I follow this instruction to create a #userAware annotation which automatically limits all queries on specific entities to the current user.
For example $todoRepo->findByTag("someTag") will automatically add WHERE user_id = 123 to the resulting query to make sure that only ToDo entities of the current user (id 123) can be accessed.
This works great but has one big downside: If for example the admin whats to know how many ToDo entities use the tag someTag he will only find his own entities...
Since using an #userAware annotation seems to be quite common, I wonder if there is any best practice on how to disable/bypass/override this filter/annotation on a specific query.
You can disable the filter. In your example, you must change the kernel request event, like that ...
public function onKernelRequest()
{
if ($user = $this->getUser()) {
if ($user->isAdmin() /* or whatever */) {
$this->em->getFilters()->disable('user_filter');
} else {
$filter = $this->em->getFilters()->enable('user_filter');
$filter->setParameter('id', $user->getId());
$filter->setAnnotationReader($this->reader);
}
}
}
I want to return a $firebaseArray of records that contain a particular value without knowing the parent ID.
So in this case, I want to get all the objects under 'challenges' that contain the ID pictured above starting with LNF.
I have tried using orderByChild and equalTo, but again this seems to requiring knowing the parent ID. Is there a way around this?
If you want everything with key CPjip3tVE1Q067Qzx6p0vij0k1|1try this:
var key = "CPjip3tVE1Q067Qzx6p0vij0k1|1";
for child in snapshot.children {
if child.key == key {
get your data
}
}
You can use that to loop over all of the children under "challenges"
I am using kentico application where i have to delete all child items which contains either node id of parent or parentnodeid of parent based on the child inside there.
Below is the screen shot:
In this picture we can see we have a parent node called membership and inside one child called Blog. Under of Blog which node id is 583 having 29 child. Now I am running a code and getting all the child data under of that parent as a list.
Below is the screen shot:
Now i have to remove all the child data from list whose parentnodeid or parent-parent node id is 583 (Blog).
Below is the code used to get the list of all parent and child items:
TreeProvider tree = new TreeProvider();
var childNodeDataSet = tree.SelectNodes(childNodeId, null, SiteContext.CurrentSiteName);
var getAllChildItems = childNodeDataSet.Items[0].AllChildren;
var getItems = getAllChildItems.ToList().OrderBy(a=>a.NodeAliasPath);
As we can see above code childNodeId is nothing but the Membership page node id. Using this i am getting all the child items.
Now in this getItems i have all the values where i have to remove Blog page parent and child completely.
I tried this code to remove the matching parent item from list:
string excludeFileName = "583, 683, 686, 687";
string[] arrStringList = excludeFileName.Split(',');
foreach (var excName in arrStringList)
{
getItems.RemoveAll(a => (a.NodeID == Convert.ToInt32(excName.Trim()) || a.NodeParentID == Convert.ToInt32(excName.Trim()))
|| (a.Parent.NodeID == Convert.ToInt32(excName.Trim()) || a.Parent.NodeParentID == Convert.ToInt32(excName.Trim()))
|| (a.Parent.Parent.NodeID == Convert.ToInt32(excName.Trim()) || a.Parent.Parent.NodeParentID == Convert.ToInt32(excName.Trim()))
|| (a.Parent.Parent.Parent.NodeID == Convert.ToInt32(excName.Trim()) || a.Parent.Parent.Parent.NodeParentID == Convert.ToInt32(excName.Trim())));
}
This code is working fine if i know particular node has how many level.
But if some of the node don't have that much level then in that case this code is giving exception.
If found any issues please let me know.
I am a little confused at the path you're taking. If you want to get all children of a particular node, why not just get all nodes where the NodeAliasPath is like "The/Parent/Node/Path"+"/%"?
This will select all the children nodes all the way down.
If you only want to grab a certain number of levels, you can get the Parent's NodeLevel, and then in the query add a NodeLevel <= "+(ParentNodeLevel+2) to grab all the children and grandchildren only.
To exclude certain nodes, you can also put a "NodeID not in (123,234)".
Perhaps if you can clearly say what you are trying to accomplish we can help out easier!
