Row Selection is not consistent when we navigate between pages.

[pandey-mohit]

This link is present in your officical site under "Server-Side Paging Example"
http://plnkr.co/edit/50vJrs?p=preview

Steps to reporduce:

1. Select number of rows in 1st page, let say, you selected 2 rows. Then, "Selected Items" counts will show "2".
2. Now move to 2nd page and do not perform any action.
3. Now come back(navigate) to 1st page again.
4. Here, no row is selected but "Selected Items" counts still show "2". Moreover, if we select more rows, it will start incrementing the count from "2" to "3". And on unselecting, count will go back to "2" (but not to zero, in any case).

[c0bra]

@pandey-mohit This is ng-grid (v2.x) and will be superseded by UI-Grid (3.x) in the near future.

Here's a quick plunker showing selection + pagination in 3.x: http://plnkr.co/edit/qoEQd6F6qHvGwrrUrIzp?p=preview

[pandey-mohit]

@c0bra : I already implemented ng-grid in our current project and its harder to switch to ui-grid.

Is there any quick-fix for it?

[c0bra]

@pandey-mohit There may be a fix, but I'm not aware of one; sorry! I was never involved in the 2.x pagination stuff.

[tzweiner]

@c0bra: can you show an example with server-side pagination? I'm experiencing the exact same issue on ui.grid 3.0.0 rc20.

Your plunker is using standard pagination, and it works just fine. However, I'm using external pagination and I'm seeing the exact behavior that pandey-mohit described above.

[pandey-mohit]

@tzweiner : I solve the above issue by adding "primaryKey" property to gridOptions. You need to pass a unique field to it.

Example:
Let say, you have a data
[{
id: 1,
name: "tzweiner"
}, {
id: 2,
name: "pandey-mohit"
}, {
id: 3,
name: "cObra"
}]

In it, "id" is your unique field, you can assign it as a primary key "primaryKey: 'id'". It will solve the above mentioned issue (in my case, it works like a charm).

Also, "primaryKey" field is never mentioned in ng-grid documentation but i read about it in another open issue raised for row selection problem.

[tzweiner]

Yes, I did read about primaryKey and included it. This is what I've included in my gridOptions:
primaryKey: 'documentId',
columnDefs: [
{field: 'ti', displayName: 'Pub. Title'},
{field: 'pt', displayName: 'Journal Title'},
{field: 'vol', displayName: 'Pub. Volume'},
{field: 'iss', displayName: 'Pub. Issue'},
{field: 'documentId', displayName: 'Doc ID'}],

I still get the unwanted behavior of Selected Items remembering an obsolete count after paging (via external pagination).

[pandey-mohit]

Please create an example (http://jsfiddle.net/) for it.

[tzweiner]

I tried Plnkr but as soon as I add in ui-grid it blanks out.

[tzweiner]

@pandey-mohit I forked @c0bra 's plnkr which uses ui-grid and take a look here
http://plnkr.co/edit/UBrmbISCSaYIkFG173lX?p=preview

Select some rows on page 1, then go to next page, come back to page 1. Nothing there is selected but Selected Items keeps showing the old count and when you select more rows, the count is incremented in a way that does not correspond to the number of selected rows.

This uses primaryKey.

[tzweiner]

This is essentially happening because with External Pagination we are loading new data every time. So we lose track of any row properties (such as "selected") when we load in the new page data. We probably need to maintain a record of what's been selected separately in a service or something and then select manually any rows that were previously selected.

I still think that there's something wonky about Selected Items tho. It should show 0 after you load another set of rows, or remember internally which rows were previously selected when you come back to a page with already selected rows.

[PaulL1]

Expected behaviour for ui-grid based on looking at the code is that:

1. With internal pagination we have access to the full set of rows, we're just showing a page at a time using a rowProcessor. So if you select a row then change pages then that row is still selected, when you go back to the page the row should still be selected (it just wasn't visible for a while, similar to having filtered it)
2. With external pagination we can no longer see the row - you're removing it from the data. So when you change page we lose sight of the row, and lose it's selected status. If you want to retain the selection status you'd need to do "getSelectedRows" before changing page, save it somewhere (perhaps in an array of selection states, one per page), and then apply it again when the user comes back to that same page. You could perhaps use saveState for this if you wanted, but it's probably not overly complex to code it directly.

[tzweiner]

Yes, that was the conclusion I arrived at too. I ended up saving any checked off rows in a service and then selecting them back manually once we bring them back into the result set.

I had to remove this tho: 'showGridFooter: true' because it was causing Selected Items in the footer to show the wrong count. I implemented my own counter for that as well.