Hello FAST team/community members!
I am currently building out a project using FAST Element, web components, and Fluent-UI. I am trying to render something based on where two items are in an array.
I noticed that under the repeat directive there is an index property which will give the index of the current item inside a repeat block.
Is it possible to use the index property of repeat to also look ahead in the array?
Ex. if the current item is null, would it be possible to check index + 1 to see if the next item is null as well? Or would this have to be done outside of the repeat block with a check?
Thank you!
Yes, you can do that. However, bear in mind that the index lookup will not be "observed" because the observation system can't see when you access an array directly by index. e.g. myArray[index]. It will return the value just fine, but if what is at that index changes, the rendering engine won't know that and won't be able to trigger an update to the UI. However, if the index itself changes or any other observable changes, updates will work. Array index gets/sets are the one edge case that cannot be detected at present.
Related
I am currently working on a rogue-like game in GameMaker Studio 2 and i would like to have an item spawner where no items are repeated.
I have tried multiple different ideas of what i think would work, such as giving items and id variable and only spawning items which hasn't had it's id called, although it doesn't seem to work.
The code I have right now is basic, but that is because it's the only way I've been able to spawn an item, there is repeating items with what i have and i would like to stop that from happening.
Here is the Create code of the object:
// Items
var items = choose(
obj_homing,
obj_tracking,
obj_bounce,
obj_double_xp,
obj_shotgun,
obj_orbit,
obj_firefaster,
obj_scattershot,
obj_damageboost,
obj_explosive
);
instance_create_layer(x, y, "Items", choose(items));
I haven't had any actually crashes in the game, although the errors i have faced are multiple of the same object spawning twice when i would like items to not repeat.
One option is to modify the items array after each call to remove the spawned item, and re-initialize it as full only at the start of each game or when the array is empty.
The problem I'm seeing in looking through the Game Maker Language Documentation is that I cannot find a way to delete an object from an existing array and resize the array.
You're placing choose on both defining the var, and when creating the layer.
Now, I don't know exactly what choose does, but I assume it's choosing randomly a selection from the array.
So Items would only return a single chosen item from the array, maybe it's better to remove the choose function from the Items, and only decide that when creating the object.
So the Items should become an array:
var items = [
obj_homing,
obj_tracking,
obj_bounce,
obj_double_xp,
obj_shotgun,
obj_orbit,
obj_firefaster,
obj_scattershot,
obj_damageboost,
obj_explosive
];
Just save the random instance in a variable, then when you create a random instance, check if equals to the instance that you have created previously, and if it is, call again the function until the previous instance is different from the new generated instance.
If you want to spawn every item only once, how about changing the current spawned object in the array to "noone".
And at every spawn cycle, you would check, if the selected item is noone and if so, select the next item (array[i++]).
Also do not forget to randomize the seed, somewhere in the beginning of your game with randomize().
I am still learning, and looking for help on how to display a label based on one data-sources field value, being within another data-sources field value list.
I have one calculated table, displaying rows of documents within a folder, and wish to use a field representing the document number in that data-source, so that if it's ANYWHERE within another tables field it displays my label.
I've been trying to use projection as I think this is how to achieve it.
I can get it working based on both the current #datasouce.item.fieldnames but need it to base the calculation on all possible numbers in that tables field (Image below should make it easier to understand).
I expect that it has something to do with projections, but can't find anything within the learning templates or anywhere else to resolve the issue.
I think the following should work for you. For the 'Reserved' label have the following binding for the text property:
(#datasources.project_quotes.items..quotenumber).indexOf(#widget.datasource.item.Qnumber) !== -1 ? 'Reserved' : ''
I would suggest alternatively just to include a field in your calculated datasource and making the determination in your server script.
My friends, Could you please explain the concept of these methods to me? Normally, when I get a data I would use 'index' to refer to items in a model and specify roles via data attribute. I came across 'item' method today and the explanation of this method is "Returns the item for the given row and column if one has been set; otherwise returns 0." What are differences from 'index'+'data' method? Is it just a shortcut?
