FIX: Sort separator '.' was breaking deep fields, '~' instead

[mcd-php]

'~' is 1) Not reserved by http://tools.ietf.org/html/rfc3986 2) Does not mix with namespace/class/name separator in any major programming language

[coveralls]

Coverage decreased (-0.49%) when pulling 411ad98 on mcd-php:fix-sort-separators into 016d796 on yiisoft:master.

[klimov-paul]

Using “~” symbol in URLs is not recommended, because different URL encode standards processes it in different way:
See http://www.faqs.org/rfcs/rfc1738
See http://www.faqs.org/rfcs/rfc3986

[mcd-php]

So what instead ? Underscore ? Is popular in field names in snake case. Sub-delims from rfc3986, and tolerate % ?
Use '->' for deep sorting as i do now and '.' for relations, and keep converting both ways ?

[cebe]

what is the problem with .?

[mcd-php]

Problem is what i have deep sorting ( by related fields, #1185) and now implementing it into the database layer (CassandraMemSortDataProvider). In DB layer . is used to separate deep nested relations (with(['obPerson.arCertificate'])) and . does not get through Sort object.

Currently i use -> as deep sort delimiter, but two-way conversion will add space for error.

[qiangxue]

How about we use comma , to separate different attributes and : to separate sort direction from attribute name? Yes, both characters are reserved ones, but it seems they are commonly used.

[mcd-php]

@qiangxue Symbol choice completely up to the team, I ultimately resign in the area of RFC and web practice intricacies.

BTW, do you need the deep ArrayHelper::getValue() ?

[cebe]

How about we use comma , to separate different attributes and : to separate sort direction from attribute name? Yes, both characters are reserved ones, but it seems they are commonly used.

fine with me.