Pagination intermittently doesn't work

[francisbyrne]

I've noticed that the pagination for Collections-based datatables just doesn't work sometimes. It seems to happen when you navigate away from a page with a datatable on it (via iron-router) then navigate back to the original page and use the pagination.

To Reproduce:

1. Clone https://github.com/francisbyrne/finance
2. mrt install; meteor
3. Go to localhost:3000 in browser
4. Sign up a new account
5. Open console and enter loadDummyImports() (that will load a bunch of trades to populate the table)
6. Test the pagination; it should work
7. Navigate to "Trades" then back to "Portfolio"
8. Test the pagination; this time it doesn't work

I'll try and reproduce it with a simpler example but here are some screenshots from my finance project in the meantime.

[serenitus]

Hi Francis,

It's possible, looking at your code, that you've hit the same problem I hope I've just solved. You have structured things the same way I had, by implementing the DataTables configuration as a template helper. After going through a whole evening's worth of trial and error contrasting what I had against the example, I put the config in the data property of the IronRouter controller thus:

SearchController = RouteController.extend({
    template: 'noticesSearch',
    data: function () {
        'use strict';

        return {
            rows: {
                columns: [{
                    title: 'Date',
                    data: 'noticedate',
                    mRender: function (data, type, row) {
                        return moment(row.noticedate).format('DD/MM/YYYY');
                    }
                }, {
                    title: 'Died on',
                    data: 'diedon',
                    mRender: function (data, type, row) {
                        return moment(row.diedon).format('DD/MM/YYYY');
                    }
                }, {
                    title: 'Family name',
                    data: 'familyname'
                }, {
                    title: 'First names',
                    data: 'firstnames'
                }, {
                    title: 'Estate value',
                    data: 'estatevalue',
                    mRender: function (data, type, row) {
                        return accounting.formatMoney(row.estatevalue, '£ ', 0);;
                    }
                }],
                subscription: 'all_notices',
                options: {
                    order: [0, 'asc']
                }
            }
        };
    }
});

While this has fixed the problem I'd be interested to hear Austin's thoughts. Especially as the README.md shows exactly the "broken" technique.

Hope this helps!

[therealyoram]

I encountered the same problem today, and after spending hours and hours… i've found a solution: change the "id" to an random value like Meteor.uuid().

pull request: https://github.com/francisbyrne/finance/pull/79

my bug reproduction process:

go to http://localhost:3000/
go to http://localhost:3000/transactions
go to page 6
goto http://localhost:3000/
big bada boom: pagination is dead

[serenitus]

@joramhoefs that is one strange fix. It's quite hard to comprehend how that would make a difference as afaik that value is just used to provide a DOM element id to assist in applying CSS, etc. For this reason using a UUID is certainly counter to this purpose of this property!

[francisbyrne]

Thanks so much @joramhoefs!

It fixes my problem so I've merged the pull request but I think I'll leave this issue open for @austinrivas to respond to because it seems like a weird fix and maybe masking an underlying issue as @serenitus mentioned.

[therealyoram]

yes, it's not a clean solution. rather a dirty workaround with a slightly sarcastic note.
all hail our random non-identifying overlords! ;)
but it works with all the negative side effects. i'll deal with the real problem-as soon as i've time …

[serenitus]

I wonder if there's a problem whereby the rendering stage is finding that a DOM element with the specified id already exists. That would perhaps explain why your change works.

[francisbyrne]

@joramhoefs Weirdly enough, your fix with Meteor.uuid() actually breaks the reactive query I have with Session variables . See https://github.com/francisbyrne/finance/issues/81 for reproduction.

It appears we are opening a can of worms for this package! 😟

[francisbyrne]

Ah, I see what is happening. Every time it re-renders the table after the reactive query changes, it uses the original selector to get the table DOM but, since that has changed to a new uuid, it doesn't find anything.

Two solutions:

1. Change this.selector() to lookup the selector value at every time it runs, instead of storing a static data.selector value. Or,
2. Document that you can't use changing values (i.e. RNG values) as selectors, and fix the underlying pagination issue.

@austinrivas What do you think?

[serenitus]

@francisbyrne 1) sort of defeats the purpose of the id. You might as well just look up the class instead. Kills any potential for having multiple tables on the page also. 2) That would be the correct thing to do IMO.

There's 3) if you're using IronRouter, switch to the mechanism I described in my first response.

[chadrik]

Hey folks, @austinrivas has been sick the last week which is why it's been so quiet around here. He should be back to work sometime next week, I think. Just wanted to give you all a heads up.

[francisbyrne]

@chadrik thanks, good to know.
@serenitus Okay, I'm trying to switch to the Iron-Router solution you suggested but I keep getting errors. With your code block above, do you just call {{> DataTable}} in the template?

[serenitus]

@francisbyrne for me it looks like:

{{> DataTable columns=rows.columns subscription=rows.subscription options=rows.options }}

[francisbyrne]

@serenitus Hmmm, I can't seem to get it working with your approach.

Firstly, the reactive query doesn't work with this solution it seems; I just keep getting Exception from Deps recompute function: Error: Can't call non-function: undefined

Secondly, even if I ignore the query, I still get the same pagination issues as before.

So I'm just going to switch back to having it in the helper and see what @austinrivas comes back with regarding the pagination issues.