Redux-Firestore bug #45 | Work Around? - javascript

I am running into this bug where if I delete a document from firestore my redux store shows it as null appose to removing it from the store. If I check firestore, I do indeed see it is deleted.
This causes my front-end to break because my .map functions are unable to map null arguments. If could run conditional statements to see if an item in the array is null, then remove this from the array but I wanted to see if there was a more elegant way to handle this bug until it is resolved?
I am using the firetore.data store.
Bug details here
delete does not remove item from data state # 45
https://github.com/prescottprue/redux-firestore/issues/45

I opted to create my own workaround until this bug is resolved.
Create a if statement to check to see if your state has the data. convert this data to an Array and then filter out any undefined data to create your final array.
// Check to see if data exist
if (this.props.userData) {
// Convert data to array
let data = Object.values(this.props.userData);
// Filters undefined objects due to react-redux-firestore bug
data = data.filter(singleData => {
return singleClass !== undefined;
});
}

Related

How to prevent the sequelize from creating the output clause

When I do a create using sequelize it returns me the response i.e. the newly created entry row in the response,
Sequelize Create Object Code:
let createdObj= await sequelize.ModelName.create(modelObject,{ transaction :t, //more options can be added here, need some value of option that prevents the output inserted })
Below is the query created:
INSERT INTO [TABLE_NAME] ([COL1],[COL2],[COL3],[COL4]) OUTPUT INSERTED.* VALUES (#0,#1,#2,#3,#4)
Now I don't want the output clause to be part of the query, I want a simple insert like:
INSERT INTO [TABLE_NAME] ([COL1],[COL2],[COL3],[COL4]) VALUES (#0,#1,#2,#3,#4)
I don't want the output clause to be part of the query.
How can I achieve this in at the query level as well as at the model level? In some Create operations, I want the output clause and in some create operations, I don't want.
EDIT 1
On Further research I found an option called { returning: false } this does what is required i.e. create an insert query like this INSERT INTO [TABLE_NAME] ([COL1],[COL2],[COL3],[COL4]) VALUES (#0,#1,#2,#3,#4) but now the Sequelize is breaking because it's expecting those values back in return idk why?
C:\Users\MG265X1\project\node_modules\sequelize\lib\dialects\mssql\query.js:389
id = id || results && results[0][this.getInsertIdField()];
^
TypeError: Cannot read property 'id' of undefined
at Query.handleInsertQuery (C:\Users\MG265X1\project\node_modules\sequelize\lib\dialects\mssql\query.js:389:39)
Turns out if an autoIncrementAttribute is present in the model, it will look for the output clause, removing the attribute {autoIncrement: true } from the model hasn't helped as IDENTITY_INSERT cannot be null. How do I move ahead on this??
Edit 2 I could get it working with a combination of { returning: false } and {hasTriggers: true}. Have hasTriggers Attribute as true in your Model, this will allow you to single creates but for bulk Creates pass option returning: false at the time of bulkCreate.
Note: When using bulkCreate with { returning: false } you'll not be able to get the autogenerated Id, It's a trade-off that we had to live with as we want
bulkCreate to work with triggers, we ended up fetching the Id later from DB
Seems I raised this issue but was closed as it wasn't good SSCCE

Implementing Keras Model into website with Keras.js

I have been trying to implement a basic Keras model generated in Python into a website using the Keras.js library. Now, I have the model trained and exported into the model.json, model_weights.buf, and model_metadata.json files. Now, I essentially copied and pasted test code from the github page to see if the model would load in browser, but unfortunately I am getting errors. Here is the test code. (EDIT: I fixed some errors, see below for remaining ones.)
var model = new KerasJS.Model({
filepaths: {
model: 'dist/model.json',
weights: 'dist/model_weights.buf',
metadata: 'dist/model_metadata.json'
},
gpu: true
});
model.ready()
.then(function() {
console.log("1");
// input data object keyed by names of the input layers
// or `input` for Sequential models
// values are the flattened Float32Array data
// (input tensor shapes are specified in the model config)
var inputData = {
'input_1': new Float32Array(data)
};
console.log("2 " + inputData);
// make predictions
return model.predict(inputData);
})
.then(function(outputData) {
// outputData is an object keyed by names of the output layers
// or `output` for Sequential models
// e.g.,
// outputData['fc1000']
console.log("3 " + outputData);
})
.catch(function(err) {
console.log(err);
// handle error
});
EDIT: So I changed my program around a little to be compatible with JS 5 (that was a stupid mistake on my part), and now I have encountered a different error. This error is caught and then is logged. The error I get is: Error: predict() must take an object where the keys are the named inputs of the model: input. I believe this problem arises because my data variable is not in the correct format. I thought that if my model took in a 28x28 array of numbers, then data should also be a 28x28 array so that it could correctly "predict" the right output. However, I believe I am missing something and that is why the error is being thrown. This question is very similar to mine, however it is in python and not JS. Again, any help would be appreciated.
Ok, so I figured out why this was happening. There were two problems. First, the data array needs to be flattened, so i wrote a quick function to take the 2D input and "flatten" it to be a 1D array of length 784. Then, because I used a Sequential model, the key name of the data should not have been 'input_1', but rather just 'input'. This got rid of all the errors.
Now, to get the output information, we simply can store it in an array like this: var out = outputData['output']. Because I used the MNIST data set, out was a 1D array of length 10 that contained probabilities of each digit being the user-written digit. From there, you can simply find the number with the highest probability and use that as a prediciton for the model.

