MongoRepository Find List in Array

Question

I've got a document that looks like this

@Document
public @Data class Note {

    @Id
    private String noteId;
    private String owner;
    @TextIndexed
    private String name;
    @TextIndexed
    private String text;
    private List<String> tags;
    private LocalDate date;
}

Also I'm using spring data mongodb to operate on mongodb datastore. I've created interface

public interface NoteRepository extends MongoRepository<Note, String> {
    List<Note> findByTags(List<String> tags);
}

My stored object looks like this

[
    {
        "noteId": "594e4adc3bc5152218f933b4",
        "owner": "system",
        "name": "simple note",
        "text": "My text",
        "tags": [
            "tag1",
            "tag2",
            "tag3"
        ],
        "date": [
            1992,
            12,
            15
        ]
    }
]

But unless I don't provide the list of tags like tag1, tag2, tag3 to findByTags method it won't return any result. For example tag1, tag2 returns nothing etc. etc.

How should I conduct the search over such tags? Use some TextCriteria?

Answer 1

It depends on what you want to provide.

If you just want a single value then MongoDB does not care if the data is in an array and will simply look for the match in all entries

public interface NoteRepository extends MongoRepository<Note, String> {
    List<Note> findByTags(String tags);
}

If you want a list of variable size for comparison of "any" that may match, then there is a keyword used by spring-mongo that effects the $in operation:

public interface NoteRepository extends MongoRepository<Note, String> {
    List<Note> findByTagsIn(List<String> tags);
}

So the first is for where you just want "tag1" to match the data. And the second would match a List like "tag1", "tag2", or anything as long as 'at least one' was actually present in the array being searched.