "fmt"
    "context"
    "strconv"
    "errors"
    "github.com/neo4j/neo4j-go-driver/v5/neo4j"
)

func main() {
    ctx := context.Background()
    var employeeThreshold int64 = 10  // Neo4j's integer maps to Go's int64

    // Connection to database
    dbUri := "<URI for Neo4j database>"
    dbUser := "<Username>"
    dbPassword := "<Password>"
    driver, err := neo4j.NewDriverWithContext(
        dbUri,
        neo4j.BasicAuth(dbUser, dbPassword, ""))
    if err != nil {
        panic(err)
    }
    defer driver.Close(ctx)
    err = driver.VerifyConnectivity(ctx)
    if err != nil {
        panic(err)
    }

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

    // Create 100 people and assign them to various organizations
    for i := 0; i < 100; i++ {
        name := "Thor" + strconv.Itoa(i)
        orgId, err := session.ExecuteWrite(ctx,
            func(tx neo4j.ManagedTransaction) (any, error) {
                var orgId string

                // Create new Person node with given name, if not exists already
                _, err := tx.Run(
                    ctx,
                    "MERGE (p:Person {name: $name})",
                    map[string]any{
                        "name": name,
                    })
                if err != nil {
                    return nil, err
                }

                // Obtain most recent organization ID and the number of people linked to it
                result, err := tx.Run(
                    ctx, `
                    MATCH (o:Organization)
                    RETURN o.id AS id, COUNT{(p:Person)-[r:WORKS_FOR]->(o)} AS employeesN
                    ORDER BY o.createdDate DESC
                    LIMIT 1
                    `, nil)
                if err != nil {
                    return nil, err
                }
                org, err := result.Single(ctx)

                // If no organization exists, create one and add Person to it
                if org == nil {
                    orgId, _ = createOrganization(ctx, tx)
                    fmt.Println("No orgs available, created", orgId)
                    err = addPersonToOrganization(ctx, tx, name, orgId)
                    if err != nil {
                        return nil, errors.New("Failed to add person to new org")
                        // Transaction will roll back
                        // -> not even Person and/or Organization is created!
                    }
                } else {
                    orgId = org.AsMap()["id"].(string)
                    if employeesN := org.AsMap()["employeesN"].(int64);
                       employeesN == 0 {
                        return nil, errors.New("Most recent organization is empty")
                        // Transaction will roll back
                        // -> not even Person is created!
                    }

                    // If org does not have too many employees, add this Person to it
                    if employeesN := org.AsMap()["employeesN"].(int64);
                       employeesN < employeeThreshold {
                        err = addPersonToOrganization(ctx, tx, name, orgId)
                        if err != nil {
                            return nil, err
                            // Transaction will roll back
                            // -> not even Person is created!
                        }
                    // Otherwise, create a new Organization and link Person to it
                    } else {
                        orgId, err = createOrganization(ctx, tx)
                        if err != nil {
                            return nil, err
                            // Transaction will roll back
                            // -> not even Person is created!
                        }
                        fmt.Println("Latest org is full, created", orgId)
                        err = addPersonToOrganization(ctx, tx, name, orgId)
                        if err != nil {
                            return nil, err
                            // Transaction will roll back
                            // -> not even Person and/or Organization is created!
                        }
                    }
                }
                // Return the Organization ID to which the new Person ends up in
                return orgId, nil
            })
        if err != nil {
            fmt.Println(err)
        } else {
            fmt.Println("User", name, "added to organization", orgId)
        }
    }
}

func createOrganization(ctx context.Context, tx neo4j.ManagedTransaction) (string, error) {
    result, err := tx.Run(
        ctx, `
        CREATE (o:Organization {id: randomuuid(), createdDate: datetime()})
        RETURN o.id AS id
        `, nil)
    if err != nil {
        return "", err
    }
    org, err := result.Single(ctx)
    if err != nil {
        return "", err
    }
    orgId, _ := org.AsMap()["id"]
    return orgId.(string), err
}

func addPersonToOrganization(ctx context.Context, tx neo4j.ManagedTransaction, personName string, orgId string) (error) {
    _, err := tx.Run(
        ctx, `
        MATCH (o:Organization {id: $orgId})
        MATCH (p:Person {name: $name})
        MERGE (p)-[:WORKS_FOR]->(o)
        `, map[string]any{
            "orgId": orgId,
            "name": personName,
        })
    return err
}

