next code works with no problem at all but, isn't there a more elegant way?
What I want is to show all records when querystring is null and only those
who match the criteria when querystring is not null.
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The following code works well as long as I pass a querystring value to the datalist.
Private Sub BindGrid()
Dim id As Integer = Integer.Parse(Context.Request.QueryString("id"))
Dim strConnString As String = ConfigurationManager.ConnectionStrings("Conn").ConnectionString
Using con As New SqlConnection(strConnString)
Using cmd As New SqlCommand()
cmd.CommandText = "select Id, Name from tblFiles where Id=@Id"
[Code] ......
However, the page errors with the message "Value cannot be null." if I don't pass a value. I know that DataList does not have an EmptyItem Property like a Gridview control. I do not want the page to error if I don't pass a value. Need info to deal with empty values in a datalist.
Most websites have pointed me to this code to use:
<FooterTemplate>
<asp:Label ID="lblEmpty" Text="No Result" runat="server"
Visible='<%#boolean.parse(([b]list[/b].Items.Count=0).ToString())%>'>
</asp:Label>
</FooterTemplate>
The 'list' throws an error. The error is "Too few type arguments to 'System.COllections.Generic.List". I am not sure if the code is written in C# and that is what is causing the error. It seems that it should work but I can not figure out the 'list' error.
specify a querystring to be always null when there is no value to pass?I always get an error saying NULL can't be converted to INT.The SQL datatype for this querystring is int.
View 5 RepliesHow to check the query string value null, if null then display the default value instead of object reference error.
View 1 RepliesI m using multiple sitemaps in my website. The providers are defined in web.config file as:
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Now I m trying to modify one of my xml file in memory to dynamically populate querystring but when I use
Dim currentNode
As
SiteMapNode =
SiteMap.CurrentNode.Clone(True)
I get Null in my currentNode and I cant point to the node.
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I have to get the maximum of these two select values. The select values are nullable. How do I go about checking if the value is null before calling the Max() method on it? I tried the ?? coalesing operator (example: e.HomeSales.Max() ?? 0M,) but I get the following error:"Operator '??' cannot be applied to operands of type 'decimal' and 'decimal'"
I have a class library which has my LINQ doc in it. I added a stored procedure and I get the following in my .dbml.layout :
[Code]....
I include a reference to the dll of the class library to my web project and I get an error about value being returned as int where I am trying to put contents into a datalist or similar.
Code in class that calls this SP :
[Code]....
So I switched code to the following in my dbml.layout document :
[Function(Name="dbo.sp_newsSearch")]public IEnumerable<news_search_result> sp_newsSearch([Parameter(DbType="VarChar(200)")] string searchVal){IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), searchVal);return ((IEnumerable<news_search_result>)(result.ReturnValue));}
And included the following in an external file news_search_result.cs
[Code]....
But now I just get nothing returned. Is this wrong way of calling a SP via LINQ? or have I just put the wrong return type on my LINQ class?
(This is a more narrow question)
In my asp.net MVC action, I am looking if the ReturnUrl value is in the URL.
My Url looks like this:
[URL]
In my action, I am looking if that querystring value exists, and it is returning NULL?? How can this be?
The code:
if(Request.QueryString["ReturnUrl"] != null)
{
}
Tracing through the application, it is just skipping the if statement's body i.e. it is NULL.
How can this be explained?
[URL]
I have a requirement to convert LINQ to DataTable.
I stole the following Extension Method from StackOverflow:
[code]....
I have a linq to sql entity class in which I declared some DateTime fileds like this:
[Code]....
And this is how I fetch data form repository:
[Code]....
All non DateTime fields are filled properly but all datetimes are null.[Column(DbType = "smalldatetime")]
I'm having a spot of trouble figure out how to write my linq query so that is allows a decimal field in my datatable to be null
Right now I have this:
[Code]....
But it's not working. The error I am getting is: Cannot cast DBNull.Value to type 'System.Decimal'. Please use a nullable type.so how do I get it to allow program_ar_id to be null?
Right now I have an error if f.ParentID is null:
DataSet1.TreeItemRow[]
TreeItemRows = (from f
in tidt
where (f.ParentID == TreeItemId)
select f).ToArray();
I must continue if f.ParentID is null, I don't want to include null fileds in the array. What is the right syntax for that is linq sql?
