I want to check if the node is already exist in the graph before adding a new node.
I tried to do it using a foreach loop.But it didnt work.
boolean returnVal = false;
for (Node node : displayGraph) {
if (node.getId().equals(n.getId())){
returnVal = true;
}
else{
returnVal =false;
}
}
I want to retrieve true if the node is already exist on the graph
Just check what Graph.getNode(String) returns. If no node with that string id exist, then null is returned:
boolean returnVal = displayGraph.getNode(n.getId()) == null ? false : true;
Related
LinkedListA = 3->4->5
LinkedListB = 12->6->9
I am simply trying to add linkedlistB at the end of the first linkedlistA.
I am not able to figure out Why the final while loop is able to print
the complete linkedlistA WITH all the nodes added from linkedlistB!
public static void joinLists(Node headA, Node headB)
{
Node currentA = headA;
Node currentB = headB;
while( currentA.nextLink != null )
{
currentA = currentA.nextLink;
}
Node newElement = currentB;
currentA.nextLink = newElement; //there is not loop here as you can see to keep updating the list with newElement taking new currentB value
currentB = currentB.nextLink;
currentA = headA;
while(currentA != null)
{
System.out.println(currentA.data);
currentA = currentA.nextLink; //output 3->4->5->12->6->9 How!?
}
}
My initial logic was doing simply this:-
public static void joinLists(Node headA, Node headB)
{
Node currentA = headA;
Node currentB = headB;
while (currentB != null)
{
currentA = head;
while( currentA.nextLink != null )
{
currentA = currentA.nextLink;
}
Node newElement = currentB;
currentA.nextLink = newElement;
currentB = currentB.nextLink;
}
currentA = headA;
while(currentA != null)
{
System.out.println(currentA.data);
currentA = currentA.nextLink;
}
}
But this doesn't seem to work!
But before that tell me how the first code seems to work?
You made the last node in A (the 5) point to the first node in B (the 12), which exactly corresponds to your output. You don't need a loop because the connections are distributed: each node only knows where the next node is. In attaching B to the end of A, only 1 link changes: the one you changed.
The first loop appends the list headB at the end of list headA.
public static Node joinLists(Node headA, Node headB)
{
if (headA == null)
{
headA = headB;
}
else
{
Node currentA = headA;
while (currentA.nextLink != null)
{
currentA = currentA.nextLink;
}
currentA.nextLink = headB;
}
Node current = headA;
while (current != null)
{
System.out.println(current.data);
current = current.nextLink;
}
return headA;
}
Then the printing loop would work.
In your second loop you tried something out (curretnA = head;).
Less variables will make understanding easier, as shown here.
One must use the return value for the joined list, as headA could be null.
LinkedList Data Structure work by the principal of ValueByReference Logic, that means, each node of linkedList can be stored anywhere in the memory location, we are just linking each node by mapping memory address to "Node.next" field
In First logic Code
Node newElement = currentB;
currentA.nextLink = newElement;
currentB = currentB.nextLink;
Your directly mapping headB pointer to last element in LinkedListA, so it similar to connecting each node in LinkedList.
Here's my pagination/infinite scrolling scenario:
Load the initial N with startAt().limit(N).once('value'). Populate a list items.
On scroll, load the next N. (I pass a priority to startAt() but that's tangential.)
When a new item is added, I'd like to pop it to the top of items.
If I use a .onChildAdded listener for step 3, it finds all the items including those I've already pulled in thus creating duplicates. Is there a better way?
Another method would be to use the .onChildAdded listener for the initial N in step 1 instead of .once, but when the initial N items come in I do items.add(item) to sort one after the other as they are already in order, but with the new one that comes in after the fact I need to somehow know it's unique so I can do items.insert(0, item) to force it to the top of the list. I'm not sure how to set this up, or if I'm off the mark here.
EDIT: Still in flux, see: https://groups.google.com/forum/#!topic/firebase-talk/GyYF7hfmlEM
Here's a working solution I came up with:
class FeedViewModel extends Observable {
int pageSize = 20;
#observable bool reloadingContent = false;
#observable bool reachedEnd = false;
var snapshotPriority = null;
bool isFirstRun = true;
FeedViewModel(this.app) {
loadItemsByPage();
}
/**
* Load more items pageSize at a time.
*/
loadItemsByPage() {
reloadingContent = true;
var itemsRef = f.child('/items_by_community/' + app.community.alias)
.startAt(priority: (snapshotPriority == null) ? null : snapshotPriority).limit(pageSize+1);
int count = 0;
// Get the list of items, and listen for new ones.
itemsRef.once('value').then((snapshot) {
snapshot.forEach((itemSnapshot) {
count++;
// Don't process the extra item we tacked onto pageSize in the limit() above.
print("count: $count, pageSize: $pageSize");
// Track the snapshot's priority so we can paginate from the last one.
snapshotPriority = itemSnapshot.getPriority();
if (count > pageSize) return;
// Insert each new item into the list.
