I've written the following Extension Method
<Extension()>
Public Function ToUtcIso8601(ByVal dt As Date) As String
Return String.Format("{0:s}Z", dt)
End Function
But I also need a Nullable version of the same method... how exactly do I do this?
This is what I was thinking, but I'm not sure if this is the right way
[code]....
I have an ASMX Web Service set up to use the HTTP GET method. Simple methods which take basic String and Int parameters are working ok, and I can call MyService.asmx/MethodName?Param=Value and get a response back in XML.
However, when I have a method which has a nullable Int (i.e. int?), I get this error:
< Method Name > Web Service method name is not valid.
The error message is confusing, as the method does exist, just not in the GET scope. I presume this is because a nullable type is too complex to be passed via the URL, but I can't find any documentation or SO posts on this.
I appreciate that complex types like Lists or custom classes etc will not work using GET, but I would have assumed that a simple nullable int or nullable datetime could be handled natively, simply by detecting whether it was omitted from the URL. Guess it's not that simple!
I have a ASP.NET MVC view that displays a single ServiceProvider object. In this view there is a selectlist that lists one or more ServiceProviderGroup objects and uses the Id property for the value and the Name property for the text. In this list I also show a entry with a value of -1 and text of "No Provider". When the Edit[Post] method is called the Id value from the select list maps to a nullable property (GroupId) on a ServiceProvider object. When a value other the -1 is selected from the list it works as expected. But, when the value is -1, I want a NULL reference to be applied to the GroupId property during the UpdateModel call. Within the Edit method, prior to calling UpdateModel, I have tried replacing the entry within the Controller.ValueProvider with a null reference and adding a ValueProviderResult which contains a null reference, but the UpdateModel always has an issue (InvalidOperationException).
View 3 RepliesI have a property int? MyProperty as a member in my datasource (ObjectDataSource). Can I bind this to a TextBox, like
<asp:TextBox ID="MyTextBox" runat="server" Text='<%# Bind("MyProperty") %>' />
Basically I want to get a null value displayed as blank "" in the TextBox, and a number as a number. If the TextBox is blank MyProperty shall be set to null. If the TextBox has a number in it, MyProperty should be set to this number.If I try it I get an exception: "Blank is not a valid Int32".
But how can I do that? How to work with nullable properties and Bind?
I have a problem with passing a model to a controllerIn my controller I have a HttpPost function that gets a EF model.The problem is that the form does not contains all properties of the EF model.When the function is called that gets this EF model, I get error messge of fields that are not nullable in the EF model.That's because the fields are not in the form, so the not nullable properties gets no value.
View 5 RepliesI am a c#/asp.net developer and I am having to work on a VB/asp.net. I started out with VB.NET but after years away from it I'm getting confused with the syntax.
I have two variables
Dim originalDate as DateTime?
Dim newDate as DateTime?
Both nullable datetimes, originalDate is a nullable date I am getting from the database and newDate time is set in code, I need to compare them, they can either both have dates, neither have dates or one have and one not.
I have a bit of code as follows:
if origEndDate = origEndDate then
When both origEndDate and origEndDate are "nothing" this statement is false (well when I run it in the watch window it comes back as nothing)!
I don't understand why this is the case because I was under the impression doing an "=" compares the two values and as they are the same surely it should be true?
What syntax should I be using as in C# I can do the above as so:
if (origEndDate == origEndDate) { }
and it will come back as true.
I have a small Linq to Sql database application, with a table set up with a datetime field (allow Null). I am able to submit 'Nothing' into the datetime field after setting my .dbml table | field | property to AutoGenerated = True. Why this is I don't know, but it works. Now that I can submit an empty datetime field to the database, I am having trouble loading it into an object with a property set as datetime.
Example: of property in object
Private _deliveryDate As DateTime = Nothing
Public Property DeliveryDate() As DateTime [code]...
Example: setting value when instanciating the obect
dim test as new dateObject(Nothing, ...) ' where (Nothing) represents the datetime field retrieved from the database set to null.When I try the above line I get "Nullable object must have a value."
How do I allow nullable string to my declaration?
