Allow computed fields based on database fields (HIDE in compiler)

A way I have found that works pretty well with sqldelight is to have two different models separated, one for the database model and another for the data that comes from network. Thus sqldelight forces you to some types based on the database logic (that can be different to the presentation logic) with autovalue it gets a bit messy to mix Database, network and presentation in the same model.

Said that, now when we have a factory, this factory needs a generic class that extends your SomethingModel, but what if I want to have a FACTORY object that provides me the mapping between the presentation and the database without creating a new instance of the database object, that will avoid huge memory allocations with big lists.

Let me show an example. I have two classes: Comment and CommentDb. Comment is my presentation which can have an id null and CommentDb is my database layer.

Comment.java

@AutoValue
public abstract class Comment {

    @Nullable
    public abstract Long id();

    @NonNull
    public abstract Long postId();

    @NonNull
    public abstract String name();

    @NonNull
    public abstract String email();

    @NonNull
    public abstract String body();

    @NonNull
    public abstract Long createdAt();

    @Nullable
    public abstract Long updatedAt();

    @Nullable
    public abstract Long deletedAt();

    public abstract boolean needsSync();

    @NonNull
    public ContentValues marshal(){
        return CommentDb.FACTORY.marshal()
                ._id(id())
                ._postId(postId())
                ._name(name())
                ._body(body())
                ._email(email())
                ._createdAt(createdAt())
                ._updatedAt(updatedAt())
                ._deletedAt(deletedAt())
                ._needsSync(needsSync())
                .asContentValues();
    }

    @NonNull
    public static Builder builder() {
        return new AutoValue_Comment.Builder();
    }

    @NonNull
    public static Builder builder(@NonNull Comment comment) {
        return builder()
                .postId(comment.postId())
                .id(comment.id())
                .name(comment.name())
                .email(comment.email())
                .body(comment.body())
                .createdAt(comment.createdAt())
                .updatedAt(comment.updatedAt())
                .deletedAt(comment.deletedAt())
                .needsSync(comment.needsSync());
    }

    @AutoValue.Builder
    public static abstract class Builder {

        @NonNull
        public abstract Builder id(@Nullable Long id);

        @NonNull
        public abstract Builder postId(@NonNull Long postId);

        @NonNull
        public abstract Builder name(@NonNull String name);

        @NonNull
        public abstract Builder email(@NonNull String email);

        @NonNull
        public abstract Builder body(@NonNull String body);

        @NonNull
        public abstract Builder createdAt(@NonNull Long createdAt);

        @NonNull
        public abstract Builder updatedAt(@Nullable Long updatedAt);

        @NonNull
        public abstract Builder deletedAt(@Nullable Long deletedAt);

        @NonNull
        public abstract Builder needsSync(@Nullable boolean needsSync);

        @NonNull
        public abstract Comment build();
    }
}

CommentDb.java

@AutoValue
public abstract class CommentDb implements CommentModel {

    public static final Factory<CommentDb> FACTORY = new Factory<>(new CommentModel.Creator<CommentDb>() {
        @Override
        public CommentDb create(long id, long postId, String name, String body, String email, long createdAt, Long updatedAt, Long deletedAt, boolean needsSync) {
            return new AutoValue_CommentDb(id, postId, name, body, email, createdAt, updatedAt, deletedAt, needsSync);
        }
    });

    public static final RowMapper<CommentDb> COMMENTS_POST_MAPPER = FACTORY.selectCommentsPostMapper();

    public static final RowMapper<CommentDb> SYNC_POSTS_MAPPER = FACTORY.selectSyncCommentsMapper();
}

Said that, I would like to be able to do something like:

public static final Factory<Comment> FACTORY = new Factory<>(new CommentModel.Creator<Comment>() {
        @Override
        public Comment create(long id, long postId, String name, String body, String email, long createdAt, Long updatedAt, Long deletedAt, boolean needsSync) {
            //build here my comment based on the database info
        }
    });

[droidpl]

Ok, then just a good documentation for it will be needed and a detailed explanation for what you can use it. 👍 Go for the HIDE

[droidpl]

hey @AlecStrong! I had to re-read the whole issue since I completely forgot what was it about 😄 Yeah I can understand the timings, it is indeed a major change. Sounds good to me, this way the mapping will be way more flexible and also computing fields can be done in an easier way than including more syntax to the database creation.

Thanks for the good work