I am creating a web control in vb.net that contains a list box. I know that I am able to choose a selection mode of Single or Multiple, but I am interested in limiting a Multiple selection to a predetermined size. For example preventing a user from selecting more than 3 items.
I have tried adding a Validator to the list box, which might be a way forward, but was wondering if there was a way of changing the selection mode to something a bit different than just the two specified ones.
Any ideas or suggestions would be greatly appreciated
Edit: Unfortunately due to project limitations I am unable to use Javascript on this problem. very annoying I know!
You could try handling one of the SelectedIndexChange events. With multiple selection, each time this event fires you can check how many items have already been selected. If it is more than you want, have the handler deselect the one that was just selected. You could also put up a little red label under the listbox saying "Sorry, no more than [n] selections allowed."
EDIT:
Just noticed you said WEB. Same theory applies, but it would have to be done using Javascript.
On the SelectedIndexChanged event, write a short piece of code that will check the number of selected items and if it is greater than your desired amount, unselect the new selection (or unselect the oldest one, or however you wish this to operate).
Related
I have a database where I don't want some fields showing depending on data in other fields. I'm still new to VBA, having learnt how to do things I need via the internet (there's not much call for it in my job so like to try it out on side projects) for the things I need and have managed to create some code that hides certain fields that aren't needed, depending on what's been entered in another field and that works okay, if not perfectly (I'd like it to only work on the current record and not all of them at once but will worry about that later). My problem is, if I'm entering information onto a record and any of those fields become invisible exactly as I would want them to, then if I have more records to complete and load a new record, those hidden fields are also hidden on the blank record before any data has been entered and I want each new record to show all fields from the outset.
Another thing I've noticed is that if I close the database, next time I go into it the hidden fields have unhidden themselves again so I know I'm missing something important.
Here's a screenshot of a bit of the code where I want 2 other fields (What_reason and Date_sent_to_new_owning_School) to be visible depending on whether the answer in the current field after update is "Standard" or "Non-standard":
I'm sorry if this is really entry-level stuff but I AM entry level and trying to learn. This bit does work, albeit not perfectly as I'd like it to only work on the record I'm in at the time, and not go through and hide that field in all the other records at once (which it's doing).
I've searched everywhere but can't find the answer and although I've tried, I'm nowhere near good enough at VBA to try and use common sense to work it out. Is this something that can be done? I'm okay with computers generally and with Access too but I'm aware there's an awful lot I don't know and this is why I'm trying to do new things and learn stuff that I've not used before. I have tried all day to get this to work but am admitting defeat and am hoping somebody here will be able to help me. I'll probably need 'idiot level' advice if that's possible, I know my limitations. :)
Do you know how to use the Event tab in the Property Sheet? You can set all of your fields to [field].Visible = True on either: On Current, On Load, or On Open
Screenshot of the Property Sheet and for the field that determines the visibility of all of the other fields; you can use the Event: After Update so that way when you click/tab away from that field, it'll make those changes for you!
Property setting affects ALL instances of control. Control will be visible/not visible for all records depending on conditions of current record. Therefore, dynamically hiding controls on form set in Continuous or Datasheet will NOT give the desired result of
only work on the current record and not all of them at once
Db is not going to 'remember' dynamic setting - code needs to be executed when form opens and/or navigating records - so it is needed in OnCurrent event as well as control's AfterUpdate.
Conditional Formatting can dynamically enable/disable textbox/combobox by record although control is still visible.
My scenario: I have a datagridview and it contains some data. User can select a row, or multiple rows in that datagridview, and they need to know a summary about those rows they selected.
Handling multiple rows in datagridview is easy enough, and I have no problem getting what the user need: Two numbers indicate how many item is selected, and their total weight in those rows. I passed that data to a small summary form to display, and I put the code to show that form under dgv.SelectionChange().
But then disaster follow: each time user select a row, that form will appear. Which is, if user select 20 rows, they will see 20 summary forms.... and any more than that, well.. you can imagine. I thought about putting something inside SelectionChange() to check if user has stopped their selection.. but can't think of any.
This seems like a very simple matter, but somehow I can't figure it out..
My question, how to know if a user has stopped their selection in a datagridview ?
I still don't have enough points to just comment, so my answer would be I don't think you can reliably without adding another control (ie, button). You can't read the users mind and since the number of rows can be variable, how would you ever know? You could try something like if the cursor leaves the DGV but that would be frought with issues as well. While it would be an extra click for those just selecting 1 row, I still think having a "Get Summary" button would be the way to go. Sort of like when selecting items to compare - you can click any number of items and while they may show which items you've picked so far in another area, the comparison table doesn't appear until you click the Compare button.
