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dotnet ado.net : Null Dates in Dataset
more rows. At least one of the columns is a date and it may null. I have created an XSD of the output from the stored proc. The entry for the nullable date column is "<xs:element name="Sent_Dttm" minOccurs="0" type="xs:dateTime" nillable="true"></xs:element>". I copied the XSD to the C# 2.0 windows app I am developing and it nicely generates a strongly typed dataset. The problem is I get an error when attempting to access this column in the dataset when the value is null: [System.Diagnostics.DebuggerNonUserCodeAttribute()] public System.DateTime Sent_Dttm { get { try { return ((System.DateTime)(this[this.tableOwizCommDoc.Sent_DttmColumn])); } catch (System.InvalidCastException e) { throw new System.Data.StrongTypingException("The value for column \'Sent_Dttm\' in table \'OwizCommDoc\' is DBNull.", e); } } set { this[this.tableOwizCommDoc.Sent_DttmColumn] = value; } } Checking the properties of this field, I noticed that the "NullValue" property has a value of "(throw exception)'
The issue is that I'm getting bounced in a section of the code automatically
generated when I add an XSD file to the project. If I start going in and changing generated code than I am defeating the advance of the code generation. I was hoping that there was a way of influencing the code generation. Is there? [quoted text, click to view] "Jim Rand" wrote:
> This is by design. The strongly typed dataset will have a method (not > property) IsSent_DttmNull() if the underlying column can be null. > > if (!IsSent_DttmNull) {access the value} > > "Rachel Appel" <none@example.com> wrote in message > news:MPG.218ac7a7b92c306989680@msnews.microsoft.com... > > In article <F82909CD-DEBB-457A-AC69-DED1C4D72BE5@microsoft.com>, > > RobertEFlaherty@discussions.microsoft.com says... > >> Using C# 2.0 & SQL Server 2000, have a stored procedure that return 0, 1, > >> or > >> more rows. At least one of the columns is a date and it may null. I > >> have > >> created an XSD of the output from the stored proc. The entry for the > >> nullable date column is "<xs:element name="Sent_Dttm" minOccurs="0" > >> type="xs:dateTime" nillable="true"></xs:element>". I copied the XSD to > >> the > >> C# 2.0 windows app I am developing and it nicely generates a strongly > >> typed > >> dataset. > >> > >> The problem is I get an error when attempting to access this column in > >> the > >> dataset when the value is null: > >> [System.Diagnostics.DebuggerNonUserCodeAttribute()] > >> public System.DateTime Sent_Dttm { > >> get { > >> try { > >> return > >> ((System.DateTime)(this[this.tableOwizCommDoc.Sent_DttmColumn])); > >> } > >> catch (System.InvalidCastException e) { > >> throw new System.Data.StrongTypingException("The > >> value for column \'Sent_Dttm\' in table \'OwizCommDoc\' is DBNull.", e); > >> } > >> } > >> set { > >> this[this.tableOwizCommDoc.Sent_DttmColumn] = value; > >> } > >> } > >> > >> > >> Checking the properties of this field, I noticed that the "NullValue" > >> property has a value of "(throw exception)' > >> > >> > >> > >> > > > > Robert, > > Try checking for System.DbNull before accessing the variable and that > > should help you out. > >
In article <F82909CD-DEBB-457A-AC69-DED1C4D72BE5@microsoft.com>,
RobertEFlaherty@discussions.microsoft.com says... [quoted text, click to view] > Using C# 2.0 & SQL Server 2000, have a stored procedure that return 0, 1, or > more rows. At least one of the columns is a date and it may null. I have > created an XSD of the output from the stored proc. The entry for the > nullable date column is "<xs:element name="Sent_Dttm" minOccurs="0" > type="xs:dateTime" nillable="true"></xs:element>". I copied the XSD to the > C# 2.0 windows app I am developing and it nicely generates a strongly typed > dataset. > > The problem is I get an error when attempting to access this column in the > dataset when the value is null: > [System.Diagnostics.DebuggerNonUserCodeAttribute()] > public System.DateTime Sent_Dttm { > get { > try { > return > ((System.DateTime)(this[this.tableOwizCommDoc.Sent_DttmColumn])); > } > catch (System.InvalidCastException e) { > throw new System.Data.StrongTypingException("The > value for column \'Sent_Dttm\' in table \'OwizCommDoc\' is DBNull.", e); > } > } > set { > this[this.tableOwizCommDoc.Sent_DttmColumn] = value; > } > } > > > Checking the properties of this field, I noticed that the "NullValue" > property has a value of "(throw exception)' > > > > Robert, Try checking for System.DbNull before accessing the variable and that
This is by design. The strongly typed dataset will have a method (not
property) IsSent_DttmNull() if the underlying column can be null. if (!IsSent_DttmNull) {access the value} [quoted text, click to view] "Rachel Appel" <none@example.com> wrote in message news:MPG.218ac7a7b92c306989680@msnews.microsoft.com... > In article <F82909CD-DEBB-457A-AC69-DED1C4D72BE5@microsoft.com>, > RobertEFlaherty@discussions.microsoft.com says... >> Using C# 2.0 & SQL Server 2000, have a stored procedure that return 0, 1, >> or >> more rows. At least one of the columns is a date and it may null. I >> have >> created an XSD of the output from the stored proc. The entry for the >> nullable date column is "<xs:element name="Sent_Dttm" minOccurs="0" >> type="xs:dateTime" nillable="true"></xs:element>". I copied the XSD to >> the >> C# 2.0 windows app I am developing and it nicely generates a strongly >> typed >> dataset. >> >> The problem is I get an error when attempting to access this column in >> the >> dataset when the value is null: >> [System.Diagnostics.DebuggerNonUserCodeAttribute()] >> public System.DateTime Sent_Dttm { >> get { >> try { >> return >> ((System.DateTime)(this[this.tableOwizCommDoc.Sent_DttmColumn])); >> } >> catch (System.InvalidCastException e) { >> throw new System.Data.StrongTypingException("The >> value for column \'Sent_Dttm\' in table \'OwizCommDoc\' is DBNull.", e); >> } >> } >> set { >> this[this.tableOwizCommDoc.Sent_DttmColumn] = value; >> } >> } >> >> >> Checking the properties of this field, I noticed that the "NullValue" >> property has a value of "(throw exception)' >> >> >> >> > > Robert, > Try checking for System.DbNull before accessing the variable and that > should help you out.
As I pointed out earlier, the error is occurring in code generated when I
copied an XSD file to my C# 2.0 project. The line of code that I manually generated is "ds.Load(rdr, LoadOption.OverwriteChanges, new String[] { "OwizCommFaxDoc" });" where ds has been defined as an instance of the strongly typed dataset. The line from the XSD that defines the offending column is "<xs:element name="Sent_Dttm" minOccurs="0" type="xs:dateTime" nillable="true"></xs:element> " minOccurs="1" type="xs:string"></xs:element> [quoted text, click to view] "Cor Ligthert[MVP]" wrote:
> Robert, > > If a column allows nulls, then there is in your strongly typed dataset > created a method named as IsTheFieldNameNull() > > If the DataBase does not allows Nulls, then it is of course a normal error. > > Cor
Robert,
If a column allows nulls, then there is in your strongly typed dataset created a method named as IsTheFieldNameNull() If the DataBase does not allows Nulls, then it is of course a normal error. Cor
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