Develop Reference

What value should I return in catch?

I just implemented a Try catch in my code, the error is because I have to return something in the catch,
I can't understand is "what should I return?"
'CompanyController.Create(DtoCompany)': not all code paths return a
value [API]
[HttpPost("create/")]
public async Task<ActionResult> Create([FromBody] DtoCompany dto_company)
{
try
{
var query = context.Companies.FirstOrDefault(x => x.rnc == dto_company.rnc);
if (query != null)
{
Company comp = mapper.Map<Company>(query);
context.Add(comp);
await context.SaveChangesAsync();
return Ok("Registro de compania exitoso");
}
else
{
return BadRequest($"Ya existe una compañia con este RNC: `{dto_company.rnc}`");
}
}
catch (Exception ex)
{
Console.WriteLine("Error From Company-Create:", ex.Message);
}
}
If I write the return this, I getting an other error:
catch (Exception ex)
{
return Console.WriteLine("Error From Company-Create:", ex.Message);
}
Cannot implicitly convert type 'void' to
'Microsoft.AspNetCore.Mvc.ActionResult' [API]

You should return an error telling your client what went wrong.
A good way to to this is to return Problem().
https://learn.microsoft.com/en-us/aspnet/core/web-api/handle-errors?view=aspnetcore-6.0

'CompanyController.Create(DtoCompany)': not all code paths return a
value [API]
I can't understand is "what should I return?"
If in the try block there's already a return statement, you could put the other return at the end of the function, and this in order to avoid multiple returns if multiple exceptions need to be handled:
try
{
//somecode
return Ok();
}
catch(Exception ex)
{
Console.WriteLine("Error From Company-Create:", ex.Message);
}
return BadRequest();// add this code

You shouldn't return anything from the catch part just a MessageBox or Console.WriteLine which you implemented on the first block...
Simply try catch statement is to ask compiler to do something and if any error occurred in the code simply catch it and show it me using a MessageBox or Console.WriteLine
Example:
try
{
sqlConnection conn = new sqlConnection(connection_string);
conn.Open();
}
catch (Exception ex)
{
if (ex.Message == "Certain specific error")
MessageBox.Show("Do not do it");
else
MessageBox.Show("Please do not do it");

Get EventMessage from message in MS Graph API with C#

I am trying to Get EventMessage from Message in MS Graph API with C# but every time it is showing type as a message instead of EventMessage. Below are the code:-
public static Graph.MailFolderMessagesCollectionPage ReadInbox()
{
GetAuthenticatedClient();
var result = new Graph.MailFolderMessagesCollectionPage();
List<Graph.QueryOption> options = new List<Graph.QueryOption>
{
new Graph.QueryOption("$expand","microsoft.graph.eventMessage/event"),
new Graph.QueryOption("$filter","isread eq false")
};
try
{
var response = graphClient.Me.MailFolders.Inbox.Messages.Request(options).OrderBy("receivedDateTime DESC").GetAsync();
result = response.Result as Graph.MailFolderMessagesCollectionPage;
}
catch (Exception ex)
{ }
Call the above method ReadInbox to get type and perform some action.
var appointments = ReadInbox();
if (appointments != null)
{
foreach (dynamic request in appointments)
{
try
{
if (request.GetType().Name.Contains("EventMessage"))
{
}
else if (request.GetType().Name == "Message")
{
}
}
catch (Exception ex)
{
}
}
}

Use the IsInstanceOfType method to identify if its an eventMessage. You can also remove the expand option from the query option since eventMessages are fetched anyway as part of the get Messages call.
if (appointments != null)
{
foreach (dynamic request in appointments)
{
try
{
if (typeof(EventMessage).IsInstanceOfType(request))
{
Console.WriteLine("Is an event");
Console.WriteLine(request);
}
}
catch (Exception ex)
{
}
}
}

Overriding SaveChangesAsync when enclosed inside TransactionScope?

I'm fairly new to EF transactions, this is the code that is used for saving
public bool Save(TbArea area, bool isNew, out string errMsg)
{
try
{
errMsg = string.Empty;
using (var oScope = new System.Transactions.TransactionScope(TransactionScopeOption.Required, TimeSpan.FromSeconds(120)))
{
try
{
TbArea oEntity = oContext.TbArea.Where(a => a.AreaCode == area.AreaCode && a.CompanyId == MainClass.SystemCompanyId).FirstOrDefault();
if (oEntity != null)
{
if (isNew) { errMsg = Resources.ResSales.MsgRecordCodeDublicated; return false; }
oContext.TbArea.Attach(oEntity);
oContext.Entry(oEntity).CurrentValues.SetValues(area);
}
else
{
if (!isNew) { errMsg = Resources.ResSales.MsgRecordNotFoundInDB; return false; }
oContext.TbArea.Add(area);
}
oContext.SaveChangesAsync();
oScope.Complete();
return true;
}
catch (Exception ex)
{
oScope.Dispose();
errMsg = ex.Message;
return false;
}
}
I'm overriding SaveChangesAsync
so that I can save the ChangeTracker.Entries into the database.
this is a portion of the code:
dbContext.AcceptAllChanges();
logsSet.AddRange(audits);
int result = 0;
try
{
result = await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
//scope.Complete(); there was a transaction that I commented out, I thought it might overlaps the original transaction!
return result;
}
catch (Exception ex)
{
var m = ex.Message;
return result;
}
When I save an item, I get the error :
the transaction has aborted
when I remove the transaction scope the saving happens normally!

Your code is marking the transaction complete before the changes have finished saving:
oContext.SaveChangesAsync();
oScope.Complete();
You need to use await:
await oContext.SaveChangesAsync();
oScope.Complete();
If you're in a context where await can resume on a different thread, you'll probably also need to specify TransactionScopeAsyncFlowOption.Enabled.

