I have a form where I have lots of textboxes and all of them are required to be filled out. In C# how do I actually if check there are group of fields having a null or whitespace?
I am familiar with string.isNullOrWhiteSpace(string here) but I don't want to do multiple if statements of that, it would result in a bad code.
I am trying to avoid something like this
if(string.isNullOrWhiteSpace(string here)
|| string.isNullOrWhiteSpace(string here)
|| string.isNullOrWhiteSpace(string here))
{
// do something
}
Are there fix for this type of bad code?
You can query the controls collection of the form (or relevant container) and filter for textboxes and further query to see if any are empty (none should really have null values). Example:
var emptyTextboxes = from tb in this.Controls.OfType<TextBox>()
where string.IsNullOrEmpty(tb.Text)
select tb;
if (emptyTextboxes.Any())
{
// one or more textboxes are empty
}
You can do effectively the same thing using the fluent syntax.
bool isIncomplete = this.Controls.OfType<TextBox>().Any(tb => string.IsNullOrEmpty(tb.Text));
if (isIncomplete)
{
// do your work
}
For this code, you should be working with at least Visual Studio 2008 / C# 3 / .NET 3.5. Your project needs to have a reference to System.Core.dll (should have one by default) and you need a using System.Linq; directive in the class file.
Based upon your comments, consider another method if you are having trouble understanding or working with the linq version. You can certainly do this in an explicit loop (the Linq code will ultimately be a loop as well). Consider
bool isIncomplete = false;
foreach (Control control in this.Controls)
{
if (control is TextBox)
{
TextBox tb = control as TextBox;
if (string.IsNullOrEmpty(tb.Text))
{
isIncomplete = true;
break;
}
}
}
if (isIncomplete)
{
}
Finally, this code is written as if all of the textboxes are in a single container. That container might be the form, a panel, etc. You will need to point to the appropriate container (eg., instead of this (the form) it might be this.SomePanel). If you are working with controls that are in multiple and perhaps nested containers, you will need to do more work to find them programmatically (recursive searching, explicit concatenation, etc.) or you might just preload the references into an array or other collection. For example
var textboxes = new [] { textbox1, textbox2, textbox3, /* etc */ };
// write query against textboxes instead of this.Controls
You said you have multiple GroupBox controls. If each GroupBox is loaded onto the form and not nested in another control, this may get you started.
var emptyTextboxes = from groupBox in this.Controls.OfType<GroupBox>()
from tb in groupBox.Controls.OfType<TextBox>()
where string.IsNullOrEmpty(tb.Text)
select tb;
That depends on what you consider "bad code." Depending on your requirements what text boxes are required to be filled out can vary. Further, even if all of the fields are required all of the time you still want to give friendly error messages letting people know which field they didn't fill out. There a variety of approaches to solving this issue depending on how you are rendering your form. Since you haven't specified any here's a very direct method for doing so.
var incompleteTextBoxes = this.Controls.OfType<TextBox>()
.Where(tb => string.IsNullOrWhiteSpace(tb.Text));
foreach (var textBox in inCompleteTextBoxes)
{
// give user feedback about which text boxes they have yet to fill out
}
Yet another solution.
This will recursively travel the whole control Tree , and Check for null or empty text in all of the textboxes.
caveat -
If you have some fancy controls not inheriting from the standard Winforms textbox - check will not be performed
bool check(Control root,List<Control> nonFilled)
{
bool result =true;
if (root is TextBox && string.isNullOrEmpty(((TextBox)root).Text) )
{
nonFilled.Add(root);
return false;
}
foreach(Control c in root.Controls)
{
result|=check(c,nonFilled)
}
return result;
}
Usage :
List<Control> emptytextboxes=new List<Control>()
bool isOK=check(form, emptytextboxes);
Related
The calculator I have made is a combination of textboxes and radiobuttons and when 'calculate' is clicked, I would like a message box to check the whole program and then (if necessary) display a message box saying something like 'the following areas still need completing' and then list those areas.
