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React table pre select rows

I'm trying to preselect rows in my table but the table won't refresh unless there are changes to the actual data itself. Is there a method to reinit the table that doesn't involve changing the data?
It's also completely possible that my method for approaching this requirement is wrong and there may be a better way? I've created an example sandbox here:
https://codesandbox.io/s/mock-preselected-rows-data-t36nl?file=/src/App.js
In this you can see I have a mock response from my server for determining what rows should be selected. I'm then grabbing the data to compare to see if any of the items from the mock response exist in the data and if so push them to a new obj which is then fed into the intialState for selectedRowIds
Any guidance appreciated.

Seems your work is all working. The short answer to your question.
As long as you want the user see something, in a React way, it needs to be contained in a state, or state derivative. In your case, it's a cell data wrapped in row and in a table.
So you can't avoid selecting it without touching the data. Unless you don't want user see the change.
Although the checkbox doesn't seem to be part of the original data stream, when you develop on it, you have to make it part of the data. To be honest, it's easy you make it part of the data, because by the time you want to refresh the table, ex. selecting or de-selecting, or deleting a row, you want everything refreshed. Unfortunately it's very difficult to do local refresh with a table in React. It's possible, but very difficult, because most of the design is based on either prop or context.

You can also refactor your handleSelectedRows function.
// Find row ids and compare them with our 'preSelectedTheseItems' array.
const handleSelectedRows = () => {
const preIds = preSelectTheseItems.map(item => item.collectibleId)
return data?.filter((collectibleRow, index) => preIds.includes(collectibleRow.collectibleId));
};
Example : codesandbox

Tabulator.js table elements retrieve the index of the row and serve as a control element to other plots

I am using tabulator package 4.3.0 to work on a webpage. The table generated by the package is going to be the control element of a few other plots. In order to achieve this, I have been adding a dataFiltered function when defining the table variable. But instead of getting the order of the rows in my data object, I want to figure a way to get the index of the rows in the filtered table.
Currently, I searched the manual a little bit and have written the code analogue to this:
dataFiltered: function(filters,rows){
console.log(rows[0]._row.data)
console.log(rows[0].getPosition(true));
}
But the getPosition always returned -1, which refers to that the row is not found in the filtered table. I also generated a demo to show the real situ when running the function. with this link: https://jsfiddle.net/Binny92/3kbn8zet/53/.
I would really appreciate it if someone could help me explain a little bit of how could I get the real index of the row in the filtered data so that I could update the plot accordingly and why I am always getting -1 when running the code written in this way.
In addition, I wonder whether there is a way to retrieve the data also when the user is sorting the table. It's a pity that code using the following strategy is not working in the way I am expecting since it is not reacting to the sort action and will not show the information when loading the page for the first time.
$('#trialTable').on('change',function(x){console.log("Yes")})
Thank you for your help in advance.

The reason this is happening is because the dataFiltered callback is triggered after the rows are filtered but before they have been laid out on the table, so they wont necessarily be ready by the time you call the getPosition function on them.
You might do better to use the renderComplete callback, which will also handle the scenario when the table is sorted, which would change the row positions.
You could then use the getRows function passing in the value "active" as the first augment return only rows that have passed the filter:
renderComplete: function(){
var rows = table.getRows("active");
console.log(rows[0].getPosition(true));
}
On a side note i notice you are trying to access the _row property to access the row data. By convention underscore properties are considered private in JavaScript and should not be accessed as it can result in unstable system behaviour.
Tabulator has an extensive set of functions on the Row Component to allow you to access anything you need. In the case of accessing a rows data, there is the getData function
var data = row.getData();

