Support for compareFunction for sorted method

[andrei-tofan]

In the latest version of RealmSwift is possible to provide a compare function to the sorted method, this is very useful for more complex sorting and locale-aware sorting (sorting edge case - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/localeCompare#using_options).

Is there a way to supply a compare function to the sorted method? Didn't find an option in the documentation.

[kneth]

@andrei-tofan The short answer is no.

The reason why we haven't added the functionality so far is that we fear that the many callbacks to JavaScript will degenerate the performance to an unacceptable level.

[jaltin]

Hi @kneth. Your point about performance concerns is understandable.

Is there another way this could be solved? For example by passing a sort priority string into realm when opening the DB (or at any point that is more suitable), so you could do the sorting natively for performance reasons? This would make it super flexible for us as developers to control the sorting and be sure it behaves the same as in JS.

For example, a sort string could look like this for swedish:

'­� _-,;:!¡?¿.·'"«»()[]{}§¶@*/&#%`´^¯¨¸°©®+±÷×<=>¬|¦~¤¢$£¥01¹½¼2²3³¾456789aAbBcCçÇdDðÐeEéÉèÈêÊëËfFgGhHiIíÍìÌîÎïÏjJkKlLmMnNñÑoOºóÓòÒôÔöÖõÕøØpPqQrRsSßtTuUúÚùÙûÛüÜvVwWxXyYýÝÿzZþÞµªáÁàÀâÂåÅäÄãÃæÆ',

and like this for english

'� _-,;:!?.'"()[]{}@*/&#%`^+<=>|~$0123456789aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ',

[jaltin]

Hi again @kneth. What do you think about my suggestion from 7 days ago? Thx!

[kneth]

@jaltin

A generic solution for sorting isn't trivial to implement as outlined in realm/realm-core#2573. In particular, Android doesn't have support for ICU.

Realm Core doesn't provide a callback mechanism, but it might be worth considering instead of keep waiting for Android NDK to provide the optimal solution.

[jaltin]

Hi @kneth,

Pinging this issue to see if you have the possibility to look into this further?

Thx!

[kneth]

@jaltin We haven't priorities it before but I will bring it up after the holidays.