0 evaluates to false in a logical context, allow a zero to be returned for totalRows

[camallen]

avoid 0 being treated as false in the || statement.

[Mottie]

The way the code is set up now:

result = c.ajaxProcessing(data, table) || [ 0, [] ],
// allow [ total, rows, headers ]  or [ rows, total, headers ]
t = isNaN(result[0]) && !isNaN(result[1]);
// ...
c.totalRows = result[t ? 1 : 0] || c.totalRows || 0;

if no result is returned from ajax, or the result is zero, it will then return the current c.totalRows, and if that is zero, it will then return zero. Is this a problem with the c.totalRows not being zero?

Maybe I'm not seeing how the above is different from this:

rr_count = result[t ? 1 : 0];
c.totalRows = isNaN(rr_count) ? c.totalRows || 0 : rr_count;

rr_count should always return a number (or maybe undefined) since it is coming from the server. If it isn't then the server side code should be modified?

[camallen]

@Mottie, perhaps i should have set up some context for my pull request.

Let's say i am using server side filtering and the ajax pager with 100 records on the server. On initial load of the table i get 10 records for the first page, 1-10 / 100 and c.totalRows = 100.

Lets say that i then run some restrictive filtering that returns no rows but the total rows are the same (ajaxProcessing result = [ 100, [ [] ] ]). The table will have no rows but the pager links will be active trying to page into nothing.

Now i want the pager links to be correct so i return 0 total rows (ajaxProcessing result = [ 0, [ [] ] ]) but total rows doesn't update as the code uses the existing count of c.totalRows.

Looking at the code:
t = isNaN(result[0]) && !isNaN(result[1]);
=> t = false

Before the pull request:
c.totalRows = result[t ? 1 : 0] || c.totalRows || 0;
=> 100
As the result[0] is 0, which when used in 0 || c.totalRows will return the c.totalRows value which is 100.

My pull request will not use the result[0] in a logical operation for detecting it's value:
rr_count = result[t ? 1 : 0];
=> 0
//check that the result is a number, if not use the previous c.totalRows || 0 //otherwise use the latest returned count. c.totalRows = isNaN(rr_count) ? c.totalRows || 0 : rr_count;
=> 0

I think my use case is not the most common as most users won't have a changing totalRows count on the pager. However this change should be backwards compatible with any previous use cases and my filtering use case.

I hope i've explained the reasoning for the pull request.

Cheers,
Cam

[sbine]

@camallen Thank you, I was looking for a solution to this issue.

[camallen]

Hey @sbine, glad I could help.

Hopefully @Mottie accepts this pull request when he gets back from his sabbatical.