(Please Select), Smith, Bob Jones, Sue .. how remove comma after (Please Select) in LINQ?

  • Thread starter Thread starter Ronald S. Cook
  • Start date Start date
R

Ronald S. Cook

Hey guys,

The below code works fine, BUT appends a comma to my (Please Select).
Anybody know how I can get around this?

Thanks... and sorry is in VB.NET (I wish I was in C# on this project)... but
you guys are WAY more helpful than the VB forum.

Dim _Query As IEnumerable(Of Employee) = _
From e In dc.Employees _
Where e.Lookup.LookupCode <> "INA" _
Order By e.EmployeeLastName, _
e.EmployeeFirstName

Dim _Employee As New Employee()
_Employee.EmployeeLastName = "(Please Select)"
_Employee.EmployeeFirstName = ""
Dim _List As IList(Of Employee) = _Query.ToList()
_List.Insert(0, _Employee)

Dim _QueryWithSelect As IEnumerable = _
(From xyz In _List _
Select xyz.EmployeeId, _
EmployeeName = xyz.EmployeeLastName & ", " &
xyz.EmployeeFirstName).ToList()

Return _QueryWithSelect
 
Ronald S. Cook said:
The below code works fine, BUT appends a comma to my (Please Select).
Anybody know how I can get around this?
Click to expand...

Sure. Currently you've got the following steps:

1) Build database query
2) Execute query and store results in list
3) Insert extra entry in list
4) Project list to strings
5) Convert to list
6) Return

Put step 3 after step 5 instead.
 
Thanks John! And Sloan, I did try to first conver the code to C# but the
converters out there aren't up on converting LINQ yet.

Man, I sure wish this project was in C#... mostly for 1) nicer flow of
syntax, and 2) support resources out there... especially LINQ sample code!
 
I mean't "Jon" not "John"... sorry.


Jon Skeet said:
Sure. Currently you've got the following steps:

1) Build database query
2) Execute query and store results in list
3) Insert extra entry in list
4) Project list to strings
5) Convert to list
6) Return

Put step 3 after step 5 instead.
Click to expand...
 
Hi Jon.. sorry to bother one last time, but I think I did something wrong
with your re-ordering recommendation.

With the re-ording below, the list is returned, but doesn't contain the
(Please Select) record. Any last idea how to squeeze it in?

'1) Build database query.
Dim _Query As IEnumerable(Of Employee) = _
From e In dc.Employees _
Where e.Lookup.LookupCode <> "INA" _
Order By e.EmployeeLastName, _
e.EmployeeFirstName

'2) Execute query and store results in list.
Dim _List As IList(Of Employee) = _Query.ToList()

'4) Project list to strings.
'5) Convert to list.
Dim _QueryWithSelect As IEnumerable = _
(From xyz In _List _
Select xyz.EmployeeId, _
EmployeeName = xyz.EmployeeLastName & ", " & xyz.EmployeeFirstName).ToList()

'3) Insert extra entry in list.
Dim _Employee As New Employee()
_Employee.EmployeeLastName = "(Please Select)"
_Employee.EmployeeFirstName = ""
_List.Insert(0, _Employee)

'6) Return.
Return _QueryWithSelect

Thanks!
Ron
 
Hi Jon.. sorry to bother one last time, but I think I did something wrong
with your re-ordering recommendation.

With the re-ording below, the list is returned, but doesn't contain the
(Please Select) record. Any last idea how to squeeze it in?
Click to expand...

'3) Insert extra entry in list.
Dim _Employee As New Employee()
_Employee.EmployeeLastName = "(Please Select)"
_Employee.EmployeeFirstName = ""
_List.Insert(0, _Employee)
Click to expand...

Currently you're adding the dummy record into the intermediate list
*after* you've converted the list. You need to add it to the resulting
(string) list instead.

This bottom line should be

_QueryWithSelect.Insert(0, "(Please Select)")

and _QueryWithSelect should be declared as a List(Of String).

Jon
 
Thanks so much for the help, Jon. I made the changes you said (which make
sense), but then get this error:

Unable to cast object of type
'System.Collections.Generic.List'1[VB$AnonymousType_20'2[System.Guid,System]]'
to type System.Collections.Generic.IList'1[System.String]'.

Here is the code as I understand I should have it. I promise not to bother
you anymore!

