I'm using BehaviorSubject and it's emitting back last item on subscription as expected. However, sometimes, data is not changed and and with new listen event will be triggered back with last emitted item.
Would be nice to use distinct to remove duplicated data. However on new listen event stream recreated and doesn't have history. Besides that last item. Any sane solution to handle such situation? To summarize, how we can keep using BehaviorSubject, but filter/distinct last item?
final _subject = BehaviorSubject<String>();
get Stream<String> distinctSubject => _subject.stream.distinct();
and you probably shouldn't do listen() too often either
Create subsclass of BehaviourSubject and override add method, so you could store all added items in set variable and check for _set.containts(newItem);
Related
I have a plannerTask and in its Details it has a CheckList. I use it to programatically insert CheckListItems in it, and it all works like a charm when inserting or retrieving the tasks.
My problem arrives when I am going to insert a new CheckListItem and the CheckList already has 20 items. It returns a MaximumChecklistItemsOnTask (because it is forbidden to insert more than 20 items in a check list).
Solution could be to remove the oldest item, but I am not able to do it. I have tried this:
var elementToRemove = oldDetails.Checklist.Where(c => c.Value.IsChecked).OrderBy(c => c.Value.LastModifiedDateTime).First();
oldDetails.Checklist = oldDetails.Checklist.Where(c => c.Value.LastModifiedDateTime <> elementToRemove.Value.LastModifiedDateTime);
But it throws a casting error in the second line:
Unable to cast object of type
'WhereEnumerableIterator1[System.Collections.Generic.KeyValuePair2[System.String,Microsoft.Graph.PlannerChecklistItem]]'
to type 'Microsoft.Graph.PlannerChecklistItems'.
Which is the right way to remove the oldest element from the ChecklistItem?
UPDATE:
In first place I retrieve a plannerTask from the server. Then I get the details from this plannerTask. So oldDetails is a plannertaskdetails object (https://learn.microsoft.com/en-us/graph/api/resources/plannertaskdetails?view=graph-rest-1.0). Inside the plannertaskdetails object (oldDetails), I have the plannerchecklistitems object (oldDetails.Checklist): https://learn.microsoft.com/en-us/graph/api/resources/plannerchecklistitems?view=graph-rest-1.0.
If plannerchecklistitems were just a List, it would be as easy as list.Remove(item), but it is not a normal list, and that is why I am not able to remove the item.
UPDATE 2:
I have found this way to remove the item from oldDetails:
oldDetails.Checklist.AdditionalData.Remove(elementToRemove.Key)
But, the the way I send the changes to the server is this:
await graphClient.Planner.Tasks(plannerTask.Id).Details.Request().Header("If-Match", oldDetails.GetEtag).UpdateAsync(newDetails)
As it is a PATCH request (not a PUT one), I only have in newDetails the records that have changed, it is, the new records. How could I specify there that a record has been deleted from the list? Sorry if my English is not good enough to express myself properly, but what I mean is that newDetails is not the full list, it only contains the records that must be added and I do not know how to specify in that request that one record must be deleted.
When I call this observe function from in my viewcontroller, the .childadded immediately returns a object that was already stored instead of has just bin added like .childadded would suspect.
func observe(callback: RiderVC){
let ref = DBProvider.Instance.dbRef.child("rideRequests")
ref.observe(DataEventType.childAdded) { (snapshot: DataSnapshot) in
if let data = snapshot.value as? NSDictionary {
let drive = cabRide(ritID: ritID, bestemming: bestemming,
vanafLocatie: vanaf, taxiID: taxiID, status: status)
print(drive)
callback.alertForARide(title: "Wilt u deze rit krijgen?", message: "Van: \(vanaf), Naar: \(bestemming)", ritID: ritID)
}
}
}
When I try this function with .childchanged, I only get a alert when it is changed like it suppose to do, but when doing .chiladded, it just gets all the requests out of the database and those requests were already there.
When I add a new request, it also gives an alert. So it works, but how can I get rid of the not added and already there requests?
Does anybody know this flaw?
This is working exactly as promised. From the documentation:
Retrieve lists of items or listen for additions to a list of items.
This event is triggered once for each existing child and then again
every time a new child is added to the specified path. The listener is
passed a snapshot containing the new child's data.
That might seem weird at first, but this is generally what most developers want, as it's basically a way of asking for all data from a particular branch in the database, even if new items get added to it in the future.
If you want it to work the way you're describing, where you're only getting new items in the database after your app has started up, you'll need to do a little bit of work yourself. First, you'll want to add timestamps to the objects you're adding to the database. Then you'll want to do some kind of call where you're asking to query your database by those timestamps. It'll probably look something like this:
myDatabaseRef.queryOrdered(byChild: "myTimestamp").queryStarting(atValue: <currentTimestamp>)
Good luck!
I'm programmatically pushing an object (using pushObject) into a list that is sortable. My problem becomes that if I try $(selector).sortable('refresh') or $(selector).sortable('serialize') the serialize doesn't contain the recently added dom item. I can console.log($(selector)) and it seems to know that the dom item has been added though.
My original thought is there an event to watch for once pushObject has finished? Or a callback?
Is there an event to watch for on pushObject?
Easiest way to do this is add an observer that fires when the list length has changed. But probably that's not gonna be enough in this case.
It sounds like this is a timing issue. If you try to call refresh right after pushObject (or even in an observer) the refresh code is going to run before the dom has been updated.
The trick is to make sure you are calling $(selector).sortable('refresh') after the new elements have been written to the dom. That could be from a didInsertElement hook on the dom item's view or from an observer, but as #Luke reminded me in comments best way to do it is by scheduling refresh to run after render has completed. Something like:
Em.run.schedule('afterRender', this, this.refreshSortable)
I'm building a messaging application. I update the badge count in the database via a sqlite trigger whenever any operation like insert/delete/read message happens.
Currently, though the value update in the DB happens asynchronously, I have no way to get notified about when the value changes in my application and hence am polling periodically.
Is there some way to setup an observer on a database value/publish some notification when a given value changes?
I know that I can do this easily by first updating the badge count in an in-memory property and then persisting the changes to the DB; but I am not very inclined to do this, since there are too many entry points for this value to change, and I don't want to add a SET property everywhere.
One possible option would be to define a trigger that is only called when this specific value in the database is updated. The trigger should then make a call to a user defined function you create in your app. You use the sqlite3_create_function function to add your own function to SQLite. Your trigger would like something like:
CREATE TRIGGER some_trigger_name
AFTER UPDATE OF some_column ON some_table
FOR EACH ROW BEGIN
SELECT my_custom_fuction();
END;
If needed, you can pass 1 or more arguments to your function.
Though that this might not be an option for you, Core Data does this well.
I want to delete items and refresh it. I have been trying for 2 days, no luck.
listField.delete(index) doesn't work.
If you can provide me appropriate solution, I will give you all of my reputation.
You'll probably have to override it to remove the item from your data backing the list, and then call listField.setSize(newSize). Since it doesn't know what sort of data structure you are using to push elements into it, it can't be sure how to remove them.
For example, if you have a Vector that stores your data, override delete() to remove the element, and then call setSize(vector.size()). If your ListFieldCallback is stored somewhere else, just make a wrapper call to a similar delete() method in your callback.