I get this error "Type 'String' must be a value type or a type argument constrained to 'Structure' in order to be used with 'Nullable' or nullable modifier '?'." [:(]
Function Index(ByVal product As Product, ByVal category_1 As Nullable(Of String), ByVal category_2 As
Nullable(Of String)) As ActionResult
...
End Function
This is actually a situation where LINQ as follow:
Code:
Dim query = From loadedfile In dtloadedfile.AsEnumerable() _
Join householdPanels In dtHouseholdPanels.AsEnumerable() _
On CType(loadedfile("Household_number"), Integer) Equals _
[code]...
when i get to col.DataType = t.PropertyType, i hit an error where it says Nullable datatype is not allowed. I know the t.propertytype returns nullable as datatype, however, this nullable type do have a normal datatype declared too. ie Of System.Nullable(Of Integer) from the LINQ query. But how do i get that information?
ps: this function is taken somewhere from the web, so you might recognise it.
I remember being told that you can add some syntax to the end of a statement that will do something if the field is null. Pretty vague, but I cant seem to find anything about it via google.
I definitely isnt how to set a field to be nullable. I know that.
Here is an example of what I want.
int? field1 = 0;
field1 = int.parse(string2); (where string2 is a passed value, that could be null)
I thought there was something you could put at ?? if it is a null, such as:
field1 = int.parse(string2) ??;
Or do I have to check every if every string2 is null before making that statement.
Can anyone reliably get the EDS to save a nullable column to the databse as a "null" when bound to any of the controls such as "FormView"?I have tried using several different UpdateParameters (Session, ControlParamater, Parameter, etc). I have tried setting "ConvertEmptyStringToNull" to true and leaving the property off entirely. Nothing works. On my "Inserts" it works fine.(I have made sure the column is set to nullable = true in the Entity Designer.....)
View 7 RepliesI want to convert the following SQL line to LINQ :
[Code]....
How to bind nullable bool to checkbox in MVC 2. I try with this code in view:
<%: Html.CheckBoxFor(model => model.Communication.Before)%>
But show me compilation error.
I'm posting Json data to an action that has a model class as a parameter using the
JsonValueProviderFactory. Everything works except for any nullable properties in the model, such as double? and bool? - they always materialize as null, even if a value is posted.
I'm not sure if this issue is specific to the JsonValueProviderFactory, or MVC in general.
I have 2 objects, that can exist seperately - lets say man and woman, neither needs to know about the other. But once they get get "married" it can only be married to each other. In other words, I'm trying to create 2 tables, 1 table has a FK to the other, that is NULLABLE. When i try to set the relationship to 1-to-1 via the dmbl, it wont let me - which makes sense. Ultimate i want to
1) create a women (no knowledge of a man)
[Code]....
Is this even possible? If i do a one-to-many - how can i make it act this way? At the business layer? create a partial class and override stuff?
1) create a women (no knowledge of a man)
My designer.cs file of all the SQL tables is generated by LINQ-TO-SQL. The class and attribute in question is like this.
[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Transfers")]
public
partial
class
Transfer :INotifyPropertyChanging,[code]...
I need to assign a null to the attribute so that the value 0 does not get save to the database.
The C# code below:
int? i;
i = (true ? null : 0);
gives me the error:
Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'int' Shouldn't this be valid?
I've got a route that I want to be able to pass nullable values to. I was using MVC 1 but updated my solution to MVC 2 to take advantage of UrlParameter.Optional.
My route look like:
[Code]....
Which works fine if I go to http://localhost:1234/Search.aspx/l-1/t-1/p-1/s-1 but when I go tohttp://localhost:1234/Search.aspx/l-/t-/p-1/s- or any combination with missing parameters I keep getting 404's.
Also on a related note since I've upgraded to MVC 2 I can no longer use RedirectToRoute for the above route I get the following error: No route in the route table matches the supplied values. Whereas in MVC 1 it would redirect to it without any problems.
I don't know how to bind nullable boolean field to RadioButton in ASP.net.
Following code works well for non-nullable field
<asp:RadioButton ID="rbStatus" runat="server" Text="Accepted" Checked='<%# Bind("Status") %>' />
how I can bind nullable boolean field to RadioButton?
I have (or so I think!) a simple problem.
I will greatly simplify my model to speed this along.
