Suppose I make a website that starts with initiating an instance of class 'Person' called 'person'.
Before saving 'person' to a database I want to manipulate some of the attributes using different html pages.
I don't understand how to keep track of the instance within Flask. How do I instruct Flask to keep track of the instance while moving from page to page?
See this simplified example within application.py:
from flask import ....
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
# database stuff deleted to keep it short
class Person(db.Model):
__tablename__ = "persons"
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Text)
nickname = db.Column(db.Text)
def __init__(self, name, nickname):
self.name = name
self.nickname = nickname
self.age
def set_age(self,age):
self.age = age
#app.route("/")
def index():
return render_template("index.html")
#app.route("/register", methods=["POST"])
def register():
if request.form["name"] == "" or request.form["nickname"] == "":
return render_template("failure.html")
person = Person(request.form["name"], request.form["nickname"])
db.session.add(person)
db.session.commit()
return render_template("add_age.html", person = person)
#app.route("/add_age")
def add_age():
age = 23
person.set_age = age
return redirect(url_for("index"))
So I want to edit the 'age' attribute from a different page in this example.
I really don't undestand your question but to do that you have to know how Flask's application context and request context work.
Check out http://flask.pocoo.org/docs/0.12/quickstart/#sessions to persist data on a browser's cookie and acces from all views
Related
I have User model and another model is user token
class User(EndpointsModel):
name = ndb.StringProperty()
#classmethod
def get_by_name(cls,name)
return cls.query(cls.name == name).get()
2 model is user token
class Token(EndpointsModel):
user = ndb.KeyProperty()
token = ndb.StringProperty()
#classmethod
def get_by_user(cls, key):
return cls.query(cls.token == key).get()
Now i fetch data from user
data = User.get_by_name('jaskaran')
when i try to fetch token then it return me None
print( Token.get_by_user(data.key) )
this is return None How can i fetch data from token with the help of user keyProrperty?
I think that you may be looking for ancestor queries, that according to the official documentation, look like this:
As the example in the docs shows:
purchases = Purchase.query(
Purchase.customer == customer_entity.key).fetch()
This applied to your use case will be then something like:
class Token(EndpointsModel):
user = ndb.KeyProperty(kind=User) #added kind User in key property, just in case
token = ndb.StringProperty()
#classmethod
def get_by_user(cls, key):
return cls.query(cls.token == key).fetch()
###Fetching data
data = User.get_by_name('jaskaran')
##HERE WILL BE GOOD TO PRINT DATA.KEY, FOR EXAMPLE,
##TO MAKE SURE THAT YOU ARE ACTUALLY RETRIEVING SOMETHING
print(data.key)
print(Token.get_by_user(data.key)
As a side note, the docs also explain that Account.get_by_id(...) is faster than Account.query(...).get(), therefore removing the .get() will be a good update to the code.
This question or many like it has been asked multiple times but for some reason I am unable to find the answer.
I do have this working to an extent in the way that if you go on the api pages, it renders, creates and updates without problem. The issue is displaying a field (title) from the nested object instead of just the primary key on the front end.
Some background before getting into the code:
Races is a finite list (e.g. Race1, Race2, Race3) and the front end does not have the ability to add more.
Cards is not finite, but each card must link to an existing Race (this currently does so by Primary Key).
The front end should display the card_text and race title of the linked race.
It also has the ability to add a new card but this works fine.
I have had this working with separate serializers for read and create/update where the read has a 'depth = 1' to pull through the entire object but the create/update doesn't and you then parse the object and send the primary key back (I couldn't find a way of doing this in the serializer, is it possible?).
So basically my question is, are you meant to pass the entire object through and parse it on a POST method, or do you pass the primary key and pull in the linked objects (Races) and use the primary key as an index (e.g. Races[card_race]). Also, why is 'linked_race' not coming through to the front end?