I know how to code a basic if lI have made is a co't know how to get it to check multiple textboxes and radiobuttons in one go.
The current code for the button is:
private void button4_Click(object sender, EventArgs e)
{
DrawForce = (Area2 * (StrengthCoeff / (WorkHardExp + 1)) * (Math.Pow(Math.Log(Area1 / Area2), WorkHardExp + 1)));
DrawForce = Math.Round(DrawForce, 2);
textBox7.Text = DrawForce.ToString() + " N";
}
I don't wish to copy the enter code onto here so I hope that will suffice
Thanks
If I understand you correctly, you're looking for a way to check many controls on the form in a loop. There are a couple of ways to do this.
One way would be to create a class-level collection on the form which holds references to the controls. For example, something like this:
private IEnumerable<TextBox> textBoxes = new List<TextBox>
{
TextBox1,
TextBox2,
TextBox3
};
Then you can examine it in a loop:
var errors = new List<string>();
foreach (var textBox in textBoxes)
if (string.IsNullOrWhitespace(textBox.Text))
errors.Add(string.Format("{0} is empty.", textBox.Name));
// errors now contains the list of validation messages
The downside to this is that you'd need to manually keep the collection updated if you change the form. If there aren't going to be many changes, that shouldn't be a problem.
Another option could be to loop through the Controls collection of the form. Something like this:
var errors = new List<string>();
foreach (var control in Controls)
if (control is TextBox)
if (string.IsNullOrWhitespace((control as TextBox).Text))
errors.Add(string.Format("{0} is empty.", (control as TextBox).Name));
// errors now contains the list of validation messages
This is more dynamic, but a little more brittle as well. If there are any text boxes nested in other controls then this won't find those, you'd need to make this more recursive to loop through control.Controls as well. That could get a little ugly, and might not be worth it if the form isn't likely to change. But either way, it might look something like this:
private IList<string> GetErrorsForControls(ControlCollection controls)
{
var errors = new List<string>();
foreach (var control in controls)
{
if (control is TextBox)
if (string.IsNullOrWhitespace((control as TextBox).Text))
errors.Add(string.Format("{0} is empty.", (control as TextBox).Name));
errors = errors.Concat(GetErrorsForControls(control.Controls));
}
return errors;
}
Then in your code you'd just invoke that method:
var errors = GetErrorsForControls(Controls);
To add validation for other types of controls besides text boxes, simply add other class-level collections or add other type checks in the loops.
I'm good with Loading the control, using the LoadControl("~/vitrualPath"), so I have:
UserControl ctrl = (UserControl)LoadControl("~/controls/someControl.ascx");
this.Controls.Add(ctrl);
//plcCtrl.Controls.Add(ctrl);
The trouble is that I wish to then loop through all the controls in the usercontrol:
foreach (Label c in this.Controls.OfType<Label>())
{
// It's a label for an input
if (c.ID.Substring(0, 8) == "lblInput")
{
// Do some stuff with the control here
}
}
However, the added controls aren't part of this, but part of ctrl
Is there a way I can add the contents of the loaded control to this or a way to loop through both this and ctrl in one hit?
If you simply want to loop through both top-level labels and labels in ctrl, try this.Controls.Concat(ctrl.Controls).OfType<Label>() in your foreach loop.
You can also move your if into a LINQ Where call:
.Where(l => l.ID.Substring(0, 8) == "lblInput")
By using a recursive function you don't need to worry about controls within sub levels/ containers. Something like this should be OK (all you need to do is to pass the top level control along with the id substring that you are interested in). So if the conditions are met it will do whatever you have intended to do with the control and at any sub level.
public void ProcessControl(Control control, string ctrlName)
{
foreach (Label c in control.Controls.OfType<Label>())
{
// It's a label for an input
if (c.ID.Substring(0, 8) == ctrlName)
{
// Do some stuff with the control here
}
}
foreach (Control ctrl in control.Controls)
{
ProcessControl(ctrl, ctrlName);
}
}
You should write a recursive method that starts looping the controls in this.Controls and goes down the tree of controls. It will then also go in your user control and find your labels.