'1) Build database query.
Dim _Query As IEnumerable(Of Employee) = _
From e In dc.Employees _
Where e.Lookup.LookupCode <> "INA" _
Order By e.EmployeeLastName, _
e.EmployeeFirstName

'2) Execute query and store results in list.
Dim _List As IList(Of Employee) = _Query.ToList()

'4) Project list to strings.
'5) Convert to list.
Dim _QueryWithSelect As IList(Of String) = _
(From xyz In _List _
Select xyz.EmployeeId, _
EmployeeName = xyz.EmployeeLastName & ", " & xyz.EmployeeFirstName).ToList()

'3) Insert extra entry in list.
_QueryWithSelect.Insert(0, "(Please Select)")

'6) Return.
Return _QueryWithSelect
 
Ronald S. Cook said:
Thanks so much for the help, Jon. I made the changes you said (which make
sense), but then get this error:

Unable to cast object of type
'System.Collections.Generic.List'1[VB$AnonymousType_20'2[System.Guid,System]]'
to type System.Collections.Generic.IList'1[System.String]'.

Here is the code as I understand I should have it. I promise not to bother
you anymore!
Click to expand...

Ah, sorry, with the VB syntax I hadn't noticed that the projection was
to an anonymous type.

You'll need to create another instance of that anonymous type for the
"Please Select" entry, and make _QueryWithSelect implicitly typed. I
don't know how to do that in VB, I'm afraid.
 
Jon said:
Ronald S. Cook said:
Thanks so much for the help, Jon. I made the changes you said
(which make sense), but then get this error:

Unable to cast object of type
'System.Collections.Generic.List'1[VB$AnonymousType_20'2[System.Guid,System]]'
to type System.Collections.Generic.IList'1[System.String]'.

Here is the code as I understand I should have it. I promise not to
bother you anymore!
Click to expand...

Ah, sorry, with the VB syntax I hadn't noticed that the projection was
to an anonymous type.

You'll need to create another instance of that anonymous type for the
"Please Select" entry, and make _QueryWithSelect implicitly typed. I
don't know how to do that in VB, I'm afraid.
Click to expand...

Or just use Array.ConvertAll instead of Linq. Is there a new extension
method that makes ConvertAll available for a List perhaps?
 
Ben Voigt said:
Or just use Array.ConvertAll instead of Linq. Is there a new extension
method that makes ConvertAll available for a List perhaps?
Click to expand...

List<T>.ConvertAll has been available since .NET 2.0. However, I don't
think that's the issue - the issue is adding the "(Please Select)"
*after* the projection to an anonymous type.
 
Jon Skeet said:
List<T>.ConvertAll has been available since .NET 2.0. However, I don't
think that's the issue - the issue is adding the "(Please Select)"
*after* the projection to an anonymous type.
Click to expand...

LINQ isn't helpful for the stringification, though, in this case.

IEnumerable<Employee> query = From e In dc.Employees Where
e.Lookup.LookupCode <> "INA" Order By e.EmployeeLastName,
e.EmployeeFirstName;
List<Employee> listEmp = New List<Employee>(query)
List<string> listStrings = listEmp.ConvertAll(e => e.EmployeeLastName + ", "
+ e.EmployeeFirstName);
listStrings.Insert(0, "(Please Select)");
 
Ben Voigt said:
LINQ isn't helpful for the stringification, though, in this case.

IEnumerable<Employee> query = From e In dc.Employees Where
e.Lookup.LookupCode <> "INA" Order By e.EmployeeLastName,
e.EmployeeFirstName;
List<Employee> listEmp = New List<Employee>(query)
Click to expand...

That's more simply done with ToList() if you really need a list - but
you don't, here.
List<string> listStrings = listEmp.ConvertAll(e => e.EmployeeLastName + ", "
+ e.EmployeeFirstName);
listStrings.Insert(0, "(Please Select)");
Click to expand...

But the point is that I was mistaken in my original assumption that
this was projecting to strings - it isn't. It's converting to a list of
anonymous type instances, which is why my original suggestion didn't
work.

However, if it *did* use strings, it could all be done without
ConvertAll:

var strings = Enumerable.Repeat("(Please Select)", 1)
.Concat(query.Select
(e => e.EmployeeLastName + ", " + e.EmployeeFirstName));
 
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