This is the documentation of 'item' method.
https://doc.qt.io/qt-5/qstandarditemmodel.html#item
Alternatively, this is the documentation of 'index' method.
https://doc.qt.io/qt-5/qstandarditemmodel.html#index
I'll try my best to explain it.
The item is like the actual widget you see in the view (it's not actually a widget, but I think it's a good way to think about it). It's what the user is actually seeing.
The index is more "behind the scenes." It's like a pointer to a position in the model.
An item can exist without an index. But a valid index cannot exist without an item. The item only associates with an index when it is put into a model. Otherwise, it's just an item that no one can look at.
Take an array as an example... It contains multiple "items". You specify which item from the array you want by providing a number, aka the index. Simply put, the index only exists when it is associated with an item in the array. But the item can exist outside of the array and be it's own thing without an index.
The QModelIndex was created to be a lightweight way to reference items in a model. Similar to the way you can use a number to represent an object stored in an array.
I'm using the new gcloud-java API (https://github.com/GoogleCloudPlatform/gcloud-java/tree/master/gcloud-java-datastore/src/main/java/com/google/cloud/datastore) for working with the Cloud Datastore. My specific question is on using GQL for pagination with cursors. I was able to page through the results one page at a time in the forward direction using cursors, but not having any luck with paging backwards.
Example Scenario:
Let's say I've 20 entities in a Kind with IDs 1 through 20. I have a page size of 5. Once I'm on the 3rd page (IDs 11 through 15), if I need to go one page back; i.e. retrieve IDs 6 through 10, what would be the correct GQL/sample code? Again, I prefer not to use offset with a number, but would like to use Cursors.
From what I can tell (actually tested), it looks like one needs to keep track of Start/End cursors for each page as they navigate in the forward direction, then use the saved cursors when there is a need to go back. I just want to make sure if this is the correct/only way or there is a simpler way to accomplish this.
Thanks in advance for your help.
If you add to your original query a sort by key (appended to the end of your "order by" clause), you should be able to reverse each property's sort order and use the latest cursor from your original query to get results in reverse.
Suppose you've iterated through some of the values from your forward query's QueryResults. You can call QueryResults's cursorAfter() method, which will return a cursor pointing right after the last result you saw from your original query. Now you can issue a new query (with the opposite sort order on each property, including the key property) using that cursor as the start cursor. You'll probably want to skip the first result, since it will be the last result you saw from the original query.
I've a problem with my Qt/interview application. I use QTreeView to display tree data. I implemented my own model based on QAbstractItemModel.
I get a following error prior to application crash. It happens often after I add new record.
Could You explain to me what is the meaning of this error. What is a QPersistentModelIndex ?
I'm not using QPersistentModelIndex in my code.
ASSERT failure in QPersistentModelIndex::~QPersistentModelIndex: "persistent model indexes corrupted"
Thanks.
QPersistentModelIndexes are (row, column, parent) references to items that are automatically updated when the referenced items are moved inside the model, unlike regular QModelIndex. For instance, if you insert one row, all existing persistent indexes positioned below the insertion point will have their row property incremented by one.
You may not use them directly, but QTreeView does, to keep track of expanded items and selected items, for example.
And for these persistent indexes to be updated, you have to call the functions QAbstractitemModel::beginInsertRows() and endInsertRows() around the actual row insertion(s) when you add new records.
See the end of the section about subclassing model classes for details: http://doc.trolltech.com/latest/qabstractitemmodel.html#subclassing
I found this method QAbstractItemModel::persistentIndexList and I'm
wondering what indexes it should return. All of them ?
Should this method return all nodes currently visible in the TreeView ?
That method returns only the indexes for which a QPersistentIndexModel was created and is still in scope (as a local variable, a class member, or in a QList<QPersistentIndexModel> for example).
Expanded or selected nodes are not necessarily currently visible, so you can't (and shouldn't anyway) assume anything about what these persistent indexes are used for.
You just have to keep them updated, and you only need to use persistentIndexList for big changes in the model, like sorting (see QTreeWidget internal model : QTreeModel::ensureSorted(link)), for smaller incremental changes you have all the beginXxxRows/beginXxxColumns and endXxxRows/endXxxColumns methods.