没有公开的RealmResults <E> 构造函数？

Question

I've got a table that has Realm Objects I'm calling Foo . One of the columns of Foo points to another Realm Object , Bar . I want to query table Foo and pick out all of the Bar objects I need, and then add them to a RealmBaseAdapter .

However, to my knowledge, RealmBaseAdapter only takes a RealmResults list in it's constructor. How would I form a RealmResults of Bar without querying the Bar table? Or, how would I query the Foo table and get back a RealmResults of Bar ?

For example, say you had a table of product's and product segments, eg rice krispies, corn flakes, fruit loops would all belong to the cereal product segment. I wish to query a table of products by some specification, and list all of the product segments that are contained in the result.

Answer 1

Since there was no way to do this directly, I ended up making my own adapter.

 public class BarAdapter extends ArrayAdapter<Bar>  {

      //code to instantiate the adapter, inflate views, etc

 }

This part was trivial, the only hard work to be done was by curating a query from Foo-->Bar that would get me the results that I wanted. It ended up looking something like this,

    // where fooType was what I wanted to ween out the Foo results on before
    // selecting Bar objects.
    RealmQuery<Foo> fooRealmQuery = realm
            .where(Foo.class)
            .equalTo("fooType", "desired type")
            .or()
            .equalTo("fooType", "other type");
    RealmResults<Foo> fooList = fooRealmQuery.findAll();

    List<Bar> barList = new ArrayList<Bar>();
    for (Foo foo : fooList) {

        Bar bar = foo.getBar();

        if (!barList.contains(bar)) {
            barList.add(bar);
            Log.d(TAG, "added " + bar.getName());
        } else {
            Log.d(TAG, "I already had that bar");
        }
    }

    adapter = new BarAdapter(this, barList);
    listView.setAdapter(adapter);

Now things work well. Also, Realm is fast enough that I can query right as I'm creating the adapter and I see no performance lag :)

Answer 2

What you are asking is currently not possible using the current RealmBaseAdapter , at least not if you want to display Bar objects from a Foo query.

If you don't want to maintain a relationship from Bar to Foo, I would recommend creating your RealmAdapter instead where able to filter your Foo query for the Bar objects you wanted to display. The RealmBaseAdapter contains very little code, so it should be fairly easy to customize: RealmBaseAdapter.java