python - MongoEngine returns empty list -

i have database named suvaider. contains 2 collection relation , reviews. have filled these 2 importing json files. have created models these 2 collections. while trying use these models data mongoengine returns empty array. i'm beginner i'm using mongodb first time flask. in advance!!!

# models.py      flask import url_for     suvaiderbackend import db      class hotels(db.embeddeddocument):         property_id = db.stringfield(max_length=255,required=true)         name = db.stringfield(max_length=255,required=true)      class relation(db.document):         parent = db.embeddeddocumentfield('hotels')         units = db.listfield(db.embeddeddocumentfield('hotels'))      class reviews(db.document):         property_id = db.stringfield(max_length=255,required=true)         rating = db.intfield(default=0)         review = db.stringfield()         sentiment = db.stringfield(max_length=255)         review_link = db.stringfield()   #this __init__.py         flask import flask          flask.ext.mongoengine import mongoengine         app = flask(__name__)         app.config["mongodb_settings"] = {'db': "suvaider"}         app.config["secret_key"] = "keep3h9secret"          db = mongoengine(app)          if __name__ == '__main__':              app.run(debug=true) 

according documentation mongoengine default converts document class name lowercase , use name of collection. in example looks collections named: relation , reviews. since have existing database different collections(notice spelling - first letter uppercase) should set custom collection name adding

meta = {'collection': 'collectionname'} 

to documents.

class relation(db.document):     parent = db.embeddeddocumentfield('hotels')     units = db.listfield(db.embeddeddocumentfield('hotels'))     meta = {'collection': 'relation'}  class reviews(db.document):     property_id = db.stringfield(max_length=255,required=true)     rating = db.intfield(default=0)     review = db.stringfield()     sentiment = db.stringfield(max_length=255)     review_link = db.stringfield()     meta = {'collection': 'reviews'}