Should a transaction fail for a reason that the driver deems transient, it automatically retries to run the transaction function (with an exponentially increasing delay). For this reason, transaction functions must be idempotent (i.e., they should produce the same effect when run several times), because you do not know upfront how many times they are going to be executed. In practice, this means that you should not edit nor rely on globals, for example. Note that although transactions functions might be executed multiple times, the queries inside it will always run only once.

A session can chain multiple transactions, but only one single transaction can be active within a session at any given time. To maintain multiple concurrent transactions, use multiple concurrent sessions.

Run an explicit transaction

You can achieve full control over transactions by manually beginning one with the method SessionWithContext.BeginTransaction(). You run queries inside an explicit transaction with the method ExplicitTransaction.Run().

session := driver.NewSession(ctx, neo4j.SessionConfig{DatabaseName: "neo4j"})
defer session.Close(ctx)
tx, err := session.BeginTransaction(ctx)
if err != nil {
    panic(err)
}
    // use tx.Run() to run queries
    //     tx.Commit() to commit the transaction
    //     tx.Rollback() to rollback the transaction

Closing an explicit transaction can either happen automatically upon successful return, or can be explicitly controlled through the methods ExplicitTransaction.Commit() and ExplicitTransaction.Rollback().

Explicit transactions are most useful for applications that need to distribute Cypher execution across multiple functions for the same transaction, or for applications that need to run multiple queries within a single transaction but without the automatic retries provided by managed transactions.

A sketch of an explicit transaction interacting with external APIs

package main

import (
    "fmt"
    "context"
    "github.com/neo4j/neo4j-go-driver/v5/neo4j"
)

func main() {
    ctx := context.Background()

    // Connection to database
    dbUri := "<URI for Neo4j database>"
    dbUser := "<Username>"
    dbPassword := "<Password>"
    driver, err := neo4j.NewDriverWithContext(
        dbUri,
        neo4j.BasicAuth(dbUser, dbPassword, ""))
    if err != nil {
        panic(err)
    }
    defer driver.Close(ctx)
    err = driver.VerifyConnectivity(ctx)
    if err != nil {
        panic(err)
    }
    customerId, err := createCustomer(ctx, driver)
    if err != nil {
        panic(err)
    }
    otherBankId := 42
    transferToOtherBank(ctx, driver, customerId, otherBankId, 999)
}

func createCustomer(ctx context.Context, driver neo4j.DriverWithContext) (string, error) {
    result, err := neo4j.ExecuteQuery(ctx, driver, `
    MERGE (c:Customer {id: randomUUID()})
    RETURN c.id AS id
    `, nil,
    neo4j.EagerResultTransformer,
    neo4j.ExecuteQueryWithDatabase("neo4j"))
    if err != nil {
        return "", err
    }
    customerId, _ := result.Records[0].Get("id")
    return customerId.(string), err
}

func transferToOtherBank(ctx context.Context, driver neo4j.DriverWithContext, customerId string, otherBankId int, amount float32) {
    session := driver.NewSession(ctx, neo4j.SessionConfig{DatabaseName: "neo4j"})
    defer session.Close(ctx)
    tx, err := session.BeginTransaction(ctx)
    if err != nil {
        panic(err)
    }

    if ! customerBalanceCheck(ctx, tx, customerId, amount) {
        // give up
        return
    }

    otherBankTransferApi(ctx, customerId, otherBankId, amount)
    // Now the money has been transferred => can't rollback anymore
    // (cannot rollback external services interactions)

    err = decreaseCustomerBalance(ctx, tx, customerId, amount)
    if err != nil {
        requestInspection(ctx, customerId, otherBankId, amount, err)
    }
    err = tx.Commit(ctx)
    if err != nil {
        requestInspection(ctx, customerId, otherBankId, amount, err)
    }
}