PS: I Put the SQL, but the DocumentQuery object has most of these in methods, like .WhereNotIn("NodeID", ListOfNodeIDsToExclude)
I'm trying to test out Firebase to allow users to post comments using push. I want to display the data I retrieve with the following;
fbl.child('sell').limit(20).on("value", function(fbdata) {
// handle data display here
}
The problem is the data is returned in order of oldest to newest - I want it in reversed order. Can Firebase do this?
Since this answer was written, Firebase has added a feature that allows ordering by any child or by value. So there are now four ways to order data: by key, by value, by priority, or by the value of any named child. See this blog post that introduces the new ordering capabilities.
The basic approaches remain the same though:
1. Add a child property with the inverted timestamp and then order on that.
2. Read the children in ascending order and then invert them on the client.
Firebase supports retrieving child nodes of a collection in two ways:
by name
by priority
What you're getting now is by name, which happens to be chronological. That's no coincidence btw: when you push an item into a collection, the name is generated to ensure the children are ordered in this way. To quote the Firebase documentation for push:
The unique name generated by push() is prefixed with a client-generated timestamp so that the resulting list will be chronologically-sorted.
The Firebase guide on ordered data has this to say on the topic:
How Data is Ordered
By default, children at a Firebase node are sorted lexicographically by name. Using push() can generate child names that naturally sort chronologically, but many applications require their data to be sorted in other ways. Firebase lets developers specify the ordering of items in a list by specifying a custom priority for each item.
The simplest way to get the behavior you want is to also specify an always-decreasing priority when you add the item:
var ref = new Firebase('https://your.firebaseio.com/sell');
var item = ref.push();
item.setWithPriority(yourObject, 0 - Date.now());
Update
You'll also have to retrieve the children differently:
fbl.child('sell').startAt().limitToLast(20).on('child_added', function(fbdata) {
console.log(fbdata.exportVal());
})
In my test using on('child_added' ensures that the last few children added are returned in reverse chronological order. Using on('value' on the other hand, returns them in the order of their name.
Be sure to read the section "Reading ordered data", which explains the usage of the child_* events to retrieve (ordered) children.
A bin to demonstrate this: http://jsbin.com/nonawe/3/watch?js,console
Since firebase 2.0.x you can use limitLast() to achieve that:
fbl.child('sell').orderByValue().limitLast(20).on("value", function(fbdataSnapshot) {
// fbdataSnapshot is returned in the ascending order
// you will still need to order these 20 items in
// in a descending order
}
Here's a link to the announcement: More querying capabilities in Firebase
To augment Frank's answer, it's also possible to grab the most recent records--even if you haven't bothered to order them using priorities--by simply using endAt().limit(x) like this demo:
var fb = new Firebase(URL);
// listen for all changes and update
fb.endAt().limit(100).on('value', update);
// print the output of our array
function update(snap) {
var list = [];
snap.forEach(function(ss) {
var data = ss.val();
data['.priority'] = ss.getPriority();
data['.name'] = ss.name();
list.unshift(data);
});
// print/process the results...
}
Note that this is quite performant even up to perhaps a thousand records (assuming the payloads are small). For more robust usages, Frank's answer is authoritative and much more scalable.
This brute force can also be optimized to work with bigger data or more records by doing things like monitoring child_added/child_removed/child_moved events in lieu of value, and using a debounce to apply DOM updates in bulk instead of individually.
DOM updates, naturally, are a stinker regardless of the approach, once you get into the hundreds of elements, so the debounce approach (or a React.js solution, which is essentially an uber debounce) is a great tool to have.