I am converting my datatable to LISt using LINQ how do I handle nulls coming from database
List<Port> portDetails = new List<Port>();
DataTable dt = ds.Tables[0];
portDetails = (from q in dt.AsEnumerable()
select new Port
{
PortCode = q.Field<string>("Code"),
ExtCode = q.Field<string>("Nb"),
Name = q.Field<string>("Name"))
}).ToList();
In the above query if Code is null I do not want property portcode to be set to the value it should only set if it is not null or not blank
PortCode = q.Field<string>("Code"),
What should be syntax
I was trying somethign like this which doesnt work
Portcode = q.Field<bool>("Code") == null ? null : q.Field<bool>("Code")
I have a SP db.sp_GetProfitMatrix , it takes nullable integer parameters, for which I have a default . It refuses me when I try to pass a null value (the two date parameters are nullable in the Linq designer) I get {"Nullable object must have a value."} error. here is my code:
int? nlDt = null;
var pms =
from p
in db.sp_GetProfitMatrix( nlDt.Value, nlDt.Value)
select
new
{
p.Volume,
p.GrossSales,
p.NetSales,
p.COGS
};
Using linq to entities i am connecting to a database, the database has tables in it that has payments that have a multi to multi relationship with jobs. This is acheived via an allocs table. I want a list box with all the jobs that has a column called due price which takes all of the allocations of payments for this job and takes that away from the job price. However, using the below linq to entities statement. The problem is that if the job has no allocations it returns null and therefore the due payment is empty. What i really want is for the due payment to be the job price if there are no allocations however, i cannot think of a way around this.
var jobs = from j in data.jobs
where j.property.customer.id == customerid
&& j.completed != null
select new
{
j.id,
j.price,
dueprice = j.price - ( from a in data.allocs
where a.job.id == j.id
select a.amount ).Sum(),
lineone = j.property.lineone,
postcode = j.property.postcode,
jobtype = j.jobtype.name,
j.completed
};
I'm using LINQ together with XDocument to read a XML File. This is the code:XDocument xml = XDocument.Load(filename);
var q = from b in xml.Descendants("product")
select new
{
[code]...
How to make the linq throw error, when not null columns are there in the table.
Why I am saying, it is. I tried to add to column in the table. Linq throwed error os some sort. I could not understand. it was like some innner table etc.
I had to resort to native sql, which showed the error, as the not null fields are there in the table.
How can i use querystring for this-
Here in below code i have used querystring for sending imagename from this page to another page. Now i just want that with this imagename in also want to send span element's text with same querystring.How can i achieve this?
[Code]....
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this code give that solution.but if any one of the field have null(example:r.urrQuickLinkRights contain the NULL) then only it will throw error like Object reference not set to an instance of an object.
In this code snippet:
using (DataClassesDataContext myContext = new DataClassesDataContext())
{
var myEvents = (from ev in myContext.Events [code].....
So I'm thinking there must be something about the Event object that has been created for me that is causing the problem...?S
I'm intermittently seeing this exception being thrown:
A potentially dangerous Request.QueryString value detected
However when I look in the IIS logs I can see that the request that failed has no querystring logged against it.
How could this be? Are "dangerous" query strings being stripped from the log or something?
Encrypt request.querystring and Descrpt request.querystring
View 1 RepliesI have setup my business object to have a create_date and edit_date members both datetime datatypes. My company want to display the create_date and edit_date fields in a gridview for each transaction. The problem i have is that after insterting a record it will have a valid create_date but no edit_date and when displayed in the gridview it defaults to datetime.minvalue (My default). How on earth do i show an empty field in my gridview for a null datetime field in the database?
I am using similar architecture to the Imar Spaanjaars example of a tiered solution. With a few small tweeks it has worked well for me for ages. I am passing a List<Database> to my object datasource which connects to my gridview.
I have 2 table Table A, Table B.
Table A - Parent Table
ID - Uniqueidentifier not null(PK)
Table B -Child Table
ID - uniqueidentifier null(FK, TableA)
I have a stored procedure to insert data into Table B, but when I tried to insert a null value into column ID of table B, this error came up:
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tableB_tableA". The conflict occurred in database "database name", table "table A", column 'ID'.
The statement has been terminated.
The insert statement in asp.net is like so:
sqlcommand.parameter.add(New Sqlparameter("ID", Nothing))
I am guessing adding nothing to the null value column is the problem, but i don't know how to fix it... The INSERT statement conflicted with the FOREIGN KEY constraint "FK_tableB_tableA". The conflict occurred in database "database name", table "table A", column 'ID'.
I have a problem with a SessionVariable. I will explain what is happening:
1. From the default.aspx I send Session["LoginByAdmin"] = "Dummy"; and then redirect to this page where I have the code below. So the Page_Load sees that this Session["LoginByAdmin"] != null and enter this page. This works fine !
2. In the Page_Load, I later fill a ListBox1 with foldernames.
3. With Button1_Click1, I will now delete the choosen Folder in the ListBox1 wich works fine the first time and the ListBox updates the new existing folders in the ListBox. (I have wrapped this inside an updatepanel)
The problems comes now when I try to delete a choosen folder in the ListBox1 the second time in a row. When I select a Folder in the ListBox1 and now Press Button1, I will be redirected to "Default.aspx". This meens that this code is running: (That meens that Session["LoginByAdmin"] == null and I have not set this to null anywhere. This is my big question how this variable can be = null here?
if (Session["LoginByAdmin"] == null)
Response.Redirect("Default.aspx");
break;
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