I realise I've almost answered my own question but as I'm new to Django I'm looking for the correct conventions and who knows, it may save someone else time when searching for the same answer.
urls.py
from .api import CardViewSet, RaceViewSet
from rest_framework.routers import DefaultRouter
from django.conf.urls import url, include
from .views import landing
router = DefaultRouter()
router.register(r'cards', CardViewSet)
router.register(r'races', RaceViewSet)
urlpatterns = [
url(r'^$', landing),
url(r'^api/', include(router.urls)),
]
api.py
from rest_framework.viewsets import ModelViewSet
from .serializers import CardSerializer, RaceSerializer
from .models import Card, Race
class CardViewSet(ModelViewSet):
queryset = Card.objects.filter(active=True)
def get_serializer_class(self):
return CardSerializer
def perform_create(self, serializer):
serializer.save(creator=self.request.user)
class RaceViewSet(ModelViewSet):
queryset = Race.objects.filter(active=True)
serializer_class = RaceSerializer
models.py
from django.db import models
from django.conf import settings
User = settings.AUTH_USER_MODEL
class Race(models.Model):
id = models.IntegerField(primary_key=True)
title = models.CharField(max_length=30, blank=False)
active = models.BooleanField(default=True)
def __str__(self):
return "{}".format(self.title)
def __unicode__(self):
return self.title
class Card(models.Model):
card_text = models.CharField(max_length=100, blank=False)
card_description = models.CharField(max_length=100, blank=True)
card_race = models.ForeignKey(Race, related_name='linked_race', on_delete=models.CASCADE)
creator = models.ForeignKey('auth.User', on_delete=models.CASCADE)
created = models.DateTimeField(auto_now_add=True)
active = models.BooleanField(default=True)
def __str__(self):
return self.card_text
class Meta:
ordering = ('created',)
serializers.py
from rest_framework import serializers
from .models import Card, Race
class RaceSerializer(serializers.ModelSerializer):
class Meta:
model = Race
fields = '__all__'
class CardSerializer(serializers.ModelSerializer):
linked_race = RaceSerializer(read_only=True, many=True)
class Meta:
model = Card
fields = 'id', 'card_text', 'card_description', 'card_race', 'linked_race',
Javascript extract (AngularJS)
$http.get('/api/races/').then(function (response) {
$scope.races = response.data;
$scope.selectedOption = $scope.races[0];
});
$scope.cards = [];
$http.get('/api/cards/').then(function (response) {
$scope.cards = orderBy(response.data, 'created', true);
});
html extract (AngularJS)
<div class="races--row" ng-repeat="c in cards | filter : card_filter |
orderBy : sortVal : sortDir" ng-class-odd="'odd'" ng-click="openModal(c)">
<div class="races--cell race">{{ c.card_race.title }}</div>
<div class="races--cell card-text">{{ c.card_text }}</div>
</div>
Your first "problem" is with the Card model (I say problem because I don't think you intended to do this). You're defining related_name='linked_race' for the card_race field. This related_name is the name you use to refer to a card FROM a race.
I would suggest you leave it out and use the default that Django already gives us (i.e. my_race.card_set.all() in this case). So change change that field in the Card model to:
class Card(models.Model):
...
card_race = models.ForeignKey(Race, on_delete=models.CASCADE)
...
And let's change the card serializer to:
class CardSerializer(serializers.ModelSerializer):
# no more linked_race
class Meta:
model = Card
fields = ('id', 'card_text', 'card_description', 'card_race')
Alright, this is a vary basic model serializer and you won't see details of a race yet. So now let's get to your main problem which was that you wanted to:
see the details of the associated race of a card
perform create/get/update/delete operations using the same serializer
For this, let's further change the CardSerializer to include another field called race_detail:
class CardSerializer(serializers.ModelSerializer):
race_detail = RaceSerializer(source='card_race', read_only=True)
class Meta:
model = Card
fields = ('id', 'card_text', 'card_description', 'card_race', 'race_detail')
We have defined two serializer fields for the same model field. Note the source and read_only attributes. This makes this field available when you GET a card (which is what we want), but not when you're performing POSTs or PUTs (which avoids the problem of sending the whole race object and parsing and stuff). You can just send the race id for the card_race field and it should work.
