Web APIs methods with Warnings - asp.net

Question

I have this method in an API that does POST for creating a record, but before inserting that record in DB there are some validations that i must do, I might come back with warnings and I need to return back these warnings to the client to confirm back.
what is the best way to do that in Web API's? or should i split the method into 2, one for validation and one for saving?

Answer 1

Set up your Web Api the following way.
[HttpPost]
public IHttpActionResult DoStuff(object item)
{
if(!validate(item))
{
return this.BadRequest("Validation failed blablabla");
}
else
{
//insert logic
}
return this.Ok();
}
What happens is you validate the object you send to the API. When it fails to validate you return the request was not correct, with the message you specified.
When the validation succeeds the insert logic is called and you return a OK result when it succeeds.

Answer 2

I create and use a wrapper which would contain object to be bound to ui, messages (error or validation or warning) and total.
/// <summary>
/// Class for the Repository response object
/// </summary>
/// <typeparam name="T"></typeparam>
public class CLSResponse<T>
{
/// <summary>
/// Gets or sets the messages to be returned in the response.
/// </summary>
/// <value>The messages.</value>
public IEnumerable<KeyValuePair<string, string>> Messages {
get { return m_Messages; }
set { m_Messages = value; }
}
private IEnumerable<KeyValuePair<string, string>> m_Messages;
/// <summary>
/// Gets or sets the service model to be returned in the response.
/// </summary>
/// <value>The service model.</value>
public T ServiceModel {
get { return m_ServiceModel; }
set { m_ServiceModel = value; }
}
private T m_ServiceModel;
/// <summary>
/// Gets or sets the totalitems.
/// </summary>
/// <value>The TotalItems.</value>
public int TotalItems {
get { return m_TotalItems; }
set { m_TotalItems = value; }
}
private int m_TotalItems;
/// <summary>
/// Gets and Sets the Message Type based on the MessageType Struct
/// </summary>
public string MessagesType;
}
/// <summary>
/// Struct for MessageTypes to be returned with messages, in the response object
/// </summary>
public struct MessagesType
{
/// <summary>
/// Validation
/// </summary>
public static string Validation = "Validation";
/// <summary>
/// Warning
/// </summary>
public static string Warning = "Warning";
/// <summary>
/// Error
/// </summary>
public static string Error = "Error";
/// <summary>
/// Unauthorized
/// </summary>
public static string UnAuthorized = "Unauthorized";
}
Then in your repository layer or logic layer
public CLSResponse<bool> CreateUser(string request)
{
var messages = new List<KeyValuePair<string, string>>();
try
{
//Do something
if (!validation)
{
messages.Add(MessagesType.Validation, "Invalid");
return new CLSResponse<bool> {
ServiceModel = false,
Messages = messages,
MessagesType = MessagesType.Validation
};
}
else {
return new CLSResponse<bool> {
ServiceModel = true,
Messages = messages,
MessagesType = MessagesType.Error
};
}
}
catch (Exception ex)
{
messages.Add(MessagesType.Error, "UpdateFailed");
return new CLSResponse<bool> {
ServiceModel = false,
Messages = messages,
MessagesType = MessagesType.Error
};
}
}
Now on controller,
[HttpPost]
public HttpResponseMessage<CLSResponse<bool>> CreateUser(string input)
{
var res = LogicLayer.CreateUser(input);
//Check for res.MessageType and set the status code
if (res.MessagesType = MessagesType.Validation)
{
return Request.CreateResponse<CLSResponse<bool>>(HttpStatusCode.PreconditionFailed, res);
}
}
This way your response object still has the warning you added in logic layer and depending on the status code returned, you can handle those messages on client side.