I currently have an array of strings. The user will scroll down, and I want to know how far they went down the list.
Is there anyway to do this, without using the indexPath.row feature from tableView/collectionView AND without knowing the string? (String is currently random data pulled from my database)
var name = ["jfiwojf", "awjefoeij", "awjfioe", "awjefoi"]
You can check your table view property indexpathsforvisiblerows. This will return an array with the index of the cells that are visible to the user at the time you call that property. You just need to check the which element of your collection is represented by the last index returned from it.
If are using a collection view you can check its indexpathsforvisibleitems property. Note that the result of this method is not sorted.
I will suggest you to do some things like set an index
You can do it like so
var index = 0
func didTapped(index: Int) {
index = index
}
Then you call when your user selected a row or select an item.
Related
I am storing a simple list of id's as GUIDs in Realm, but would like the ability to delete an object at a particular index position.
So for example, I want to remove 04b8d81b9e614f1ebb6de41cb0e64432 at index position 1, how can this be achieved? Do I need to add a primary key, or is there a way to remove the item directly using the given index position?
Results<RecipeIds> <0x7fa844451800> (
[0] RecipeIds {
id = a1e28a5eef144922880945b5fcca6399;
},
[1] RecipeIds {
id = 04b8d81b9e614f1ebb6de41cb0e64432;
},
[2] RecipeIds {
id = cd0eead0dcc6403493c4f110667c34ad;
}
)
It seems like this should be a straightforward ask, but I can't find any documentation on it. Even a pointer in the right direction would do.
Results are auto-updating and you cannot directly modify them. You need to update/add/delete objects in your Realm to effect the state of your Results instance.
So you can simply grab the element you need from your Results instance, delete it from Realm and it will be removed from the Results as well.
Assuming the Results instance shown in your question is stored in a variable called recipes, you can do something like the following:
let recipeToDelete = recipes.filter("id == %#","04b8d81b9e614f1ebb6de41cb0e64432")
try! realm.write {
realm.delete(recipeToDelete)
}
Using Firebase and Swift SDK
I just started with Firebase and wanted to display a list of Conversations ordered by last_update. The following query works fine :
let query = Database.database().reference().child("chat").child("channels").queryOrdered(byChild: "last_update")
query.observe(DataEventType.childAdded) { (snapshot: DataSnapshot) in
if let value = snapshot.value as? [String: Any?] {
log.debug("added channel: \(snapshot.key) : \(value)")
//add object to array, insertRow in tableview
}
}
The first time my view is loaded, each item arrives in the correct order specified by the query, so the display is ok. But if I create a new channel, it does appear at the end of the tableview, because I just add it at the end of the array and just call insertRow on my table view. My question is : is there any mecanism that give us the new inserted position of the DataSnapshot ?
Same question for DataEventType.childMoved : we get to know that a snapshot has moved, but how to know where it has moved ??
I finally end up using FirebaseUI, especially the submodule FirebaseDatabaseUI (see the github repo here)
They provide a FUITableViewDataSource, you just create a query and pass it to it, it will handle everything like sorting etc. I also used FUIArray, which is simply an array backed by a query, with a delegate for added / deleted / moved / update events (and proper indexes).
I am very new to MongoDB (only got started out of interest last week). I am trying to figure out something and I'm not entirely sure of the terminology to go about searching for it. So I decided to make a SO question.
I created a collection called Students. Students has the fields id, name, undergrad(which is a boolean), classes(which is an array) and units(which is 3 times the number of classes the student has).
Now, I wanted to see how I could perform actions on a particular field of Students. What I did was, inserted a couple documents and purposefully did not include the units field. And I wanted to $set the units field forEach document/student that did not have the field. I did the following:
var studentDoc = db.students.find({units: {$exists:false}})
studentDoc.forEach(function(stu){
db.student.update({_id:stu._id}, {$set:{units:{$size:"$classes"}}})
}
)
Question 1: Is what I've done even remotely correct?
Question 2: When I type studentDoc after setting the var studentDoc, it doesn't print anything. But when I write
var studentDoc = db.students.find({units:{$exists:false}}).toArray()
it prints studentDoc as an array but still doesn't seem to do anything in the forEach loop.
Question 3: How do I $set the units field as 3 * (size of classes array)
I hope I have been clear in my question. I have tried searching on the MongoDB docs and google, but haven't had any luck (probably because of my lack of knowledge to search for the correct things).
Any help would be great! You can even point me in the right direction, and that'll be great!
Thank you in advance for all your help!!
I'm not sure why foreach not getting in. You can do the same with below working code.
for(i=0;i<studentDoc.length();i++){
var stud_id = studentDoc[i]._id;
var doc = db.students.findOne({"_id":stud_id})["classes"];
if(doc){
var len = doc.length;
db.students.update({"_id":stud_id},{$set:{"units":len*3}})
}
}
As far as I know, You can't use $size:"$" queries in update statement. you will get error like below:
The dollar ($) prefixed field '$size' in 'units.$size' is not valid for storage.
