bit new to asp.net so bear with me. I have a dropdown that is being populated from a SqlDataSource. This dropdown's selected value is used as a parameter in another SqlDataSource for my results grid.
Problem is my dropdown is not being populated with anything until after page_load. This is causing an issue because I'm calling a method that uses the dependent SqlDataSource in the page_load, and it blows up because one of its parameters is null.
I've tried the page_prerender as well, and the drop down is still not populated by then. Any ideas on what method in the life cycle I can use, or a way to populate the SqlDataSource controls earlier?
Related
I'm using and loving react-hook-form. I've run across an issue where I have a list of items (let's say in the left column), then when you click on any item it will display an edit component for the selected item in the right column. The issue is when I switch between items, nested array values don't seem to update the data correctly.
I think I understand that because a new edit component isn't created for each parent item (I'm just passing the selected index down) the nested useFieldArray in the edit component still references the first parent item. If that's the case, I'm not exactly sure how to make sure a new useFieldArray is created for each item that gets selected.
Here's a codesandbox replicating the issue:
https://codesandbox.io/s/dreamy-brattain-r74lx
Any help is much appreciated.
I think you can just map over the childItems prop of your watched item inside your <Details /> component instead of using fields. As you are using watch the <Details /> will be re-rendered after appending a new child item.
If your <Details /> component should get more complex i would also suggest to use useWatch here instead of passing watch. Check this quote from the documentation for useWatch:
Behaves similarly to the watch API, however, this will isolate
re-rendering at the component level and potentially result in better
performance for your application.
Here is an example using useWatch:
I just ran into an issue that I have never noticed before and I want to know if this is something isolated to my current project for some reason or if this is an issue that I need to panic about and check every one of my applications and correct right away.
I have two drop downs on the same page using the same select list.
ex. HomeCity and CurrentCity
both populated from the same list of cities. Therefore in code both populated from the same IEnumerable<selectListItem>
It turns out that if the second value on the page is null (in the view model) then instead of defaulting to the optionLabel it defaults to whatever the first value is.
This issue is much exasperated when (as I often do) you try to cache the SelectList. Not only is the next item on the same page set to the wrong value, but the selected item gets changed in the cache (which is so strange because you would imagine that the cache serializes the values and give you a copy.
So my question is twofold.
is this the usual functionality or did I trigger this weird behavior somehow?
What is the recommended way to avoid this? Would I need to do a deep clone of my select list between dropdowns?
We are facing a problem with dynamic columns. We have a table where columns depend on some filters previouosly selected. When you enter the page you can select year and some other criteria, and with these values we render the table. Our problem is that columns may vary when you select different criteria, and this is a problem because c:forEach is not so much dynamic.
If you look at the example provided in IceSoft Wiki you can see something similar to what we have in our code (but our code is much more complicated):
http://www.icesoft.org/wiki/display/ICE/DataTable+Dynamic+Columns
The problem comes with this sentence:
<c:forEach items="#{backing.columns}" var="colModel">
backing.columns is static. But if you change its number of elements (in this example it makes no sense because values in "columns" List match to properties in Task class, but if you are printing a List instead of List) you have a problem, as described here:
http://drewdev.blogspot.com.es/2008/08/cforeach-with-jsf-could-ruin-your-day.html
We've tried to recreate component list when we change columns with:
component.getChildren().clear(); //component is of UIComponent type
But didn't work. Also we've tried restoring view from context in a PhaseListener, and no positive results. And we've run out of ideas.
Any idea (or solution :D) would be appreciated. And if someone need more specific code, just ask.
TIA.
PS: This question is also posted in ICEFaces Forum (http://www.icesoft.org/JForum/posts/list/0/21842.page#76787), and I will update with solution (if any) both places.
We've solved the problem, as we've been suggested at IceSoft Forum, redirecting navigation to the same page in order to get a completely new component tree. For this you need your state to be in a bean that will survive that, but since our backing beans are usually viewscoped this is not a problem. To achieve this, we've changd valueChangeListener method that was changing the list behind the c:foreach and used an action method, and in this action method we're returning null as navigation rule to get the page reload.
See more at: http://www.icesoft.org/JForum/posts/list/21842.page#sthash.sXtPazmS.dpuf
On Telerik demo site we can see an example of how to implement kind of functionality: "check all checkbox in a grid's column". But in my case it has 2 disadvantages:
It didn't check all checkbox on all pages.
It didn't save a state of checkboxes on different pages.
Is anybody know how to resolve these issues? Thanks in advance.
As long as I know there's no built-in functionality to do so. The same problem happens when you select records on page one and change to page two, you loose whatever you selected before.
To achieve that functionality you have 2 options (I've used both on previous projects)
1) On each check make an Ajax call to one of your controllers and store whatever you selected on a Session Variable (This can be inefficient if you have a lot of records)
2) Create a javascript variable and store your selections there, and send back to the controller using a json variable or a comma separated values string
As I said, I've used both approachs so it depends on if this works for you or not
Hope it helps
I can't test this, so I'm not 100% sure, but looking at Telerik's example, one reason it's not persisted is because every "page" of the grid requires a postback, and in the controller action result method, they aren't passing in the model (or view model) for the items that are bound to the grid, they're only returning that list of items back to the view, so it will never "save" which items are checked/selected and which ones aren't. You should be able to get around this by making your view model a parameter into the HttpPost action result method and then passing that list back to the view after the post so that it retains which items are selected instead of creating a new one. This won't solve the issue with not selecting all the items, but it should at least retain which ones are selected throughout the pages. I think the reason for it not working with all items is it can only select the ones that are actually being displayed at the time. You may want to do a post (or ajax) to select "all" items.
One of the major reasons for using paging in grids is so that you don't have to retrieve all of the data from the data store and generate a lot of HTML to push to the client.
It's been my experience that most users understand that a "select all" check box only checks the items on the current page. I've not seen a site where checking such a check box would actually check all records, even those I can't see.
If you have an action which will affect more than the current page of records, I would suggest that you add a button which clearly indicates that the action will affect all records, then send a command to your data layer which will perform that action. This will perform better (you don't have to send a potentially long list of ids across the wire) and allow users to understand the repercussions of their action.
The contents of my MVCContrib grid come from the Model on a strongly typed View. When a post is made, the contents of the grid are not in the model object when it returns to the controller. I can see that this is because the grid renders as just a table with text in cells. Is there something I can do so that when the post occurs, the list data I sent down to the grid comes back in the post?
You can use TempData to persist this information server side. The information in TempData will persist for one request. I do not really like this option however.
Can you not repopulate your model from the db? If the user is not changing the information why do you need to post back all the same unchanged information? Just grab it again from where you got it before.
If you want to recreate the model as it was serialised into the grid, you will have to embed correctly named form elements within the grid ( or maybe outside the grid ) and within the same form as the one containing the button that is posting back to the action where you want your Model recreated.
While this is doable, you are essentially recreating __VIEWSTATE, and that defeats much of the joy of working with MVC ( read "it's an ugly hack and you should uninstall your IDE for even thinking it").
It is hard to point you in the right direction without having a better understanding of the scenario you are trying to solve. The usual workflow in these situations is
get the model
generate the page
record any changes to the model in a
form on the page
submit the changes to an action
get the model again
use TryUpdate to persist the changes
from the post into the model
If you are suffering performance issues ( you have proved you've got a perf problem right? You aren't optimising prematurely?), address them where they occur ( i.e. caching in your data access ), rather than bending MVC in ways it really shouldn't be.