Added sortOrder option (deprecating sortDirection on columns object)

[patorjk]

In the current API, the table's sort direction is held in one of the column options objects. This has the following problems:

• It leads to ambiguity if multiple columns have this field set.
• It's makes it hard to implement multiple level sorting (where a table is first sorted by 1 column, and then for values that are the same a second column is used to sort). You can see an example of this in jQuery Datatables - click a column header, and then shift+click another header. The second column is used to break ties.
• It adds unnecessary complexity to users who use the serverSide option, since a sort value is typically passed to the server separately, and in the current implementation it burred in one of the column's options.

This PR removes sortDirection from the column's object, and creates a "sortOrder" property on the options, examplet:

var options = {
    sortOrder: {
        name: ${selectedColumn},
        direction: ${direction}
    }
};

I may change columnName to "name" and sortDirection to "direction".

[coveralls]

Coverage increased (+0.6%) to 75.972% when pulling 2f087d2 on v3_sortOrder into b8eec4c on v3.

[wdh2100]

it seems to be a very good change.

sortDirection	string		Set default sort order enum('asc', 'desc', 'none') (null option has been deprecated, use 'none' instead)
that's confusing in my opinion

I may change columnName to "name" and sortDirection to "direction".

var options = {
    sortDirection: {
        name: ${selectedColumn},
        direction: ${direction}
    }
};

me, too 👍

serverSide should change the option, right?

Oh 😃 . already applied to the sample.

https://github.com/gregnb/mui-datatables/pull/1310/files#diff-f7e1f12cc2cd7d7d0b7e0aba3823d92bR88-R91

but I think we should consider backward compatibility.

https://github.com/gregnb/mui-datatables/pull/1310/files#diff-4f4aff53b74d2c551e37786d32b82e3aR486

Is this enough?

[patorjk]

@wdh2100 I think you're right, backward compatibility for something like this is a good idea. I've updated the PR to account for "sortDirection" if no sortOrder value is present. I also updated the field names.

[mxmlnglt]

@patorjk you said earlier "It's makes it hard to implement multiple level sorting": can you confirm this is not yet implemented?

[patorjk]

Correct, it's not yet implemented.

[broncha]

Didn't this disable sort by multiple columns? Now you can only sort by one column