I have a model class lets call it item:
public class Item
{
[Required(ErrorMessage="Must indicate if product is to be tracked by serial number.")]
public bool TrackedBySerial { get; set; }
}
I have an "Add" view where I create a DropDownList like so:
<%= Html.DropDownListFor(model=>model.TrackedBySerial, new SelectList(new List<object> {null,true,false},null),"Select One") %>
<%= Html.ValidationMessageFor(model => model.TrackedBySerial) %>
My problem is that unless I create my boolean value in the model to be a nullable type, I can't force the blank default value.
If I use the Html.DropDownList() instead of DropDownListFor() , is there any way for me to use ModelState.IsValid -- or do I need to mix my own custom validation in my controller as well?
Update: So I got the functionality I was looking for, its just a bit more verbose than I'd have liked. Is there a better way to do this?
Controller:
[HttpPost]
public ActionResult Add(InventoryItem newItem)
{
try
{
//get the selected form value
string formVal = Request.Form["TrackBySerial"];
//convert to true, false, or null
bool? selectedValue = TryParseNullable.TryParseNullableBool(formVal);
//if there is no value, add an error
if (!selectedValue.HasValue).....
view:
<div class="editor-field">
<%=Html.DropDownList("TrackBySerial","- Select One- ") %>
<%=Html.ValidationMessage("TrackBySerial") %>
<%= Html.ValidationMessageFor(model => model.TrackedBySerial) %>
</div>
I can create a custom control with a default value:
private bool exclue = false;
public bool Exclude { get { return exclue; } set { exclue = value; } }
I can Create the same thing with a nullable property:
private EntityStatuses? status = EntityStatuses.Active;
public EntityStatuses? Status { get { return status; } set { status = value; } }
But how can i then set the property to null in markup when using the custom control?
<MyControls:Control ID="Con" runat="server" Status="?" >
I have a question regarding routing and an issue that I am currently having in my application. I have an action, providers/List/, which accepts two parameters, a zipCode and a page value for paging results. I have defined this route as follows in my global.asax, /providers/{zipCode}/{page}
I have created another action in this controller, Dashboard, which does not expect any parameters, so I am assuming that the route would ultimately be /providers/dashboard, if I am not mistaken. What is happening is that for some reason I am getting a routing error regarding zipCode not being a non-nullable type. It makes me think that the first action's route is what is getting hit instead of going to the dashboard action. I am sure that it has something to do with the route entry that I have made in my global.asax file.
I have a textbox that I use to gather a date. I would like to have the database store a null if this field is left blank by the user when submitting. I am using the following on my aspx page:
<div class="col-md-3">
<strong>Date Submitted to TDI</strong><br />
<asp:TextBox ID="sub_tdi_dt" runat="server" Enabled="true"></asp:TextBox>
<asp:ImageButton ID="sub_tdi_dt_cal_popup" Enabled="false" ImageUrl="Images/calendar.png" ImageAlign="Bottom" runat="server" />
<ajaxToolkit:CalendarExtender runat="server" BehaviorID="sub_tdi_dt_CalendarExtender" PopupButtonID="sub_tdi_dt_cal_popup" TargetControlID="sub_tdi_dt" ID="sub_tdi_dt_CalendarExtender"></ajaxToolkit:CalendarExtender> </div>
I have tried using the following in Page_Load, but it doesn't work - I still get '1/1/1900':
DateTime? sub_tdi_dt = null;
I have a master document which is composed of other document types (some are required and some are not). While the master document's status is "Draft" I need to ignore all not nullable constraints (because the writer may decide to work on one of the children
documents that is not required and save as draft).
The closest solution I found for this problem is check constraints but I have not yet to see an example of this in check contraint and I'm not even sure if this is possible. Has anyone implemented a similar solution with check constraints (or any other methods)?
I have the following function signuture:
public JsonResult PopulateGrid(int page, Guid? accountId, Guid? systemUserId, Guid? branchId, DateTime? fromDate, DateTime? toDate, HomeVisitType? homeVisitType)
Every single parameter is bound just fine except toDate which turns out to be always null. When inspecting the Request.QueryString["toDate"] it retrives the right value which is 30/09/2010. It seems that DateTime expects another format when binding.
What is the right format?