Dapper Best Practices: C# Developers' Guide to Database Management

Dapper is an open-source ORM tool that is easy to use and lightweight, which makes it a popular choice for .NET developers. It is designed to work with various databases, including SQL Server, Oracle, MySQL, and PostgreSQL. Dapper is fast and efficient because it does not add any overhead to the data access layer and is very easy to start.

Prerequisites

Before getting started, you must have basic knowledge of the following.

• Basic knowledge of C# programming language
• Docker ORM

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Getting Started

This article will discuss the best practices for using Dapper in your C# applications. These practices will help you to write cleaner, more maintainable, and more performant code when working with databases.

Use Parameterized Queries:

One of the most important best practices when working with databases is to use parameterized queries. Parameterized queries allow you to separate the SQL code from user input, preventing malicious information from being executed as part of the SQL query. Using parameterized queries is easy with Dapper, and it is a best practice that should always be followed.

Here is an example of a parameterized query using Dapper:

connection.Query<Employee>("SELECT * FROM Employees WHERE EmployeeId = @EmployeeId", new { EmployeeId = 1 });

Use Asynchronous Methods:

Dapper supports asynchronous operations, which can improve the performance of your application. Instead of waiting for the database query to complete synchronously, you can use the async/await keywords to execute the query asynchronously. This can help to free up resources and improve the overall responsiveness of your application.

Here is an example of using asynchronous methods with Dapper:

await connection.QueryAsync<Employee>("SELECT * FROM Employees");

Use the Repository Pattern

The Repository pattern is a well-known design pattern separating data access and business logic. Using the Repository pattern with Dapper can help you to organize your code and make it more maintainable. The Repository pattern also makes it easier to test your code, as you can create mock repositories for testing purposes.

Here is an example of using the Repository pattern with Dapper:

public interface IEmployeeRepository
{
    Employee GetById(int id);
    IEnumerable<Employee> GetAll();
}

public class EmployeeRepository : IEmployeeRepository
{
    private readonly IDbConnection _db;
    public EmployeeRepository(IDbConnection db)
    {
        _db = db;
    }
    public Employee GetById(int id)
    {
        return _db.QuerySingleOrDefault<Employee>("SELECT * FROM Employees WHERE EmployeeId = @EmployeeId", new { EmployeeId = id });
    }
    public IEnumerable<Employee> GetAll()
    {
        return _db.Query<Employee>("SELECT * FROM Employees");
    }
}

Use Transactions:

Transactions are essential when you're dealing with data that needs to be consistent. Dapper allows you to use transactions, which can help you maintain your data's integrity. Transactions also make it easier to roll back changes if something goes wrong.

Here is an example of using transactions with Dapper:

using (var transaction = connection.BeginTransaction())
{
    try
    {
        connection.Execute("INSERT INTO Employees (Name, Age) VALUES (@Name, @Age)", new { Name = "John", Age = 30 }, transaction);
        connection.Execute("INSERT INTO Employees (Name, Age) VALUES (@Name, @Age)", new { Name = "Jane", Age = 35 }, transaction);
        transaction.Commit();
    }
    catch
    {
        transaction.Rollback();
        throw;
    }
}

Use Dapper.Contrib

Dapper.Contrib is an open-source library that provides a set of extension methods to Dapper, which can help you to perform CRUD (Create, Read, Update, Delete) operations more efficiently. With Dapper.Contrib, you can use simple methods like Insert, Update, Delete, and Get to perform these operations instead of writing complex SQL queries.

Here is an example of using Dapper.Contrib to performing CRUD operations:

connection.Insert(new Employee { Name = "John", Age = 30 });
connection.Update(new Employee { EmployeeId = 1, Name = "Jane", Age = 35 });
connection.Delete(new Employee { EmployeeId = 1 });
var employee = connection.Get<Employee>(1);

Use Mapping:

Dapper allows you to map query results to C# objects. Mapping can help you work with data more naturally, saving you a lot of time when working with large data sets. Dapper supports automatic and manual mapping, and you can choose the best method for your application.

Here is an example of using manual mapping with Dapper:

public class Employee
{
    public int EmployeeId { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

var employees = connection.Query("SELECT * FROM Employees").Select(x => new Employee
{
    EmployeeId = (int)x.EmployeeId,
    Name = (string)x.Name,
    Age = (int)x.Age
});

Use Connection Pooling

Dapper works well with connection pooling, which can help you improve your application's performance. Connection pooling allows you to reuse existing database connections instead of creating new connections each time you need to access the database. This can reduce the overhead associated with making new connections, and it can help to improve the overall performance of your application.

Here is an example of using connection pooling with Dapper:

var connectionString = "Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;Pooling=true;";
var connection = new SqlConnection(connectionString);

Use Query Helpers

Dapper provides several query helpers that can help you to write more complex queries more efficiently. Query helpers allow you to write difficult questions using simple methods, which can reduce the amount of code you need to write. Query helpers can perform joins, aggregate functions, and other advanced operations.

Here is an example of using query helpers with Dapper:

connection.Query<Employee, Department, Employee>("SELECT e.*, d.* FROM Employees e JOIN Departments d ON e.DepartmentId = d.DepartmentId WHERE e.EmployeeId = @EmployeeId", (employee, department) =>
{
    employee.Department = department;
    return employee;
}, new { EmployeeId = 1 }, splitOn: "DepartmentId");

Use the 'Using' Statement

The 'using' statement is a C# construct that allows you to dispose of resources when they are no longer needed automatically. When working with databases, it is essential to ensure that database connections are properly closed when no longer required. The 'using' statement can help you to do this automatically, ensuring that database connections are closed, and resources are correctly disposed of.

Here is an example of using the 'using' statement with Dapper:

using (var connection = new SqlConnection(connectionString))
{
    connection.Open();
    // Query or Execute statements
}

Use Performance Profiling

Finally, it's essential to use performance profiling tools to identify performance bottlenecks in your application. Dapper is designed to be fast and efficient, but there may be situations where you need to optimize your queries or database schema to improve performance. Performance profiling tools can help you to identify these bottlenecks and make the necessary changes to improve performance.

Conclusion

These best practices can help you to use Dapper more effectively in your C# applications. Following these best practices allows you to write cleaner, more maintainable, and more performant code when working with databases. Use connection pooling to improve performance, use query helpers to write complex queries more efficiently, use the 'using' statement to automatically dispose of resources, and use performance profiling tools to identify performance bottlenecks. By following these best practices, you can make the most of Dapper in your C# applications.

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