There is really no way but seems we have the recyclerview we can have this
query=mCommentsReference.orderByChild("date_added");
query.keepSynced(true);
// Initialize Views
mRecyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
mManager = new LinearLayoutManager(getContext());
// mManager.setReverseLayout(false);
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(mManager);
I have a date variable (long) and wanted to keep the newest items on top of the list. So what I did was:
Add a new long field 'dateInverse'
Add a new method called 'getDateInverse', which just returns: Long.MAX_VALUE - date;
Create my query with: .orderByChild("dateInverse")
Presto! :p
You are searching limitTolast(Int x) .This will give you the last "x" higher elements of your database (they are in ascending order) but they are the "x" higher elements
if you got in your database {10,300,150,240,2,24,220}
this method:
myFirebaseRef.orderByChild("highScore").limitToLast(4)
will retrive you : {150,220,240,300}
In Android there is a way to actually reverse the data in an Arraylist of objects through the Adapter. In my case I could not use the LayoutManager to reverse the results in descending order since I was using a horizontal Recyclerview to display the data. Setting the following parameters to the recyclerview messed up my UI experience:
llManager.setReverseLayout(true);
llManager.setStackFromEnd(true);
The only working way I found around this was through the BindViewHolder method of the RecyclerView adapter:
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
final SuperPost superPost = superList.get(getItemCount() - position - 1);
}
Hope this answer will help all the devs out there who are struggling with this issue in Firebase.
Firebase: How to display a thread of items in reverse order with a limit for each request and an indicator for a "load more" button.
This will get the last 10 items of the list
FBRef.child("childName")
.limitToLast(loadMoreLimit) // loadMoreLimit = 10 for example
This will get the last 10 items. Grab the id of the last record in the list and save for the load more functionality. Next, convert the collection of objects into and an array and do a list.reverse().
LOAD MORE Functionality: The next call will do two things, it will get the next sequence of list items based on the reference id from the first request and give you an indicator if you need to display the "load more" button.
this.FBRef
.child("childName")
.endAt(null, lastThreadId) // Get this from the previous step
.limitToLast(loadMoreLimit+2)
You will need to strip the first and last item of this object collection. The first item is the reference to get this list. The last item is an indicator for the show more button.
I have a bunch of other logic that will keep everything clean. You will need to add this code only for the load more functionality.
list = snapObjectAsArray; // The list is an array from snapObject
lastItemId = key; // get the first key of the list
if (list.length < loadMoreLimit+1) {
lastItemId = false;
}
if (list.length > loadMoreLimit+1) {
list.pop();
}
if (list.length > loadMoreLimit) {
list.shift();
}
// Return the list.reverse() and lastItemId
// If lastItemId is an ID, it will be used for the next reference and a flag to show the "load more" button.
}
I'm using ReactFire for easy Firebase integration.
Basically, it helps me storing the datas into the component state, as an array. Then, all I have to use is the reverse() function (read more)
Here is how I achieve this :
import React, { Component, PropTypes } from 'react';
import ReactMixin from 'react-mixin';
import ReactFireMixin from 'reactfire';
import Firebase from '../../../utils/firebaseUtils'; // Firebase.initializeApp(config);
#ReactMixin.decorate(ReactFireMixin)
export default class Add extends Component {
constructor(args) {
super(args);
this.state = {
articles: []
};
}
componentWillMount() {
let ref = Firebase.database().ref('articles').orderByChild('insertDate').limitToLast(10);
this.bindAsArray(ref, 'articles'); // bind retrieved data to this.state.articles
}
render() {
return (
<div>
{
this.state.articles.reverse().map(function(article) {
return <div>{article.title}</div>
})
}
</div>
);
}
}
There is a better way. You should order by negative server timestamp. How to get negative server timestamp even offline? There is an hidden field which helps. Related snippet from documentation:
var offsetRef = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com/.info/serverTimeOffset");
offsetRef.on("value", function(snap) {
var offset = snap.val();
var estimatedServerTimeMs = new Date().getTime() + offset;
});
To add to Dave Vávra's answer, I use a negative timestamp as my sort_key like so
Setting
const timestamp = new Date().getTime();
const data = {
name: 'John Doe',
city: 'New York',
sort_key: timestamp * -1 // Gets the negative value of the timestamp
}
Getting
const ref = firebase.database().ref('business-images').child(id);
const query = ref.orderByChild('sort_key');
return $firebaseArray(query); // AngularFire function
This fetches all objects from newest to oldest. You can also $indexOn the sortKey to make it run even faster
I had this problem too, I found a very simple solution to this that doesn't involved manipulating the data in anyway. If you are rending the result to the DOM, in a list of some sort. You can use flexbox and setup a class to reverse the elements in their container.