func customerBalanceCheck(ctx context.Context, tx neo4j.ExplicitTransaction, customerId string, amount float32) (bool) {
    result, err := tx.Run(ctx, `
        MATCH (c:Customer {id: $id})
        RETURN c.balance >= $amount AS sufficient
        `, map[string]any{
            "id": customerId,
            "amount": amount,
        })
    if err == nil {
        return false
    }
    record, err := result.Single(ctx)
    if err == nil {
        return false
    }
    sufficient := record.AsMap()["sufficient"]
    return sufficient.(bool)
}

func otherBankTransferApi(ctx context.Context, customerId string, otherBankId int, amount float32) {
    // make some API call to other bank
}

func decreaseCustomerBalance(ctx context.Context, tx neo4j.ExplicitTransaction, customerId string, amount float32) (error) {
    _, err := tx.Run(ctx, `
        MATCH (c:Customer {id: $id})
        SET c.balance = c.balance - $amount
        `, map[string]any{
            "id": customerId,
            "amount": amount,
        })
    return err
}

func requestInspection(ctx context.Context, customerId string, otherBankId int, amount float32, err error) {
    // manual cleanup required; log this or similar
    fmt.Println("WARNING: transaction rolled back due to exception:", err)
    fmt.Println("customerId:", customerId, "otherBankId:", otherBankId, "amount:", amount)
}

Process query results

The driver’s output of a query is a ResultWithContext object, which does not directly contain the result records. Rather, it encapsulates the Cypher result in a rich data structure that requires some parsing on the client side.

When working with a query result, there are two things to keep in mind:

The result records are not immediately and entirely fetched and returned by the server. Instead, results come as a lazy stream. In particular, when the driver receives some records from the server, they are initially buffered in a background queue. Records stay in the buffer until they are consumed by the application, at which point they are removed from the buffer. When no more records are available, the result is exhausted.
The result acts as a cursor. This means that there is no way to retrieve a previous record from the stream, unless you saved it in an auxiliary data structure.

The easiest way of processing a result is by calling .Collect(ctx) on it, which yields an array of Record objects. Otherwise, a ResultWithContext object implements a number of methods for processing records. The most commonly needed ones are listed below.

Name Description

Name	Description
`Collect(ctx) ([]*Record, error)`	Return the remainder of the result as a list.
`Single(ctx) (*Record, error)`	Return the next and only remaining record, or `nil`. Calling this method always exhausts the result. If more (or less) than one record is available, a non-`nil` error is returned.
`Record() *Record`	Return the current record.
`Next(ctx) bool`	Return `true` if there is a record to be processed after the current one. In that case, it also advances the result iterator.
`Consume(ctx) (ResultSummary, error)`	Return the query result summary. It exhausts the result, so should only be called when data processing is over.

Collect(ctx) ([]*Record, error)

Return the remainder of the result as a list.

Single(ctx) (*Record, error)

Return the next and only remaining record, or nil. Calling this method always exhausts the result.

If more (or less) than one record is available, a non-nil error is returned.

Record() *Record

Return the current record.

Next(ctx) bool

Return true if there is a record to be processed after the current one. In that case, it also advances the result iterator.

Consume(ctx) (ResultSummary, error)

Return the query result summary. It exhausts the result, so should only be called when data processing is over.

For a complete list of ResultWithContext methods, see API documentation — ResultWithContext.

Session configuration

Database selection

It is recommended to always specify the database explicitly with the configuration parameter DatabaseName upon session creation, even on single-database instances. This allows the driver to work more efficiently, as it does not have to resolve the home database first. If no database is given, the default database set in the Neo4j instance settings is used.

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

Do not rely on the USE Cypher clause for database selection with the driver.

Request routing

In a cluster environment, all sessions are opened in write mode, routing them to a writer. You can change this by explicitly setting the configuration parameter AccessMode to either neo4j.AccessModeRead or neo4j.AccessModeWrite. Note that .ExecuteRead() and .ExecuteWrite() automatically override the session’s default access mode.

