I'm looking at server controls for the first time, and I've a question about this code:
[Bindable(true)]
[Category("Appearance")]
[DefaultValue("")]
[Localizable(true)]
public string Text
{
get
{
String s = (String)ViewState["Text"];
return ((s == null) ? "[" + this.ID + "]" : s);
}
set
{
ViewState["Text"] = value;
}
}
I do not understand why this control returns the [id] or the text that is set. I do not see how this makes any sense. Is this just for demonstration or is there a reason for returning the id?
Thanks
It looks like an example that will show the controls ID if the controls .Text property has not been set.
This is a bit of a "debug" procedure to show that the control is actually rendering even though it hasn't got any data set in it's Text property.
Makes no sense to me. If I'm asking for text, then I expect if there is no text to get either an empty string or null.
If there's nothing been set for the Text property, in ViewState with other words, then this.ID gets returned.
There's not really a meaning for it but it'll show some text in the Property pane of Visual Studio and on the designer.
Related
I have encountered a problem and I didn't manage to find any soultions yet. Let me simplify things a bit.
I have 2 forms, the first contains an ASP ListBox with multi select mode enabled. I submit the form and in the other form I use just for testing purposes this snippet of code:
protected void Page_Load(object sender, EventArgs e)
{
foreach (string formKey in Request.Form.AllKeys)
{
if (formKey != null)
{
if (formKey.Equals("ctl00$MainContent$ListBox1"))
Label1.Text = Request.Form[formKey];
}
}
}
The problems is that the values that come from the listbox (the values that i selected in the previous form) are separated by "," for ex. "test1,test2,test3". How can i change this separator to "$" for example? I need to change it because the actual values may contain "," and i don't manualy feed them to the listbox.
I can't use any other mode of transfering this values between the form because the entire application uses this model. The values that i get are then sent to a workflow where there will be manipulated and in the workflow i need to know where each listbox item starts and ends so it must be an unique separator.
Any help is apreciated! Thank you very much
Thank you MatteKarla but unfortunately this does not solve my problem. Yes, this is a good way of transfering the values from one form to another.
However i must use the method I described above with Request form keys because the listbox is one of many others "parameters" that are generated at runtime and have their values sent to a workflow method that takes this values. And i can't afford to change that in my application.
My problem is that coma (",") separator is used by default with a multiselect listbox.
I thought that there maybe is a method to change that separator from coma to another char because the coma can also be included in the value itself and this will create confusion.
As i said if i select three values test1, test2 and test3, the result with my method will be a string looking like "test1,test2,test3". However a "test1$test2$test3" would be much better.
But I'm affraid that changing this default separator is not possbile. I must think at a method to overcome this problem like replacing before feeding the listbox all the intended coma from the values with some other char not to create confusion. But this is not a great way of doing it.
On your first page/form (First.aspx.cs) create a public property with the listbox:
public ListBox PostedListBox { get { return ListBox1; } }
Set the postback-url for the button to Second.aspx
Second page in the aspx-file after the #Page-directive add:
<%# PreviousPageType VirtualPath="~/First.aspx" %>
Then in Form_Load on Second.aspx.cs you can extract the values:
if (PreviousPage != null)
{
ListBox postedListbox = PreviousPage.PostedListBox;
foreach (var index in postedListbox.GetSelectedIndices())
{
var itemText = postedListbox.Items[index].Text;
}
}
Or you could just try to locate the control by using:
if (PreviousPage != null)
{
var control = PreviousPage.FindControl("ListBox1") as ListBox;
}
Third Edit:
You could use GetValues:
Request.Form.GetValues("ctl00$MainContent$ListBox1");
returns a string array containing each of the selected items.
I am creating a custom server control with a property that accepts a String as input. What is the correct way to handle whitespace/tabs & newlines? For example,
<prefix:MyControl runat="server"
Property="This is a long text string which is manually
wrapped in the VS text editor on multiple
lines."
>
</prefix:MyControl>
This returns something similar to
"This is a long text string which is
manually\r\n
wrapped in the VS text
editor on multiple\r\n
lines."
