SpringData Page support

[b0c1]

Hi!

There is any way to get the Query object (before the run but after the fillQueryParameters) ? I want to call with Spring Data Pageable object to get paged result. Or JINQ have another way to create spring boot Page object? (It need the total number of result, not just the "page")

[my2iu]

Give me a few days to look over this Spring Data Pageable and see what's possible. While it is certainly possible to tweak JINQ so that you can get at the underlying Query object, you would then need to process the result set yourself, so things would start looking a little untidy. I'll try to see if something better can be done.

[my2iu]

It seems like the best choice might be to create a Jinq method for returning a Page from a Pageable. I'm still trying to figure out how it works. It seems like Spring simply issues two queries: one to get the total number of results and another to get the page data. It might take a while because I'll need to make a Spring project that actually uses Pageable so that I can do testing.

[my2iu]

Unfortunately, it looks like it'll take me a couple of days to figure out how to make a Spring project that uses pagination. I don't have those sorts of cycles available at the moment, so I'm going to have to defer this for a while. If you can find a sample project that uses the Pageable stuff (preferably, a variant of the Spring Petclinic), then I can probably work with that, but otherwise, I don't have the time at the moment to dig through the Spring documentation to see how to set up server-side pagination properly.

[b0c1]

Yeah, I found same things. Spring will use two query.
My solution:

protected <C, T> Page<C> asPaged(JPAJinqStream<T> source, Pageable pageable) {
        long total = source.count();
        if (pageable != null && pageable.getPageSize() > 0) {
            source = source.skip(pageable.getPageNumber() * pageable.getPageSize())
                    .limit(pageable.getPageSize());
        }
        List<C> result = source.toList();
        return new PageImpl<>(result, pageable, total);
}

[my2iu]

Great! Since you have a workaround, I won't prioritize making a solution to this issue. The solution I was thinking of is basically the same as what you have, but since it would take me a long to build the proper infrastructure to test it, it's probably not worth the trouble unless a lot of people need the same thing.

[b0c1]

Yeah but I have a problem with this... in spring the sorting is defined in the Pageable object... but it's string based... how can I convert it to CollectComparable ?

[my2iu]

I'm not sure. As I mentioned before, I'm having difficulty creating a simple Spring example that uses a Pageable that I can use to dig into the problem.

Presumably, you could just look at the string, and then manually write code to sort the results by the appropriate field. It's not a general mechanism, but if you're using Spring already, then you're probably having Spring autogenerate most of your queries and are only using Jinq for a couple of hard ones, in which case, you would only need to do it a few times.

I don't actually know what's in the string either. If you're willing to do the sort on the application server, then you could maybe use reflection to find a method/field that corresponds to the string and then sort the objects by that field. It's not clear where the string comes from either--does Spring verify that the String is valid, or can the user hack up different parameters to change it, leading to potential security problems?