// TODO: This seems weird. I do it so I can separate out the method for adding to the list.
items.add(toObservable(processItem(itemSnapshot)));
// If this is the first item loaded, start listening for new items.
// By using the item's priority, we can listen only to newer items.
if (isFirstRun == true) {
listenForNewItems(snapshotPriority);
isFirstRun = false;
}
});
// If we received less than we tried to load, we've reached the end.
if (count <= pageSize) reachedEnd = true;
reloadingContent = false;
});
// When an item changes, let's update it.
// TODO: Does pagination mean we have multiple listeners for each page? Revisit.
itemsRef.onChildChanged.listen((e) {
Map currentData = items.firstWhere((i) => i['id'] == e.snapshot.name);
Map newData = e.snapshot.val();
newData.forEach((k, v) {
if (k == "createdDate" || k == "updatedDate") v = DateTime.parse(v);
if (k == "star_count") v = (v != null) ? v : 0;
if (k == "like_count") v = (v != null) ? v : 0;
currentData[k] = v;
});
});
}
listenForNewItems(endAtPriority) {
// If this is the first item loaded, start listening for new items.
var itemsRef = f.child('/items').endAt(priority: endAtPriority);
itemsRef.onChildAdded.listen((e) {
print(e.snapshot.getPriority());
print(endAtPriority);
if (e.snapshot.getPriority() != endAtPriority) {
print(e.snapshot.val());
// Insert new items at the top of the list.
items.insert(0, toObservable(processItem(e.snapshot)));
}
});
}
void paginate() {
if (reloadingContent == false && reachedEnd == false) loadItemsByPage();
}
}
Load the initial N with startAt().limit(N).once('value'). Populate a list items.
On the first run, note the first item's priority, then start an onChildAdded listener that has an endAt() with that priority. This means it'll only listen to stuff from there and above.
In that listener, ignore the first event which is the topmost item we already have, and for everything else, add that to the top of the list.
Of course, on scroll, load the next N.
EDIT: Updated w/ some fixes, and including the listener for changes.
I have difined my flow as:
builder.id("", PublisherBean.PUBLISHER_FLOW_NAME);
builder.viewNode("list", "/pages/publishers.xhtml");
builder.viewNode("details", "/pages/publishers-details.xhtml");
builder.viewNode("deleted", "/pages/publishers-deleted.xhtml");
builder.viewNode("form", "/pages/publishers-form.xhtml");
builder.viewNode("exit", "/index.xhtml");
builder.methodCallNode("invoke-update")
.expression("#{publisherBean.update()}")
.defaultOutcome("details");
builder.methodCallNode("switch-fail")
.defaultOutcome("invoke-publishers")
.expression("#{publisherBean.switchFail()}");
builder.switchNode("proceed-action-request")
.defaultOutcome("switch-fail")
.switchCase()
.condition("#{publisherBean.actionType.ifEdit()}").fromOutcome("form");
builder.switchNode("go-for-it")
.defaultOutcome("switch-fail")
.switchCase()
.switchCase()
.condition("#{publisherBean.actionType.ifEdit()}").fromOutcome("invoke-update");
as you can see, there is two switch nodes. First directs to a View Node, second one is trying to direct to a Method Call Node.
First one works fine, however second is giving me a headache. Second one is giving me an error
Unable to find matching navigation case with from-view-id '/pages/publishers-form.xhtml' for action '#{publisherBean.proceed()}' with outcome 'proceed-form'.
proceed function is just
public String proceed() {
LOG.log(Level.OFF, "Form proceed in action type {0}", actionType);
return "go-for-it";
}
Logged info confirms, that publisherBean.actionType.ifEdit() returns true, however that fact is ignored. If i change outcome from invoke-update to form or any other View Node id, then it "works fine".
Is it i'm doing something wrong, or Method Call Node cant be used as an outcome to a Switch Node?
I run into this issue too. In my case the problem is in calling Method Call Node after another Method Call Node.