ES6 class getter, temporary return or alternative solution

I am trying to solve a problem I am seeing when rendering a list of items in my ui that is coming out of a es6 class I have created. The model is working great, however I am using animations that are listening to (in react) mount, onEnter, and onLeave of the items.
When I apply my filters and sorting via the model and spit back the new list of items via the getter, the animations do not apply to some items because the list is just being re sorted, not necessarily changed.
So my getter just grabs this.products of the class and returns it and applies a sort order to it. And if filters are applied (which are tracked by this._checkedList in the class), the this.products is reduced based on which filters are selected then sorted. So that getter looks like so :
get productList() {
if (this._checkedList.length > 0) {
const filteredProducts = _.reduce(this.filterMap, reduceFilters, []);
const deDuped = _.uniq(filteredProducts, 'id');
return this.applySort(deDuped);
}
const deDuped = _.uniq(this.products, 'id');
return this.applySort(deDuped);
}
What I am trying to figure out, is a way to to temporarily send back an empty array while the filters or sorting run. The reason being the ui would receive an empty array (even if for a split second) and react would register the new sorted/filtered list as a new list and fire the enter/leave/mount animations again.
My attempt was to set a local property of the class like -
this._tempReturn = false;
then in the functions where the sort or filter happen, I set it to true, then back to false when the function is done like this -
toggleFilter(args) {
this._tempReturn = true;
...toggle logic
this._tempReturn = false;
}
Then changed the getter to check for that property before i do anything else, and if it's true, send back an empty array -
get productList() {
if (this._tempReturn) {
return [];
}
...
}
However, this does not seem to work. Even putting a console.log in the if (this._tempReturn) { didn't show any logs.
I also tried sending back a new list with lodash's _.cloneDeep like so :
get productList() {
if (this._checkedList.length > 0) {
const filteredProducts = _.reduce(this.filterMap, reduceFilters, []);
const deDuped = _.uniq(filteredProducts, 'id');
return _.cloneDeep(this.applySort(deDuped));
}
const deDuped = _.uniq(this.products, 'id');
return _.cloneDeep(this.applySort(deDuped));
}
this did not work either. So it seems the empty array return might be a better approach.
I am wondering if there is some way to achieve this - I would like to have the array be return empty for a second perhaps while the filters and sort are applying.
Very stuck on how to achieve, perhaps I am even looking at this problem from the wrong angle and there is a much better way to solve this. Any advice would be welcomed, thanks for reading!
In order to force a re-render of items in a list when updating them you just need to make sure that each items has a unique key property.
Instead of rendering the list, then rendering it as empty, then re-rendering a changed list make sure each child has a unique key. Changing the key property on a child in an array will always cause it to re-render.

Display posts in descending posted order

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.

Checking for equivelance

OK, I'm missing something here and I just can't seem to find it because the logic seems correct to me, but I'm certain I'm not seeing the error.
var VisibleMarkers = function() {
var filtered = _.reject(Gmaps.map.markers, function(marker) {
return marker.grade != $('.mapDataGrade').val() && !_.contains(marker.subjects,$('.mapDataSubjects').val())
});
return filtered
}
I'm using underscore.js and jQuery to simplify my javascript work.
So right now, I'm checking by means of selects which data gets to be rejected and then I display the filtered markers on the (google) map (if it helps at all, this is using gmaps4rails which is working perfectly fine, its this bit of javascript that's making me lose the last of the hairs on my head).
Currently, the code functions 100% correctly for the ".mapDataGrade" select, but the ".mapDataSubjects" isn't. Now the markers object has a json array of the subjects (this is for students) and each item in the array has its ID. Its this ID that I am supposed to be checking.
Can someone see what I'm doing wrong?
If there's more info that needs to be included, please let me know.
This is on plain javascript on a RoR application using gmaps4rails
Now the markers object has a json array of the subjects (this is for students) and each item in the array has its ID. Its this ID that I am supposed to be checking.
_.contains compares a values, but it sounds like you want your iterator to compare a value to an object's "id" property. For that, _.some would work; it's like contains, except that, instead of comparing values, you can write the comparison as a function:
Returns true if any of the values in the list pass the iterator truth test.
Here's how you'd use it:
!_.some(marker.subjects, function(subject) {
return subject.id == $('.mapDataSubjects').val();
})
If I'm right, the whole line should be like this:
return marker.grade != $('.mapDataGrade').val() &&
// check that none of the subjects is a match
!_.some(marker.subjects, function(subject) {
// the current subject is a match if its ID matches the selected value
return subject.id == $('.mapDataSubjects').val();
});

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