ASP.NET Web API An error has occurred

Question

I am working on an ASP.NET Web API, and when I run this method, I get this error An error has occurred.

public List<DeviceClass> CheckDevice(string device) { devices = new List<DeviceClass>(); using( connection = new SqlConnection(connectionString)) { using (SqlCommand command = new SqlCommand("uspCheckDeviceID", connection)) { command.CommandType = CommandType.StoredProcedure; command.Parameters.Add("@sp", SqlDbType.VarChar).Value = device; connection.Open(); using (SqlDataReader reader = command.ExecuteReader()) { if(reader.HasRows) { if(reader.Read()) { DeviceClass model = new DeviceClass(); model.DeviceId = reader.GetValue(0).ToString(); model.Name = reader.GetValue(1).ToString(); model.Owner = reader.GetValue(2).ToString(); devices.Add(model); } } connection.Close(); } } } return devices; } 

What I'm trying to determine if its code or its connection to the server.

This is a stored procedure in which I gave an example:

 declare @sp varchar(30) set @sp ='marksiphoneid' exec uspCheckDeviceID @sp 

Is there something wrong with the way I am trying to get the results from my stored procedure?

Error

Failed to load the resource: the server responded with a status of 500 (Internal server error)

Answer 1

Include your method as follows:

 public HttpResponseMessage CheckDevice(string device) { try { devices = new List<DeviceClass>(); using (connection = new SqlConnection(connectionString)) { using (SqlCommand command = new SqlCommand("uspCheckDeviceID", connection)) { command.CommandType = CommandType.StoredProcedure; command.Parameters.Add("@sp", SqlDbType.VarChar).Value = device; connection.Open(); using (SqlDataReader reader = command.ExecuteReader()) { if (reader.HasRows) { if (reader.Read()) { DeviceClass model = new DeviceClass(); model.DeviceId = reader.GetValue(0).ToString(); model.Name = reader.GetValue(1).ToString(); model.Owner = reader.GetValue(2).ToString(); devices.Add(model); } } connection.Close(); } } } return Request.CreateResponse(HttpStatusCode.OK, devices.ToList()); } catch (Exception e) { //Request.CreateErrorResponse can do the same thing var err = new HttpRequestMessage(). CreateErrorResponse(HttpStatusCode.InternalServerError, e.ToString()); return new HttpResponseException(err); } } 

You can then get your Exception ToString when an error occurs.

To make sure you see the exception message, you can use Fiddler or PostMan . To test your API.

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Also, I just try the way in the commentary on the OP question,

In my case, I am testing the return of some exception object defined by me,

initially, when I call this GET method by entering the URL in Google Chrome,

Chrome just gives me a meaningless message An error has occured ,

and after adding

 GlobalConfiguration.Configuration.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always; 

with Global.asax.cs in the protected void Application_Start() method,

My Exceptional Object is displayed correctly.

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In an hour, I will find out that this could also be done in WebApiConfig.cs in the public static void Register(HttpConfiguration config) method on

 config.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always; 

Answer 2

An error of 500 means that you have an internal error in your service. It can be everything inside.

For example, your reader.GetValue (1) returns null. So you will have a null error and your server will return 500.