I invesigated it a bit and found a problem in: com.sun.faces.application.NavigationHandlerImpl.synthesizeCaseStruct method. This method is used to determine where to go from methodCallNode or switchCallNode and it only looks at viewNodes and returnNodes.
private CaseStruct synthesizeCaseStruct(FacesContext context, Flow flow, String fromAction, String outcome) {
CaseStruct result = null;
FlowNode node = flow.getNode(outcome);
if (null != node) {
if (node instanceof ViewNode) {
result = new CaseStruct();
result.viewId = ((ViewNode)node).getVdlDocumentId();
result.navCase = new MutableNavigationCase(fromAction,
fromAction, outcome, null, result.viewId,
flow.getDefiningDocumentId(), null, false, false);
} else if (node instanceof ReturnNode) {
String fromOutcome = ((ReturnNode)node).getFromOutcome(context);
FlowHandler flowHandler = context.getApplication().getFlowHandler();
try {
flowHandler.pushReturnMode(context);
result = getViewId(context, fromAction, fromOutcome, FlowHandler.NULL_FLOW);
// We are in a return node, but no result can be found from that
// node. Show the last displayed viewId from the preceding flow.
if (null == result) {
Flow precedingFlow = flowHandler.getCurrentFlow(context);
if (null != precedingFlow) {
String toViewId = flowHandler.getLastDisplayedViewId(context);
if (null != toViewId) {
result = new CaseStruct();
result.viewId = toViewId;
result.navCase = new MutableNavigationCase(context.getViewRoot().getViewId(),
fromAction,
outcome,
null,
toViewId,
FlowHandler.NULL_FLOW,
null,
false,
false);
}
}
} else {
result.newFlow = FlowImpl.SYNTHESIZED_RETURN_CASE_FLOW;
}
}
finally {
flowHandler.popReturnMode(context);
}
}
} else {
// See if there is an implicit match within this flow, using outcome
// to derive a view id within this flow.
String currentViewId = outcome;
// If the viewIdToTest needs an extension, take one from the currentViewId.
String currentExtension;
int idx = currentViewId.lastIndexOf('.');
if (idx != -1) {
currentExtension = currentViewId.substring(idx);
} else {
// PENDING, don't hard code XHTML here, look it up from configuration
currentExtension = ".xhtml";
}
String viewIdToTest = "/" + flow.getId() + "/" + outcome + currentExtension;
ViewHandler viewHandler = Util.getViewHandler(context);
viewIdToTest = viewHandler.deriveViewId(context, viewIdToTest);
if (null != viewIdToTest) {
result = new CaseStruct();
result.viewId = viewIdToTest;
result.navCase = new MutableNavigationCase(fromAction,
fromAction, outcome, null, result.viewId,
null, false, false);
}
}
return result;
}
I'm using select2 with Bootstrap 3.
Now I would like to know whether it is possible to display all optgroup items if the search matches the optgroup name while still being able to search for items as well. If this is possible, how can I do it?
The above answers don't seem to work out of the box with Select2 4.0 so if you're hunting for that, check this out: https://github.com/select2/select2/issues/3034
(Use the function like this: $("#example").select2({matcher: modelMatcher});)
function modelMatcher (params, data) {
data.parentText = data.parentText || "";
// Always return the object if there is nothing to compare
if ($.trim(params.term) === '') {
return data;
}
// Do a recursive check for options with children
if (data.children && data.children.length > 0) {
// Clone the data object if there are children
// This is required as we modify the object to remove any non-matches
var match = $.extend(true, {}, data);
// Check each child of the option
for (var c = data.children.length - 1; c >= 0; c--) {
var child = data.children[c];
child.parentText += data.parentText + " " + data.text;
var matches = modelMatcher(params, child);
// If there wasn't a match, remove the object in the array
if (matches == null) {
match.children.splice(c, 1);
}
}
// If any children matched, return the new object
if (match.children.length > 0) {
return match;
}
// If there were no matching children, check just the plain object
return modelMatcher(params, match);
}
// If the typed-in term matches the text of this term, or the text from any
// parent term, then it's a match.
var original = (data.parentText + ' ' + data.text).toUpperCase();
var term = params.term.toUpperCase();
// Check if the text contains the term
if (original.indexOf(term) > -1) {
return data;
}
// If it doesn't contain the term, don't return anything
return null;
}
Actually found the solution by modifying the matcher opt
$("#myselect").select2({
matcher: function(term, text, opt){
return text.toUpperCase().indexOf(term.toUpperCase())>=0 || opt.parent("optgroup").attr("label").toUpperCase().indexOf(term.toUpperCase())>=0
}
});
Under the premise that the label attribute has been set in each optgroup.
