To implement an asynchronous POST method that saves data to a database using Entity Framework (EF) with model validation in a C# .NET WebAPI, follow these steps:
Create a Model with Data Annotations: Define a model class that represents the data you want to save in the database and apply data annotations for validation.
using System.ComponentModel.DataAnnotations;
public class MyEntity
{
public int Id { get; set; }
[Required]
public string Name { get; set; }
[Range(0, 150)] // Example: Age should be between 0 and 150
public int Age { get; set; }
// Add other properties and validation as needed
}- Create a Database Context: Create a database context class that derives from
DbContextin Entity Framework. This class represents your database and includes aDbSetfor yourMyEntityclass.
using Microsoft.EntityFrameworkCore;
public class MyDbContext : DbContext
{
public MyDbContext(DbContextOptions<MyDbContext> options) : base(options)
{
}
public DbSet<MyEntity> MyEntities { get; set; }
}- Configure Database Connection: In your
Startup.cs, configure the database connection in theConfigureServicesmethod:
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<MyDbContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
// Add other services and configurations...
}Make sure to configure your database connection string in the appsettings.json file.
- Create a Service: Create a service that interacts with the database to save data asynchronously and validate the model using EF:
using Microsoft.EntityFrameworkCore;
using System;
using System.Threading.Tasks;
public interface IMyService
{
Task<MyEntity> SaveDataAsync(MyEntity model);
}
public class MyService : IMyService
{
private readonly MyDbContext _dbContext;
public MyService(MyDbContext dbContext)
{
_dbContext = dbContext;
}
public async Task<MyEntity> SaveDataAsync(MyEntity model)
{
if (model == null)
{
throw new ArgumentNullException(nameof(model));
}
if (!IsValidModel(model))
{
throw new ValidationException("Model validation failed.");
}
_dbContext.MyEntities.Add(model);
await _dbContext.SaveChangesAsync();
return model;
}
private bool IsValidModel(MyEntity model)
{
var validationContext = new ValidationContext(model);
var validationResults = new List<ValidationResult>();
return Validator.TryValidateObject(model, validationContext, validationResults, true);
}
}In this example, we added a method IsValidModel to validate the model before saving it to the database.
- Create a Controller: Create a controller that accepts asynchronous POST requests, validates the model, and uses the
IMyServiceto save data to the database:
using Microsoft.AspNetCore.Mvc;
using System;
using System.ComponentModel.DataAnnotations;
using System.Threading.Tasks;
[Route("api/[controller]")]
[ApiController]
public class MyController : ControllerBase
{
private readonly IMyService _myService;
public MyController(IMyService myService)
{
_myService = myService;
}
[HttpPost]
public async Task<IActionResult> Post([FromBody] MyEntity model)
{
if (model == null)
{
return BadRequest("Invalid data");
}
try
{
var savedEntity = await _myService.SaveDataAsync(model);
return Ok(savedEntity);
}
catch (ValidationException ex)
{
return BadRequest(ex.Message);
}
catch (Exception ex)
{
// Handle other exceptions (e.g., database errors)
return StatusCode(500, "Internal server error");
}
}
}Now, when making an asynchronous POST request to “/api/my” with JSON data in the request body, the Post method in the MyController will receive the data, validate it using EF data annotations, and then use the MyService to save it to the database asynchronously.
Adjust the model, database context, and service logic according to specific database schemas and validation requirements.