I don't think there is a way to loop through both like you want.
You can easily create a method that receives a Control as parameter and iterate though its controls. Something like this:
void Function(Control control)
{
foreach (Label c in control.Controls.OfType<Label>())
{
// It's a label for an input
if (c.ID.Substring(0, 8) == "lblInput")
{
// Do some stuff with the control here
}
}
}
You should be able to access the controls inside the user control by accessing the this.Controls[index].Controls I think, however it kind of depends what you are trying to achieve? Their might be a cleaner way of doing what you are trying to do?
I've written a web user control which I want to be able to drop into the markup for either aspx pages or other web user controls.
I need my user control to be able to easily and efficiently work out if its inside another user control or an aspx page. My initial idea is to do it recursively with checks on the Parent property - continue looking up the nesting hierarchy until I find either a web form or a user control - but I'm not sure this the best way of going about this.
Can you suggest an easier way? Thanks.
Recursively check the type of your Parent until Parent.GetType() is either typeof(UserControl) or type(Page)
private bool IsAncestorTypeOf(Control c, params Type[] typesToCheck)
{
var parent = c.Parent;
if (parent == null) return false;
if (typesToCheck.Contains(parent.GetType())) return true;
return IsAncestorTypeOf(parent, typesToCheck);
}
Or the same without recursion
private bool IsAncestorTypeOf(Control c, params Type[] typesToCheck)
{
var parent = c.Parent;
while (true)
{
if (parent == null) return false;
if (typesToCheck.Contains(parent.GetType())) return true;
parent = parent.Parent;
}
}
Call it like
var isAncestorPageOrUserControl = IsAncestorTypeOf(this, typeof(Page), typeof(UserControl));
or
var isAncestorPage = IsAncestorTypeOf(this, typeof(Page));
var isAncestorUserControl = IsAncestorTypeOf(this, typeof(UserControl));
Generally, components should be unaware of their arbitrary containers, although the containers must know their components (unless it's a strong dependency situation like list items are always in a list type and you can make a strong two way relationship). However it sounds like you are reaching out into the general surroundings. You might find many cases to code for doing this and accidentally miss others.
By making the user control aware of its surroundings and the larger world you may be introducing dependencies that make your control less reusable and harder to maintain.
If something the control needs is outside of itself, you might move toward composition by forcing the developer to provide a reference to the needed thing on a property of your user control. This is the way, for example, that validation controls in ASP.NET do it, to reference an external control to validate by id.
Of course what I specified is practical only some of the time. Is there a specific reason or edge case why you need to make your user control look around itself, or can you get away with providing instructions to the developer about where the control should be used?
This should work:
C#
bool inPage = (this.NamingContainer == this.Page);
VB.NET
Dim inPage as Boolean = Me.NamingContainer is Me.Page
Edit: it seems to be not as simple as i hoped. If the usercontrol resists in a control like a GridViewRow, the NamingControl of it would be the Row and not the Page.
This takes it into account:
C#
public static bool isControlInPageOruserControl(Control uc)
{
bool inPage = uc.NamingContainer is Page;
if (inPage) {
return true;
} else if (uc.NamingContainer is UserControl) {
return false;
} else {
return isControlInPageOruserControl(uc.NamingContainer);
}
}
VB.NET:
Public Shared Function isControlInPageOruserControl(ByVal uc As Control) As Boolean
Dim inPage As Boolean = TypeOf uc.NamingContainer Is Page
If inPage Then
Return True
ElseIf TypeOf uc.NamingContainer Is UserControl Then
Return False
Else
Return isControlInPageOruserControl(uc.NamingContainer)
End If
End Function
Example code:
var div = new HtmlGenericControl("div");
div.Controls.Add(new Literal() { ID = "litSomeLit" });
var lit = (Literal)div.FindControl("litSomeLit");
Assert.IsNotNull(lit);
This code fails the assert, because lit is null. Debugging shows that div.Controls definitely contains a literal with ID of "litSomeLit." My questions are "Why?" and "Is there any way to get a control of a specific ID without doing a recursive search of div.Controls[] by hand one element at a time?"