Putting Firestore data into array with Angular

I have created a small application for keeping track of how much time I spend in different courses (as a teacher) using Angular 5 and putting my data in Firestore via AngularFire2. Most things have worked out nicely, but for the final part of the application I am having serious problems. I am quite a newbie at Angular/Firebase and most importantly (perhaps) with reactive programming.
The data that is stored in Firestore is quite simple:
Data stored in Firebase It consists of six fields for information about the course, when the course was held and most importantly what I did (called Element) and for how long (called Duration).
Now, what I would like to do is to make a report that summaries all the durations for each thing I did (Element). In essence, what I would like to do is the equivalent of a GroupBy in SQL. As I understand it Firebase does not have an operation for grouping.
My, so far failed approach to this, has been to try to create an array into which I put the data and make calculations on that. It is here that I fail.
My first attempt is based on creating an observer as most examples for retrieving data in tutorials use. WorkItem is a simple class that has the same content as in Firebase.
this.lectureDoc = this.afs.collection(`users/${this.afAuth.auth.currentUser.uid}/regTime`,
ref => ref.where('course', '==', this.selectedCourse.courseName).orderBy('element') );
this.lectureItems = this.lectureDoc.snapshotChanges().pipe(
map (courses => courses.map(a => {
const data = a.payload.doc.data() as WorkItem;
const id = a.payload.doc.id;
return { id, ...data };
})
));
this.lectureItems.subscribe(item => {
item.forEach(i => {
this.allElements.push(i);
});
});
console.error(this.allElements);
console.error(this.allElements[0]);
The two last lines show the problem, namely that the first (of the two last lines) will return the complete array while the second will return 'undefined'.
I understand that reactive programming will make asynchronous calls and that I therefore cannot know for sure when the data is filled. However, I do not understand why I can see the content of the array in the first of the two last lines, but not in the second.
My second attempt is based on getting the data from the documents of the collection itself and also, to prevent empty arrays, using .then() but again the two last lines show exactly the same output as previously.
this.lectureDoc.ref.get().then(item => {
item.forEach(i => {
this.lectures.push(i.data() as WorkItem);
});
});
console.error(this.lectures);
console.error(this.lectures[0]);
The output can be seen in this image: Output from the running program
So, to recap, what I would like to do is to collect all the data in an array of WorkItem and then calculate how much time has been spent on different tasks and then display it in list on the web page. I have not come to the display part and I suspect that I will have trouble again with the array not being populated when bound to the list. I have a hard time to understand reactive programming...
Any help would be greatly appreciated!
//Tobias

This is a pretty common behaviour of the console as far as I'm aware, at least in Chrome. When you log data that's async but haven't been populated yet, the console will still show the array once the async operation is completed.
But when you log an object in the array, at the time that you log it that object isn't there yet, therefore the log will show as undefined.
Simply do the logging inside of the forEach and you will see the data being pushed properly.
An another case, example there: Console.log behavior

Parse.com relations count

I want to query object from Parse DB through javascript, that has only 1 of some specific relation object. How can this criteria be achieved?
So I tried something like this, the equalTo() acts as a "contains" and it's not what I'm looking for, my code so far, which doesn't work:
var query = new Parse.Query("Item");
query.equalTo("relatedItems", someItem);
query.lessThan("relatedItems", 2);

It seems Parse do not provide a easy way to do this.
Without any other fields, if you know all the items then you could do the following:
var innerQuery = new Parse.Query('Item');
innerQuery.containedIn('relatedItems', [all items except someItem]);
var query = new Parse.Query('Item');
query.equalTo('relatedItems', someItem);
query.doesNotMatchKeyInQuery('objectId', 'objectId', innerQuery);
...
Otherwise, you might need to get all records and do filtering.
Update
Because of the data type relation, there are no ways to include the relation content into the results, you need to do another query to get the relation content.
The workaround might add a itemCount column and keep it updated whenever the item relation is modified and do:
query.equalTo('relatedItems', someItem);
query.equalTo('itemCount', 1);