Found a solution from select2/issues/3034
Tested with select2 v.4
$("select").select2({
matcher(params, data) {
const originalMatcher = $.fn.select2.defaults.defaults.matcher;
const result = originalMatcher(params, data);
if (
result &&
data.children &&
result.children &&
data.children.length
) {
if (
data.children.length !== result.children.length &&
data.text.toLowerCase().includes(params.term.toLowerCase())
) {
result.children = data.children;
}
return result;
}
return null;
},
});
A few minor changes to people suggested code, less repetitive and copes when there are no parent optgroups:
$('select').select2({
matcher: function(term, text, opt){
var matcher = opt.parent('select').select2.defaults.matcher;
return matcher(term, text) || (opt.parent('optgroup').length && matcher(term, opt.parent('optgroup').attr("label")));
}
});
I am having issues with my application. I have a db table for a print queue. When I read from that table in a loop, once I add that record to the view model, I then want to delete it from the database...this would be the most efficient way to do it, but EF barks:
An entity object cannot be referenced by multiple instances of IEntityChangeTracker.
I've tried using multiple contexts... but that didn't seem to work either. I've seen articles like Rick Strahl's, but frankly it was above my level of understanding, and not exactly sure if it helps my issue here and seemed quite an in depth solution for something as simple as this.
Is there a simple way to accomplish what I am trying to achieve here?
Here is my code:
public List<InventoryContainerLabelViewModel> CreateLabelsViewModel(int intFacilityId)
{
var printqRep = new Repository<InventoryContainerPrintQueue>(new InventoryMgmtContext());
var printqRepDelete = new Repository<InventoryContainerPrintQueue>(new InventoryMgmtContext());
IQueryable<InventoryContainerPrintQueue> labels =
printqRep.SearchFor(x => x.FacilityId == intFacilityId);
List<InventoryContainerLabelViewModel> labelsViewModel = new List<InventoryContainerLabelViewModel>();
if (labels.Count() > 0)
{
//Get printq record
foreach (InventoryContainerPrintQueue label in labels)
{
IEnumerable<InventoryContainerDetail> icDtls =
label.InventoryContainerHeader.InventoryContainerDetails;
//Get print details
foreach (InventoryContainerDetail icDtl in icDtls)
{
labelsViewModel.Add(new InventoryContainerLabelViewModel()
{
...
populate view model here
}
);//Add label to view model
} //for each IC detail
//Delete the printq record
printqRepDelete.Delete(label); <======== Error Here
} //foreach label loop
}//label count > 0
return labelsViewModel.ToList();
}
In the end, I added a column to the printq table for status, then in the the loop updated it to processed, then called a separate method to delete it.
public List<InventoryContainerLabelViewModel> CreateLabelsViewModel(int intFacilityId)
{
InventoryMgmtContext dbContext = new InventoryMgmtContext();
var printqRep = new Repository<InventoryContainerPrintQueue>(dbContext);
IEnumerable<InventoryContainerPrintQueue> unprintedPrtqRecs =
printqRep.SearchFor(x => x.FacilityId == intFacilityId && x.Printed == false);
List<InventoryContainerLabelViewModel> labelsViewModel = new List<InventoryContainerLabelViewModel>();
if (unprintedPrtqRecs.Count() > 0)
{
//Get printq record
foreach (InventoryContainerPrintQueue unprintedPrtqRec in unprintedPrtqRecs)
{
IEnumerable<InventoryContainerDetail> icDtls =
unprintedPrtqRec.InventoryContainerHeader.InventoryContainerDetails;
//Get container details to print
foreach (InventoryContainerDetail icDtl in icDtls)
{
labelsViewModel.Add(new InventoryContainerLabelViewModel()
{
...
}
);//Get IC details and create view model
} //for each IC detail
unprintedPrtqRec.Printed = true;
printqRep.Update(unprintedPrtqRec, unprintedPrtqRec, false);
} //foreach label loop
//Commit updated to Printed status to db
dbContext.SaveChanges();
}//label count > 0
return labelsViewModel;
}
public ActionConfirmation<int> DeletePrintQRecs(int intFacilityId)
{
InventoryMgmtContext dbContext = new InventoryMgmtContext();
var printqRep = new Repository<InventoryContainerPrintQueue>(dbContext);
IEnumerable<InventoryContainerPrintQueue> printedPrtqRecs =
printqRep.SearchFor(x => x.FacilityId == intFacilityId && x.Printed == true);
foreach (InventoryContainerPrintQueue printedPrtqRec in printedPrtqRecs)
{
//Delete the printq record
printqRep.Delete(printedPrtqRec, false);
}
//Save Changes on all deletes
ActionConfirmation<int> result;
try
{
dbContext.SaveChanges();
result = ActionConfirmation<int>.CreateSuccessConfirmation(
"All Label Print Q records deleted successfully.",
1);
}
catch (Exception ex)
{
result = ActionConfirmation<int>.CreateFailureConfirmation(
string.Format("An error occured attempting to {0}. The error was: {2}.",
"delete Label Print Q records",
ex.Message),
1
);
}
return result;
}