The reason I'm doing things this way is that my actual application is not so straightforward- a method I'm writing is given a complex control with several subcontrols in a number of possible configurations. I need to access a specific control several layers down (eg, the control with ID "txtSpecificControl" might be at StartingControl.Controls[0].Controls[2].Controls[1].Controls[3]). Normally I could just do FindControl("txtSpecificControl"), but that does not seem to work when the controls were just dynamically created (as in the above example code).
Near as I can tell, there is no way to do what I'm trying to accomplish without adding the control to the page. If I had to guess, I'd say that FindControl uses the UniqueID property of the control, which generally contains the IDs of all the controls above the current one (eg OuterControlID$LowerControlId$TargetControlID). That would only get generated when the control actually gets added to the page.
Anyway, here's an implementation of recursive depth-first-search FindControl that'll work when the control is not attached to the page yet:
public static Control FindControl(Control parent, string id)
{
foreach (Control control in parent.Controls)
{
if (control.ID == id)
{
return control;
}
var childResult = FindControl(control, id);
if (childResult != null)
{
return childResult;
}
}
return null;
}
Change your code to
var div = new HtmlGenericControl("div");
Page.Controls.Add(div);
div.Controls.Add(new Literal() { ID = "litSomeLit" });
var lit = (Literal)div.FindControl("litSomeLit");
As far as i know FindControl only works when the control is in the visual tree of the page.
When you confirmed that the control was in the Controls collection, did you do that by inspecting the collection directly? FindControl() may not work in this context.
When you debug the test, is the var lit null? If so, you may have to access the member by item index instead of using the FindControl() method.
I am looking for a way to loop through controls on a particular tab of a tabcontrol. For example, I have a tabcontrol with the following tabs:
Cars,
Pets,
Admin
On each of these tabs are several controls to display/edit/save data, etc. On the "Save" button, I would like to loop through the controls for that particular tab to check whether all required fields have been filled in.
So, if I am on the Cars tab and click "Save," I want to loop ONLY through the controls on the Cars tab and NOT the Pets or Admin tabs.
How can achieve this result?
As for looping through a TabControl's controls, you need to use the Controls property.
Here's an MSDN article on the TabControl.
Example:
TabPage page = aTabControl.SelectedTab;
var controls = page.Controls;
foreach (var control in controls)
{
//do stuff
}
I feel it's important to note that, in general, you should take a more structured approach to your application. E.g., instead of having all the controls on three tab pages, include exactly one UserControl on each tabpage. A CarUserControl, PetUserControl, and AdminUserControl e.g. Then each user control knows how to create the proper respective data structure so you don't have to manually munge it all together at the same level of abstraction using inter-tab loops and whatnot.
Such a separation of concerns will make it much easier to reason about your program and is good practice for writing maintainable code for your future career.
Example where I wanted to get the DataGridView in a particular tab for an application I wrote.
TabPage pg = tabControl1.SelectedTab;
// Get all the controls here
Control.ControlCollection col = pg.Controls;
// should have only one dgv
foreach (Control myControl in col)
{
if (myControl.ToString() == "System.Windows.Forms.DataGridView")
{
DataGridView tempdgv = (DataGridView)myControl;
tempdgv.SelectAll();
}
}
The Controls property is the way to go...
foreach(Control c in currentTab.Controls)
{
if(c is TextBox)
// check for text change
if(c is CheckBox)
//check for check change
etc...
}
TabControl has a SelectedTab property, so you'd do something like this:
foreach(Control c in tabControl.SelectedTab.Controls)
{
//do checks
}
foreach (Control c in this.tabControl1.SelectedTab.Controls)
{
// Do something
}
I had the need to disable or enable controls of a tab as well. I had to go a bit more generic though. Hope it helps people and I didn't make a mistake
private void toggleControls(Control control, bool state)
{
foreach (Control c in control.Controls)
{
c.Enabled = state;
if (c is Control)
{
toggleControls(c, state);
}
}
}