From what I understand, you actually have two options.
Add a button
Since you can't figure out when the selection is done, just add a button that will call the Form you want to display, that way you are sure that it will display only when user asks for it.
Use a timer
Another option is to use a Timer, every time the selection changed, you reset the timer to one second (to keep the example simple).
And whenever the timer does a tick, you call the Form and stop the timer. That way it will trigger one second (or less) after the user made the selection and gives him one second to change it...
Honnestly, I think the button option is the best, as you give the power to your user. Maybe they will want to select some rows but don't want to see your form, as they will only copy it to paste it somewhere else...
I have a pretty simple form that brings up a certain record when the "caseNumber" is selected from the combobox. Although after a selection is made within the combobox, it will freeze the entire form on the record selected. I can't click on any other text boxes or buttons. I have to stop the debugger. No errors are thrown. I've read where this has happened to others, but no answers to the problem, that I can find.
There is no code behind it so far, as the form is bound to a dataset and should just bring up the rest of the information once the caseNumber is selected.
Changed the "Selected Value" dropbox to "none" on the data binding menu for the combobox.
Under DataBindings, go to Advanced and make sure DataSource update mode is on NOne
A lot of times this happens because there is a problem in the binding. Are you sure it's not binding the text value of the control(the combobobox) to the data?
The correct way to bind (under DataBindings, Advanced) was to bind it to the SelectedValue instead of Text.
Please let us know a little bit more how your combobox is binded.
I have this userform that i'm developing for my report formatting task. My whole code is finished, there are only 2 problems that i need to work on.
Making my VBA application work on every excel file that user choose
Exception Handling for ComboBoxes on my form.
(Edit: I hope trying to get attention of people who are interested in this question to another stackoverflow.com topic is not against forum rules)
You guys can reach first problem's topic from here: (There is already one suggestion but i'm little bit confused. So it would be super for alternative suggestions) http://bit.ly/VnF3cK
And about my second problem, when i click empty place of combobox, i can type whatever i want, but i want to restrict it, so users can only choose values [1-5] that i put inside of combobox. How can I achieve this?
In answer to your secondary question, you need to change the ComboBox's Style property to frmStyleDropDownList
How many times have we seen this type of selector:
List Box Selector http://geekswithblogs.net/images/geekswithblogs_net/dotNETvinz/MoveItemsListBox.jpg
I was just about to start creating this in a WinForms app, when I thought that others may have some ideas for doing this better. We need it to sort - so the right hand list will need up/down buttons. But this seems so old school. I love devexpress components, and was thinking of asking them if they would consider adding a component that handles this functionality with a slick UI.
I am thinking that a graphical representation of the objects, and a graphical representation of the listboxes - that would be a more intuitive way to move items around.
Has anyone seen an open source project like this?
If a CheckListBox won't suffice (and it usually will), then the "modern" approach would be to use a ListView or similar component with a "Transfer" column. Render the button inline in that column, one for each row, so that it only takes one click to move an item from one to the other.
You see this everywhere in Vista, usually with hyperlinks as opposed to buttons. Instead of clicking on an item and then choosing an action, you click the action at the item level.
I wouldn't go overboard with slickness as it can impair functionality, but the dual-listbox screen is definitely old-school.
Also, if there's a very large amount of data to manage, it helps to provide a progressive search at the bottom of one or both lists.
I have done this type of selection using (essentially) a single CheckListBox that displays each item as an image. Part of the image looks like a LED, which is on (bright) if the item is selected or off (dark) if it is not selected.
This works well if you have a reasonable amount of data to select from, and also works well in a multi-column format if you can predict that the options will have reasonably similar lengths.
Allow users to drag items in/out of list 2, and also drag to reorder in list2.
(All items dragged out of list2, and dropped anywhere outside the list, get put back into list 1, in their correct place in the list by alphabetical or natural order.)
You can merge the two list boxes into one with the help of groups (LVGF_GROUPID flag): one group for selected and one for not selected.
You can also implement group membership changes with drag-drop between them. This way single drag-drop can move an item into the other group at the appropriate position, saving most/all of the other buttons.
Additionaly the bottom of each group can have one pseudo item with help text (i.e. "Drag items here to...") that is visible only when relevant.