I want to return a List of "Posts" from an endpoint with optional pagination. I need 100 results per query. The Code i have written is as follows, it doesn't seem to work. I am referring to an example at Objectify Wiki
Another option i know of is using query.offset(100);
But i read somewhere that this just loads the entire table and then ignores the first 100 entries which is not optimal.
I guess this must be a common use case and an optimal solution will be available.
public CollectionResponse<Post> getPosts(@Nullable @Named("cursor") String cursor,User auth) throws OAuthRequestException {
if (auth!=null){
Query<Post> query = ofy().load().type(Post.class).filter("isReviewed", true).order("-timeStamp").limit(100);
if (cursor!=null){
query.startAt(Cursor.fromWebSafeString(cursor));
log.info("Cursor received :" + Cursor.fromWebSafeString(cursor));
} else {
log.info("Cursor received : null");
}
QueryResultIterator<Post> iterator = query.iterator();
for (int i = 1 ; i <=100 ; i++){
if (iterator.hasNext()) iterator.next();
else break;
}
log.info("Cursor generated :" + iterator.getCursor());
return CollectionResponse.<Post>builder().setItems(query.list()).setNextPageToken(iterator.getCursor().toWebSafeString()).build();
} else throw new OAuthRequestException("Login please.");
}
This is a code using Offsets which seems to work fine.
@ApiMethod(
name = "getPosts",
httpMethod = ApiMethod.HttpMethod.GET
)
public CollectionResponse<Post> getPosts(@Nullable @Named("offset") Integer offset,User auth) throws OAuthRequestException {
if (auth!=null){
if (offset==null) offset = 0;
Query<Post> query = ofy().load().type(Post.class).filter("isReviewed", true).order("-timeStamp").offset(offset).limit(LIMIT);
log.info("Offset received :" + offset);
log.info("Offset generated :" + (LIMIT+offset));
return CollectionResponse.<Post>builder().setItems(query.list()).setNextPageToken(String.valueOf(LIMIT + offset)).build();
} else throw new OAuthRequestException("Login please.");
}