Error Trapping Best Method

Hi I am trying to get a list of all trouble tickets but it says that not all codes paths return a value. Does Anybody no what I am doing wrong thanks
public List<TroubleTicket> GetAllTroubleTickets()
{
try
{
List<TroubleTicket> tickets = new List<TroubleTicket>();
var q = _supportDeskEntities.TroubleTickets.ToList();
return q;
}
catch (Exception ex)
{
}
}

If you catch an exception the function returns no value. So change this:
catch (Exception ex)
{
}
To this:
catch (Exception ex)
{
return null;
}
Or if you want it to return an empty list when an exception is catch then you can do this:
catch (Exception ex)
{
return new List<TroubleTicket>(0);
}
If we are taking about best practice then I would say that you should log the exception and then re-throw it. Like this:
catch (Exception ex)
{
//write to log
throw ex;
}

You need to return a value from the catch statement (or throw another exception within it). Otherwise, the function will return null
You can try this:
public List<TroubleTicket> GetAllTroubleTickets()
{
try
{
List<TroubleTicket> tickets = new List<TroubleTicket>();
var q = _supportDeskEntities.TroubleTickets.ToList();
return q;
}
catch (Exception ex)
{
return new List<TroubleTicket>(); // This is just in case you want to ignore any exceptions
}
}
or
catch (Exception ex)
{
throw new Exception("There was an error getting tickets"); // Probably not as good of a way as you lose the exception details
}

You only return a value if there is no exception thrown. You must either return from inside the catch block, or return outside the try/catch structure.
So you can either return in two separate places:
public List<TroubleTicket> GetAllTroubleTickets()
{
try
{
var q = _supportDeskEntities.TroubleTickets.ToList();
return q;
}
catch (Exception ex)
{
// You can also return "new List<TroubleTicket>()" if null is an unacceptable return value
return null;
}
}
or keep a return value variable, and set it in two different locations, and return it in one location:
public List<TroubleTicket> GetAllTroubleTickets()
{
List<TroubleTicket> tickets;
try
{
tickets = _supportDeskEntities.TroubleTickets.ToList();
}
catch (Exception ex)
{
// You can also use "new List<TroubleTicket>()" if null is an unacceptable return value
tickets = null;
}
return tickets;
}

You're not returning anything if an exception happens and you're not assigning the list to List<TroubleTicket> tickets but to a different variable. You could do:
public List<TroubleTicket> GetAllTroubleTickets()
{
List<TroubleTicket> tickets = null;
bool gotTickets = true;
try{
tickets = _supportDeskEntities.TroubleTickets.ToList();
}
catch (SpecificException ex){
gotTickets = false;
}
catch (Exception ex){ // catches all other "unexpected" exceptions
// log and/or...
throw;
}
return gotTickets ? tickets : null;
}
But you should not catch all kind of exceptions but only specific types that you expect. You also should log all other types of exceptions.

Your catch block is not returning anything.
public List<TroubleTicket> GetAllTroubleTickets()
{
List<TroubleTicket> tickets =null;
try
{
tickets = new List<TroubleTicket>();
var q = _supportDeskEntities.TroubleTickets.ToList();
return q;
}
catch (Exception ex)
{
//Log or handle your error
}
return tickets;
}

What's wrong with this function. unable to return string value

public static string GetContentFromSPList(string cValueToFind)
{
string cValueFound = "";
try
{
SPSecurity.RunWithElevatedPrivileges(delegate()
{
using (SPSite site = new SPSite("http://mysite"))
{
site.AllowUnsafeUpdates = true;
using (SPWeb web = site.OpenWeb())
{
web.AllowUnsafeUpdates = true;
SPList oListAbout = web.Lists["About"];
SPQuery oQuery = new SPQuery();
oQuery.Query = "<OrderBy><FieldRef Name='myField' /></OrderBy><Where><Eq><FieldRef Name='myField' /><Value Type='Choice'>" + cValueToFind + "</Value></Eq></Where>";
SPListItemCollection collListItems = oListAbout.GetItems(oQuery);
foreach (SPListItem oListItem in collListItems)
{
cValueFound = (oListItem["FieldContents"] != null ? oListItem["FieldContents"].ToString() : "");
}
}
}
return cValueFound;
});
//return cValueFound;
}
catch (Exception ex)
{
}
finally
{
//return cValueFound;
}
}
Above is the piece of code.
Problem is not allowing to return the string. It keeps on giving compilation errors. I am sure I am doing something wrong!!.
Thanks.

I suppose it's something like:
"not all codes return value".
If so, just add
public static string GetContentFromSPList(string cValueToFind)
{
string cValueFound = "";
try
{
//code
}
catch (Exception ex)
{
}
finally
{
//some cleanup
}
return cValueFound ;
}

Put this at the bottom of your method because you don't return if an exception is caught.
catch (Exception ex)
{
return cValueFound;
}
finally
{
}
}

You cannot return from finally,
(control cannot leave the body from finally clause or something)
move the return either after finally or from catch

just add your return statement below finally block.
Dont return in try blck.

I have seen developers missing this lot of times. Reason this happens is because once you define the return type of a function, then function should have a return statement at all exit points. In this case a function should have a return statement one at the end of the try block and one inside a catch block or just one right at the bottom as Tigran has defined. If you do not intend to return any thing from the catch block then just return null;
public static string GetContentFromSPList(string cValueToFind)
{
string value= "";
try
{
//code
return value;
}
catch (Exception ex)
{
return null;
}
finally
{
//some cleanup
}
}