Is there a special attribute I can apply to the propery to help with this? I have checked Metadata Attributes for Custom Server Controls Or do I need to manually strip the linebreaks and extra spacing?
Discovered a Regular Expression solution which finds multiple whitespace characters preceded by a line break and replaces matches with a single space.
private string property;
[Bindable(true)]
public string Property {
get { return property; }
set {
property = Regex.Replace(value, #"(\n|\r|\r\n)\s+", " ");
}
}
I have a string str = "txtName.Text" (txtName is name of textbox control)
How to display value of textbox without is value of string str (use C#)
Let me a solution.
Thanks a lot !
Probably the easiest thing to do would be to extract the control id like this:
String controlId = str.Substring(0, str.IndexOf('.'));
Then use the Page.FindControl method to find the control and cast that as an ITextControl so that you can get the Text property value:
ITextControl textControl
= this.FindControl(controlId) as ITextControl;
if (textControl != null)
{
// you found a control that has a Text property
}
I assume that the question is: How to get value of textbox control given its ID as a string.
Use FindControl method.
Example:
TextBox myTextBox = FindControl("txtName") as TextBox;
if (myTextBox != null)
{
Response.Write("Value of the text box is: " + myTextBox.Text);
}
else
{
Response.Write("Control not found");
}
If by "value" you mean "numeric value", then you can't - text boxes contain strings only. What you can do is get the string like you did, and parse that string into a number.
You can use int.Parse() or double.Parse() (depending on the type), or TryParse() for a safer implementation.
I want to bind a List to a GridView on a web page, but override the way the property names display via annotation. I thought System.ComponentModel would work, but this doesn't seem to work. Is this only meant for Windows Forms?:
using System.ComponentModel;
namespace MyWebApp
{
public class MyCustomClass
{
[DisplayName("My Column")]
public string MyFirstProperty
{
get { return "value"; }
}
public MyCustomClass() {}
}
Then on the page:
protected void Page_Load(object sender, EventArgs e)
{
IList<MyCustomClass> myCustomClasses = new List<MyCustomClass>
{
new MyCustomClass(),
new MyCustomClass()
};
TestGrid.DataSource = myCustomClasses;
TestGrid.DataBind();
}
This renders with "MyFirstProperty" as the column header rather than "My Column." Isn't this supposed to work?
When using .net 4 or later you can use gridview1.enabledynamicdata(typeof(mytype)). I haven't looked at all the types you can use there but I know the [displayname("somename")] works well but the [browsable(false)] doesn't omit the column from the grid. It looks like a knit one slip one from MS. at least you can easily rename column names and to omit a column I just declare a variable instead of using a property. It has the same effect...
Just by the way, using the designer to create columns is the easy way out but to just show a different column name takes way to much time especially with classes with many fields.
What SirDemon said...
The answer appears to be no, you can't. At least not out of the box.
The System.Web.UI.WebControls.GridView uses reflected property's name:
protected virtual AutoGeneratedField CreateAutoGeneratedColumn(AutoGeneratedFieldProperties fieldProperties)
{
AutoGeneratedField field = new AutoGeneratedField(fieldProperties.DataField);
string name = fieldProperties.Name; //the name comes from a PropertyDescriptor
((IStateManager) field).TrackViewState();
field.HeaderText = name; //<- here's reflected property name
field.SortExpression = name;
field.ReadOnly = fieldProperties.IsReadOnly;
field.DataType = fieldProperties.Type;
return field;
}
While System.Windows.Forms.DataGridView uses DisplayName if available:
public DataGridViewColumn[] GetCollectionOfBoundDataGridViewColumns()
{
...
ArrayList list = new ArrayList();
//props is a collection of PropertyDescriptors
for (int i = 0; i < this.props.Count; i++)
{
if (...)