The return value of db.collection.find() is cursor.
In the mongo shell, if the returned cursor is not assigned to a variable using the var keyword, the cursor is automatically iterated up to 20 times to access up to the first 20 documents that match the query. To iterate manually, assign the returned cursor to a variable using the var keyword. So
var studentDoc = db.students.find({units: {$exists:false}})
You should iterator studentDoc manually.
Whereas, the cursor.toArray() returns an array that contains all the documents from a cursor. The method iterates completely the cursor, loading all the documents into RAM and exhausting the cursor. Thus
var studentDoc = db.students.find({units:{$exists:false}}).toArray()
it prints studentDoc as an array.
If you want to use forEach, here is cursor.forEach().
db.students.find({units:{$exists:false}}).forEach()
var studentDoc = db.students.find({units: {$exists:false}})
here studentDoc is a cursor, it's not printable.
you can use forEach
studentDoc.forEach(printjson);
or iterator the cursor
while (studentDoc.hasNext()) {
printjson(studentDoc.next());
}
This may be a basic question, but it's my first, so please be kind :-).
I have a sap.m.table with two models, one model with transaction data (trxModel) and another model that is used to display a sap.m.select list (reasonCodeModel). The table model is set to trxModel.
The selected value key from the dropdown needs to update a value (ReasonCodeID) in the trxModel when a value from the reason code list is selected.
I can retrieve the selected key in the change event as so
var selKey = evt.getParameter("selectedItem").getKey();
Is there a simple way to find the trxModel relevant model path from the table row Select list value I've just modified? Or is it possible to bind the ReasonCodeID from the trxModel to the ReasonCodeID field in the reasonCodeModel?
Just an extra piece of info, The current row is selected and is accessible
var selItem = dtlTable.getSelectedItem();
2nd question and I guess could be kind of related, is there a way of getting the table model path based on the selected item (highlighted row) of the table? And vice a versa?
More details on Select & Table binding.
var tabTemplate = new sap.m.ColumnListItem(
{
::
new sap.m.Select(
"idReasonCodeSelect",
{
enabled : false,
change : function(evt) {
oS4View.getController().changeReasonCodeSel(evt);
}
}
),
Bind the resource code Select to the Table
// bind the reason codes to the reason code model
sap.ui.getCore().byId("idReasonCodeSelect").setModel(
oReasonCodeModel);
sap.ui.getCore().byId("idReasonCodeSelect").bindAggregation("items", "/results",
new sap.ui.core.Item({
key : "{ReasCodeID}",
text : "{ReasCodeDesc}"
}));
Per Qualiture comment, how do I bind the Select key to the table model ReasonCodeID value?
I found an approach to tackle the first part of my question above
From the change function on the Select, I can find the path of the table model using the following.
var path = evt.getSource().getParent().getBindingContext().sPath;
2nd Update:
On the selectionChange event on the table, there's a couple of options to find the associated model path or model content.
// find the model path
oModelPath = selItem.getBindingContext().getPath();
// model values
oItem = oEvent.getParameter("listItem").getBindingContext().getObject();
So my only remaining issue, While I loop through the table model results (trxModel) and I want the Select List (using setSelectedKey) to reflect the ReasonCodeID value in the trxModel.
I'm new to Couchbase and am struggling to get a composite index to do what I want it to. The use-case is this:
I have a set of "Enumerations" being stored as documents
Each has a "last_updated" field which -- as you may have guessed -- stores the last time that the field was updated
I want to be able to show only those enumerations which have been updated since some given date but still sort the list by the name of the enumeration
I've created a Couchbase View like this:
function (doc, meta) {
var time_array;
if (doc.doc_type === "enum") {
if (doc.last_updated) {
time_array = doc.last_updated.split(/[- :]/);
} else {
time_array = [0,0,0,0,0,0];
}
for(var i=0; i<time_array.length; i++) { time_array[i] = parseInt(time_array[i], 10); }
time_array.unshift(meta.id);
emit(time_array, null);
}
}
I have one record that doesn't have the last_updated field set and therefore has it's time fields are all set to zero. I thought as a first test I could filter out that result and I put in the following:
startkey = ["a",2012,0,0,0,0,0]
endkey = ["Z",2014,0,0,0,0,0]
While the list is sorted by the 'id' it isn't filtering anything! Can anyone tell me what I'm doing wrong? Is there a better composite view to achieve these results?
In couchbase when you query view by startkey - endkey you're unable to filter results by 2 or more properties. Couchbase has only one index, so it will filter your results only by first param. So your query will be identical to query with:
startkey = ["a"]
endkey = ["Z"]
Here is a link to complete answer by Filipe Manana why it can't be filtered by those dates.
Here is a quote from it:
For composite keys (arrays), elements are compared from left to right and comparison finishes as soon as a element is different from the corresponding element in the other key (same as what happens when comparing strings à la memcmp() or strcmp()).
So if you want to have a view that filters by date, date array should go first in composite key.