.reverse {
display: flex;
flex-direction: column-reverse;
}
myarray.reverse(); or this.myitems = items.map(item => item).reverse();
I did this by prepend.
query.orderByChild('sell').limitToLast(4).on("value", function(snapshot){
snapshot.forEach(function (childSnapshot) {
// PREPEND
});
});
Someone has pointed out that there are 2 ways to do this:
Manipulate the data client-side
Make a query that will order the data
The easiest way that I have found to do this is to use option 1, but through a LinkedList. I just append each of the objects to the front of the stack. It is flexible enough to still allow the list to be used in a ListView or RecyclerView. This way even though they come in order oldest to newest, you can still view, or retrieve, newest to oldest.
You can add a column named orderColumn where you save time as
Long refrenceTime = "large future time";
Long currentTime = "currentTime";
Long order = refrenceTime - currentTime;
now save Long order in column named orderColumn and when you retrieve data
as orderBy(orderColumn) you will get what you need.
just use reverse() on the array , suppose if you are storing the values to an array items[] then do a this.items.reverse()
ref.subscribe(snapshots => {
this.loading.dismiss();
this.items = [];
snapshots.forEach(snapshot => {
this.items.push(snapshot);
});
**this.items.reverse();**
},
For me it was limitToLast that worked. I also found out that limitLast is NOT a function:)
const query = messagesRef.orderBy('createdAt', 'asc').limitToLast(25);
The above is what worked for me.
PRINT in reverse order
Let's think outside the box... If your information will be printed directly into user's screen (without any content that needs to be modified in a consecutive order, like a sum or something), simply print from bottom to top.
So, instead of inserting each new block of content to the end of the print space (A += B), add that block to the beginning (A = B+A).
If you'll include the elements as a consecutive ordered list, the DOM can put the numbers for you if you insert each element as a List Item (<li>) inside an Ordered Lists (<ol>).
This way you save space from your database, avoiding unnecesary reversed data.
I want to implement some search condition like the below which I want to make in best optimized way, how can I achieve this?
switch (e.CommandName)
{
case "DRESS":
chkItem.Items.Clear();
chkItem.DataSource = cDressing.GetAllDressingDetail(cWebUtil.CurrClientID);
chkItem.DataTextField = "Description";
chkItem.DataValueField = "DressingID";
chkItem.DataBind();
CurrBtnMode = btnMode.Dressing;
// ModalPopupExtender1.TargetControlID = ((Button)grdOrder.Rows[currItem.OrderItemID -1].FindControl("btnDress")).ID.ToString();
if (currItem.DressingItems.Count > 0)
{
foreach(cOrderItemDressing itemDress in currItem.DressingItems )
{
// I want here to apply condtion for those chkItem object's DressingID exist in the itemDress objets's DressingID should
// have checked state in checkbox list to be populated.
}
}
ModalPopupExtender1.Show();
Is you goal to check the items in the chkItem.Items that have a matching item in the currItem.DressingItems collection? I'm not sure if this is what you want to get, but you can try this:
...
//uncheck all the items first (if you need it)
foreach (var item in chkItem.Items)
{
item.Checked = false;
}
foreach(cOrderItemDressing itemDress in currItem.DressingItems )
{
bool chkItemFound = false;
foreach (var item in chkItem.Items)
{
//if the item is found, make it checked
if (item.DressingID == itemDress.DressingID)
{
item.Checked = true;
chkItemFound = true;
break;
}
}
}
I haven't tested this yet, so if you've got some issues when using it, just let me know.
Update
You asked if it's the most optimized way of solving the issue. I would say there are more optimized methods, but I wanted to keep the code simple to just show the solution.
It may be sufficient, but it depends on how many items does each of the collections contain.
I suppose that a quite simple way to optimize it would be preventing so many items comparisons by removing an item you've already found (because it's not needed in further comparisons). This way the collection can shrink with each loop iteration, making it work faster. You may need, however, to create a copy of the collection you want to modify in order to have acces to its original form (and keep note that allocation of this array can take some time).
Another way would be using sorted collections and implementing some kind of searching algorithm for them. This will make the searching process itself faster, but needs some additional time to sort the collections (sorting can also be implemented by creating collection in a sorted form, so no sorting is needed later).
There are probably some other ways to do it, but it can depend on the details of other parts of your application and amount of data you want it to work with.