{
DataGridViewColumn dataGridViewColumnFromType = GetDataGridViewColumnFromType(this.props[i].PropertyType);
...
dataGridViewColumnFromType.Name = this.props[i].Name;
dataGridViewColumnFromType.HeaderText = !string.IsNullOrEmpty(this.props[i].DisplayName) ? this.props[i].DisplayName : this.props[i].Name;
}
}
DataGridViewColumn[] array = new DataGridViewColumn[list.Count];
list.CopyTo(array);
return array;
}
Unfortunately, while you can override the CreateAutoGeneratedColumn, neither the missing DisplayName nor underlying property descriptor gets passed, and you can't override CreateAutoGeneratedColumns (although you could CreateColumns).
This means you'd have to iterate over reflected properties yourself and in some other place.
If all you care about is the header text in GridView, just use the HeaderText property of each field you bind. If you're autogenerating the columns, you just set the HeaderText after you've bound the GridView.
If you want a GridView that takes into account some attribute you placed on the properties of your bound class, I believe you'll need to create your own GridView.
I may be wrong, but I've not seen any ASP.NET Grid from control vendors (at least Telerik , Janus Systems and Infragistics) do that. If you do it, maybe sell the idea to them.
Are you using .net4, what you need to do is to set enabledynamicdata on the grid view to true.
You can do it now on asp.net mvc2. It works just like that
Ive no problems using Javascript to read the rows of a telerik radgrid component im using however I can seem to find anyway to access the row data server side when a postback occurs. Ive spent ages looking for solution but no luck.
Any pointers would be greatly appreciated.
Tony
You might want to look at the DataKeyValues property of the OwnerTableView object, which will let you access a collection of values that represent the fields in a given row. I use it during the EditCommand event handler, since a user of my site is directed to an edit page if they click on the link to edit a row in the grid, and I need to pass along certain info about the given row in the query string.
If this turns out to be what you need, you'll also need to define which fields should be made available through this property. To do that, look at the MasterTableView.DataKeyNames property in the property sheet for the grid. You basically specify a comma-delimited list of field names.
The server-side is the easy part:
GridItemCollection gridRows = TestGrid.Items;
foreach (GridDataItem data in gridRows)
{
ItemClass obj = (ItemClass)data.DataItem;
}
It's the client side part that I don't know! :[
private Int32 GetID()
{
foreach (Telerik.Web.UI.GridDataItem dataItem in radGrid.MasterTableView.Items)
{
if (dataItem.Selected == true)
{
Int32 ID = (Int32)dataItem.GetDataKeyValue("ID");
return ID;
}
}
throw new ArgumentNullException("Id Not found");
}
This is the one that works for me and uses the RadGrid.SelectedItems collection.
protected void LinkButton1_Click(object sender, EventArgs e)
{
List<Guid> OrderIdList = new List<Guid>();
foreach (GridDataItem OrderItem in this.RadGrid1.SelectedItems)
{
OrderIdList.Add(new Guid(OrderItem.GetDataKeyValue("OrderId").ToString()));
}
}
If you correctly created your controls in markup or page init for dynamic controls, then the RadGrid will properly restore state.
You can access the initial values that were loaded from the data source like this example below, provided you told the table view in question to keep the columns around in the data keys.
protected T GetInitialGridData<T>(GridDataItem item, string uniqueColumnName) {
item.ThrowIfNull("item");
uniqueColumnName.ThrowIfNullOrEmpty("uniqueColumnName");
return (T)item.OwnerTableView.DataKeyValues(gridItem.ItemIndex)(columnName);
}
If you are using a dynamic custom template column, and need to get to any values that may now be in their states, you can use:
protected string GetCustomTextBoxValue(GridDataItem item, string controlID) {
item.ThrowIfNull("item");
controlID.ThrowIfNullOrTrimmedEmpty("controlID");
return ((TextBox)item.FindControl(controlID)).Text;
}
private Int32 GetID()
{
foreach (Telerik.Web.UI.GridDataItem dataItem in radGrid.MasterTableView.Items)
{
if (dataItem.Selected == true)
{
// Int32 ID = (Int32)dataItem.GetDataKeyValue("ID");
Int32 ID =Convert.ToInt32(dataItem.GetDataKeyValue("ID"));
return ID;
}
}
}
//this will work