Consume Dataset from Webservice

  • Thread starter Thread starter mikemc
  • Start date Start date
M

mikemc

I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db. When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3) If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals) appears to
work fine in the Watch window and there are no exceptions
thrown.

Can anybody help me please?

Thanks. Mike
 
Here is what I changed to Alex (I hardcoded the problem
column reference and changed my webservice to only return
the problem record):

If dr(3) Is DBNull.Value Then

which evaluates to False when I step through -- but the
watch window evaluates this to True.

Any thoughts?

-----Original Message-----
Compare to DBNull.Value instead

mikemc said:
I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db. When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3) If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals) appears to
work fine in the Watch window and there are no exceptions
thrown.

Can anybody help me please?

Thanks. Mike
Click to expand...


.
Click to expand...
 
How about Convert.IsDBNull(dr(3))?

mikemc said:
Here is what I changed to Alex (I hardcoded the problem
column reference and changed my webservice to only return
the problem record):

If dr(3) Is DBNull.Value Then

which evaluates to False when I step through -- but the
watch window evaluates this to True.

Any thoughts?

-----Original Message-----
Compare to DBNull.Value instead

mikemc said:
I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db. When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3) If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals) appears to
work fine in the Watch window and there are no exceptions
thrown.

Can anybody help me please?

Thanks. Mike
Click to expand...


.
Click to expand...
Click to expand...
 
That made a difference meaning that now the code and watch
window evaluate the same but the line:

If Convert.IsDBNull(dr(3)) = True Then

evaluates to false. That means that something exists but
I can't determine what. Please let me know if you think
of anything else -- and I will get back to you if I find
anything. Next steps are to compare against chr(0) and
maybe to start sniffing glue!

-----Original Message-----
How about Convert.IsDBNull(dr(3))?

mikemc said:
Here is what I changed to Alex (I hardcoded the problem
column reference and changed my webservice to only return
the problem record):

If dr(3) Is DBNull.Value Then

which evaluates to False when I step through -- but the
watch window evaluates this to True.

Any thoughts?

-----Original Message-----
Compare to DBNull.Value instead

I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db. When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3) If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals) appears to
work fine in the Watch window and there are no exceptions
thrown.

Can anybody help me please?

Thanks. Mike


.
Click to expand...
Click to expand...


.
Click to expand...
 
Why don't you simply set a breakpoint at that line and then in the Command
window enter:
dr(3) <enter>

That shoud tell you precisely what is in that field

mikemc said:
That made a difference meaning that now the code and watch
window evaluate the same but the line:

If Convert.IsDBNull(dr(3)) = True Then

evaluates to false. That means that something exists but
I can't determine what. Please let me know if you think
of anything else -- and I will get back to you if I find
anything. Next steps are to compare against chr(0) and
maybe to start sniffing glue!

-----Original Message-----
How about Convert.IsDBNull(dr(3))?

mikemc said:
Here is what I changed to Alex (I hardcoded the problem
column reference and changed my webservice to only return
the problem record):

If dr(3) Is DBNull.Value Then

which evaluates to False when I step through -- but the
watch window evaluates this to True.

Any thoughts?


-----Original Message-----
Compare to DBNull.Value instead

I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db.
When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3)
If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals) appears to
work fine in the Watch window and there are no
exceptions
thrown.

Can anybody help me please?

Thanks. Mike


.
Click to expand...


.
Click to expand...
Click to expand...
 
I did exactly like you said and got an error -- Command "dr
(3)" is not valid. Here is what ended up working:

If CType(dr(dc.Ordinal), String) = Chr(0) Then

I cannot say I know why -- maybe a ASCII vs. Unicode
problem? I am going to try the statement:

if dr(dc.Ordinal) = chr(0) then

just to remove the casting call if possible but I wanted
you to see this for your future reference. I have no idea
why I was unable to see this value -- if you have any
insight I would appreciate it.

Thanks so much for all your suggestions! If I can help
you in any way -- just remove the extra m from the email
on one of my earlier posts.

Thanks again!

Mike


-----Original Message-----
Why don't you simply set a breakpoint at that line and then in the Command
window enter:
dr(3) <enter>

That shoud tell you precisely what is in that field

That made a difference meaning that now the code and watch
window evaluate the same but the line:

If Convert.IsDBNull(dr(3)) = True Then

evaluates to false. That means that something exists but
I can't determine what. Please let me know if you think
of anything else -- and I will get back to you if I find
anything. Next steps are to compare against chr(0) and
maybe to start sniffing glue!

-----Original Message-----
How about Convert.IsDBNull(dr(3))?

Here is what I changed to Alex (I hardcoded the problem
column reference and changed my webservice to only return
the problem record):

If dr(3) Is DBNull.Value Then

which evaluates to False when I step through -- but the
watch window evaluates this to True.

Any thoughts?


-----Original Message-----
Compare to DBNull.Value instead

I am trying to consume a untyped dataset from a VB.NET
webservice and update a local SQL Server CE 2.0 db.
When
one of the values is null, I have been unable to
successfully test for it to build a SQL stmt.

I have tried: 1) If dr.IsNull(dc.Ordinal) Then, 2) If
dr.Item(dc.Ordinal).ToString.Trim.Length = 0 Then, 3)
If dr
(dc.Ordinal).ToString = "", and 4) If dr
(dc.Ordinal).ToString = [String].Empty where dr is the
datarow and dc is the datacolumn.

Every one of these statements (conditionals)
Click to expand...
appears
to
work fine in the Watch window and there are no
exceptions
thrown.

Can anybody help me please?

Thanks. Mike


.



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