There are a couple of ways you could do this.
I'm working on a project now where I have cells composed of users.
I currently have an afterSave trigger that does this:
const count = await cell.relation("members").query().count();
cell.put("memberCount",count);
This works pretty well.
There are other ways that I've considered in theory, but I've not used
them yet.
The right way would be to hack the ability to use select with dot
notation to grab a virtual field called relatedItems.length in the
query, but that would probably only work for me because I use PostGres
... mongo seems to be extremely limited in its ability to do this sort
of thing, which is why I would never make a database out of blobs of
json in the first place.
You could do a similar thing with an afterFind trigger. I'm experimenting with that now. I'm not sure if it will confuse
parse to get an attribute back which does not exist in its schema, but
I'll find out, by the end of today. I have found that if I jam an artificial attribute into the objects in the trigger, they are returned
along with the other data. What I'm not sure about is whether Parse will decide that the object is dirty, or, worse, decide that I'm creating a new attribute and store it to the database ... which could be filtered out with a beforeSave trigger, but not until after the data had all been sent to the cloud.
There is also a place where i had to do several queries from several
tables, and would have ended up with a lot of redundant data. So I wrote a cloud function which did the queries, and then returned a couple of lists of objects, and a few lists of objectId strings which
served as indexes. This worked pretty well for me. And tracking the
last load time and sending it back when I needed up update my data allowed me to limit myself to objects which had changed since my last query.

KnockoutJS: Update/Insert data to a viewModel using mapping

I've been trying to figure this out for quite some time now. I couldn't find anything that addresses this problem, but please correct me if I'm wrong.
The problem:
I have data from a JSON API comming in, with an nested array/object structure. I use mapping to initially fill the model with my data. To update this, I want to extend the model if new data arrives, or update the existing data.
As far as I found out, the mapping option key, should do this trick for me, but I might have misunderstood the functionality of the mapping options.
I've boiled down the problem to be represented by this example:
var userMapping = {
key: function(item) {
return ko.utils.unwrapObservable(item.id);
}
};
// JSON call replaced with values
var viewModel = {
users: ko.mapping.fromJS([], userMapping)
};
// Should insert new - new ID?
ko.mapping.fromJS([{"id":1,"name":"Foo"}, {"id":2,"name":"Bar"}], userMapping, viewModel.users);
// Should only update ID#1 - same ID?
ko.mapping.fromJS([{"id":1,"name":"Bat"}], userMapping, viewModel.users);
// Should insert new - New ID?
ko.mapping.fromJS([{"id":3,"name":"New"}, {"id":4,"name":"New"}], userMapping, viewModel.users);
ko.applyBindings(viewModel);​
Fiddle: http://jsfiddle.net/mikaelbr/gDjA7/
As you can see, the first line inserts the data. All good. But when I try to update, it replaces the content. The same for the third mapping; it replaces the content, instead of extening it.
Am I using it wrong? Should I try to extend the content "manually" before using mapping?
Edit Solution:
I solved this case by having a second helper array storing all current models. On new data i extended this array, and updated the view model to contain the accumulated items.
On update (In my case a WebSocket message), I looped through the models, changed the contents of the item in question, and used method valueHasMutated() to give notice of changed value to the Knockout lib.

From looking at your example code the mapping plugin is behaving exactly as I would expect it to. When you call fromJS on a collection you are effectively telling the mapping plugin this is the new contents of that collection. For example:
On the second line, How could it know whether you were updating or whether you had simply removed id:2?
I can't find any mention of a suitable method that treats the data as simply an update, although you could add one. Mapped arrays come with some helpful methods such as mappedIndexOf to help you find particular items. If you receive an update data set simply loop through it, find the item and update it with a mapping.fromJS call to that particular item. This can easily be generalized into reusable method.

You can use ko.mapping.updateFromJS() to update existing values. However, it does not add new values so that would be a problem in your instance. Take a look at the link below for more details.
Using updateFromJS is replacing values when it should be adding them

Yes, you should first collect all data into a list or array and then apply the mapping to that list. Otherwise you are going to overwrite the values in your viewModel.