htwkalender/datamanager/backend/dbx/db.go

package dbx

import (
	"context"
	"database/sql"
	"github.com/neo4j/neo4j-go-driver/v5/neo4j"
	"log/slog"
)

type (
	DB struct {
		driver neo4j.DriverWithContext
		ctx    context.Context
	}

	// Errors represents a list of errors.
	Errors []error
)

func NewDB(username string, password string) *DB {
	driver, err := neo4j.NewDriverWithContext("bolt://localhost:7687", neo4j.BasicAuth(username, password, ""))
	if err != nil {
		slog.Error("Failed to create a new driver: %v", err)
		return nil
	}

	return &DB{
		driver: driver,
		ctx:    context.Background(),
	}
}

// Context returns the context associated with the DB instance.
// It returns nil if no context is associated.
func (db *DB) Context() context.Context {
	return db.ctx
}

// Close closes the database, releasing any open resources.
func (db *DB) Close() error {
	if db.driver != nil {
		return db.driver.Close(db.ctx)
	}
	return nil

}

// Executor prepares, executes, or queries a SQL statement.
type Executor interface {
	Query(query string, args ...interface{}) (*neo4j.ResultWithContext, error)
	// QueryContext queries a SQL statement with the given context
	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
	// Prepare creates a prepared statement
	Prepare(query string) (*sql.Stmt, error)
}

// Query represents a neo4j query that can be executed.
type Query struct {
	Executor          Executor
	cypher, rawCypher string
}

func helloWorld(ctx context.Context, uri, username, password string) (string, error) {
	driver, err := neo4j.NewDriverWithContext(uri, neo4j.BasicAuth(username, password, ""))
	if err != nil {
		return "", err
	}

	session := driver.NewSession(ctx, neo4j.SessionConfig{AccessMode: neo4j.AccessModeWrite})

	greeting, err := session.ExecuteWrite(ctx, func(transaction neo4j.ManagedTransaction) (any, error) {
		result, err := transaction.Run(ctx,
			"CREATE (a:Greeting) SET a.message = $message RETURN a.message + ', from node ' + id(a)",
			map[string]any{"message": "hello, world"})
		if err != nil {
			return nil, err
		}

		if result.Next(ctx) {
			return result.Record().Values[0], nil
		}

		return nil, result.Err()
	})
	if err != nil {
		return "", err
	}

	return greeting.(string), nil
}