How you can implement idempotent APIs in ASP.NET Core

Now let’s get began with our implementation. For our instance, we’ll use a easy purchasing cart software.

Create the mannequin lessons

Within the challenge we created earlier, create the next lessons within the Fashions folder.

public class Product
{
   public int Product_Id { get; set; }
   public string Product_Code { get; set; }
   public string Product_Name { get; set; }
   public double Product_Price { get; set; }
}
public class Order
{
   public int Order_Id { get; set; }
   public Record Merchandise { get; set; }
}
public class KeyStore
{
   public string Key { get; set; }
   public DateTime Expiry { get; set; }
}

Whereas the Product and Order lessons are sometimes utilized in a ShoppingCart software, the KeyStore class is used right here to retailer our idempotency keys. On this implementation, we’ll save these keys within the database (dbContext). Naturally, you may change the implementation to retailer the keys within the cache or some other knowledge retailer.

Create the controller class

Proper-click on the Controllers folder within the Answer Explorer Window and create an API controller referred to as OrderController. Now, enter the next motion technique within the OrderController class. This technique creates a brand new order.

[HttpPost]
public IActionResult CreateOrder([FromBody] Order order, [FromHeader(Name = "X-Idempotency_Key")] string key)
{
    if (string.IsNullOrEmpty(key))
    {
        return BadRequest("Idempotency key's required.");
    }
    if (_dbContext.KeyStore.FirstOrDefault(okay => okay.Key == key)!= null)
    {
        var existingItem = _dbContext.Orders.FirstOrDefault(o => o.Order_Id == order.Order_Id);
        return Battle(new { message = "Request has already been processed.", merchandise = existingItem });
    }
    _dbContext.KeyStore.Add(new KeyStore {Key = key, Expiry = DateTime.Now.AddDays(7)});
    _dbContext.Add(order);
    _dbContext.SaveChanges();
    return Okay(order.Order_Id);
}

Study the code above. An idempotency key’s generated on the consumer facet and handed within the request header. This key shall be utilized by the server to make sure that repeated calls to the identical motion technique is not going to create duplicate information within the database. In different phrases, if the hot button is already current within the KeyStore, then the request for creation of the useful resource shall be ignored. The presence of the important thing within the KeyStore signifies that the request was already processed earlier.

Takeaways

By embracing idempotency, you may construct APIs which might be sturdy, dependable, and fault-tolerant. Idempotent APIs are significantly essential and useful in distributed techniques, the place community points would possibly result in giant numbers of retried requests from the consumer facet. That stated, it’s best to all the time validate enter knowledge to make sure knowledge consistency earlier than storing knowledge within the database.