Spring Data Rest - Sort by multiple properties

Question

I have an entity as below

Class Person{
String id;
String name;
String numberOfHands;
}

With Spring Data Rest (Gosling Release Train), I'm able to specify

localhost/Person?sort=name,asc

for sorting name name ascending. Now, in a case where I need to sort by numberOfHands descending and name ascending. I'm able to specify

localhost/Person?sort=numberOfHands,name,asc

But, I'm not able to specify

localhost/Person?sort=numberOfHands,desc,name,asc

Is there a way to specify multiple sort order?

Thanks!

Answer 1

Solution (tl;dr)

When wanting to sort on multiple fields you simply put the sort parameter multiple times in the URI. For example your/uri?sort=name,asc&sort=numberOfHands,desc. Spring Data is then capable of constructing a Pageable object with multiple sorts.

Explanation

There is not really a defined standard on how to submit multiple values for a parameter in a URI. See Correct way to pass multiple values for same parameter name in GET request.

However there is some information in the Java Servlet Spec which hints on how Java servlet containers parse request parameters.

The getParameterValues method returns an array of String objects containing all the parameter values associated with a parameter name. ... - Java Servlet Spec, section 3.1

The sample further in that section states (although it mixes request and body data)

For example, if a request is made with a query string of a=hello and a post body of a=goodbye&a=world, the resulting parameter set would be ordered a=hello, goodbye, world.

This sample shows that when a parameter (a in the example) is presented multiple times the results will be aggregated into a String[].

Answer 2

Here is how to construct the multi Sort object manually/programatically.

Sort sort = Sort.by(
    Sort.Order.asc("name"),
    Sort.Order.desc("numberOfHands"));
return personRepository.findAll(sort);

Note: This solution does not directly solve the original question asked, but may help visitors that landed on this question while searching for a solution how to sort on multiple properties from a backend perspective / in a somewhat "hardcoded" way. (this solution does not require/take any URI parameters)