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

Although executing a write query in read mode likely results in a runtime error, you should not rely on this for access control. The difference between the two modes is that read transactions will be routed to any node of a cluster, whereas write ones will be directed to the leader. Still, depending on the server version and settings, the server might allow none, some, or all write statements to be executed even in read transactions.

Similar remarks hold for the .ExecuteRead() and .ExecuteWrite() methods.

Run queries as a different user (impersonation)

You can execute a query under the security context of a different user with the configuration parameter ImpersonatedUser, specifying the name of the user to impersonate. For this to work, the user under which the DriverWithContext was created needs to have the appropriate permissions. Impersonating a user is cheaper than creating a new DriverWithContext object.

session := driver.NewSession(ctx, neo4j.SessionConfig{
    DatabaseName: "neo4j",
    ImpersonatedUser: "<somebodyElse>",
})

When impersonating a user, the query is run within the complete security context of the impersonated user and not the authenticated user (i.e., home database, permissions, etc.).

Transaction configuration

You can exert further control on transactions by providing configuration callbacks to .ExecuteRead(), .ExecuteWrite(), and .BeginTransaction(). Use them to specify:

a transaction timeout (in seconds). Transactions that run longer will be terminated by the server. The default value is set on the server side. The minimum value is one millisecond.
a map of metadata that gets attached to the transaction. These metadata get logged in the server query.log, and are visible in the output of the SHOW TRANSACTIONS Cypher command. Use this to tag transactions.

session := driver.NewSession(ctx, neo4j.SessionConfig{DatabaseName: "neo4j"})
defer session.Close(ctx)
people, err := session.ExecuteRead(ctx,
    func(tx neo4j.ManagedTransaction) (any, error) {
        result, _ := tx.Run(ctx, "MATCH (:Person) RETURN count(*) AS n", nil)
        return result.Collect(ctx)
    },
    neo4j.WithTxTimeout(5*time.Second),  // remember to import `time`
    neo4j.WithTxMetadata(map[string]any{"appName": "peopleTracker"}))

Close sessions

Each connection pool has a finite number of sessions, so if you open sessions without ever closing them, your application could run out of them. It is thus recommended to call session.Close() with the defer keyword as soon as you create a new session, to be sure it will be closed in all cases. When a session is closed, it is returned to the connection pool to be later reused.

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

There are corner-cases in which session closure might return an error, so you may want to catch those cases as well.

Glossary

LTS: A Long Term Support release is one guaranteed to be supported for a number of years. Neo4j 4.4 is LTS, and Neo4j 5 will also have an LTS version.
Aura: Aura is Neo4j’s fully managed cloud service. It comes with both free and paid plans.
Cypher: Cypher is Neo4j’s graph query language that lets you retrieve data from the database. It is like SQL, but for graphs.
APOC: Awesome Procedures On Cypher (APOC) is a library of (many) functions that can not be easily expressed in Cypher itself.
Bolt: Bolt is the protocol used for interaction between Neo4j instances and drivers. It listens on port 7687 by default.
ACID: Atomicity, Consistency, Isolation, Durability (ACID) are properties guaranteeing that database transactions are processed reliably. An ACID-compliant DBMS ensures that the data in the database remains accurate and consistent despite failures.
eventual consistency: A database is eventually consistent if it provides the guarantee that all cluster members will, at some point in time, store the latest version of the data.
causal consistency: A database is causally consistent if read and write queries are seen by every member of the cluster in the same order. This is stronger than eventual consistency.
NULL: The null marker is not a type but a placeholder for absence of value. For more information, see Cypher → Working with null.
transaction: A transaction is a unit of work that is either committed in its entirety or rolled back on failure. An example is a bank transfer: it involves multiple steps, but they must all succeed or be reverted, to avoid money being subtracted from one account but not added to the other.
backpressure: Backpressure is a force opposing the flow of data. It ensures that the client is not being overwhelmed by data faster than it can handle.
transaction function: A transaction function is a callback executed by an ExecuteRead or ExecuteWrite call. The driver automatically re-executes the callback in case of server failure.
DriverWithContext: A DriverWithContext object holds the details required to establish connections with a Neo4j database.