I am trying to create an app where I have Organizations and Roles, which have a many to many relationship, i.e the same role can exist in many organizations, and one organization can have many roles. To get entries, I want the user to fill up a form for an Organization, where he defines the name of the Organization and can then choose pre-existing roles, or add new ones.
How do I add new options for Role while defining an Organization if the ones already there are not enough?
I have the following models:
Class Organization(models.Model):
name = models.CharField(max_length=50)
roles = models.ManyToManyField('Role',blank=True)
owner_type = models.ForeignKey(ContentType)
owner_id = models.PositiveIntegerField()
owner = generic.GenericForeignKey('owner_type', 'owner_id')
Class Role(models.Model):
name = models.CharField(max_length=50)
These are the forms:
class OrganizationForm(forms.ModelForm):
class Meta :
model = Context
exclude = ('owner_type','owner_id','owner')
def __init__(self, user=None, *args, **kwargs):
self.user = user # get user here!
super(OrganizationForm, self).__init__(*args, **kwargs)
def save(self,commit = True):
new_org = super(OrganizationForm,self).save(commit=False)
new_org.owner = self.user
if commit:
new_org.save()
return new_org
This is the view I have so far,
def add_organization(request,template_name = "home/editorg.html"):
if request.POST:
form = OrganizationForm(request.user,request.POST)
if form.is_valid():
org = form.save(commit=False)
org.save()
form.save_m2m()
return HttpResponse('Entry made')
else:
form = OrganizationForm()
return render_to_response(template_name,{"form": form })
I am using Endpoints-proto-datastore written by Danny Hermes for Google App Engine and need help figuring out how to update an entity.. My model for what I need to update is the following
class Topic(EndpointsModel):
#_message_fields_schema = ('id','topic_name','topic_author')
topic_name = ndb.StringProperty(required=True)
topic_date = ndb.DateTimeProperty(auto_now_add=True)
topic_author = ndb.KeyProperty(required=True)
topic_num_views = ndb.IntegerProperty(default=0)
topic_num_replies = ndb.IntegerProperty(default=0)
topic_flagged = ndb.BooleanProperty(default=False)
topic_followers = ndb.KeyProperty(repeated=True)
topic_avg_rating = ndb.FloatProperty(default=0.0)
topic_total_rating = ndb.FloatProperty(default=0.0)
topic_num_ratings = ndb.IntegerProperty(default=0)
topic_raters = ndb.KeyProperty(repeated=True)
And as you can see, the rating properties have a default of 0. So each time a topic is rated, I need to update each of the rating properties. However, none of my properties is the actual rating being provided by the user. How can i pass in the value the user rated the topic to be able to update the properties in the model? Thanks!
You can do this by having an "alias" property called rating associated with your UserModel:
from endpoints_proto_datastore.ndb import EndpointsAliasProperty
class UserModel(EndpointsModel):
...
def rating_set(self, value):
# Do some validation
self._rating = value
#EndpointsAliasProperty(setter=rating_set)
def rating(self):
return self._rating
This will allow ratings to be sent with UserModels in requests but won't require those ratings to be stored.
You're better off using the OAuth 2.0 token for the user and calling endpoints.get_current_user() to determine who the user is in the request.
Something like a dedicated model for ratings could be much easier:
from endpoints_proto_datastore.ndb import EndpointsUserProperty
class Rating(EndpointsModel):
rater = EndpointsUserProperty(raise_unauthorized=True)
rating = ndb.IntegerProperty()
topic = ndb.KeyProperty(kind=Topic)
and then transactionally retrieving the Topic from the datastore and updating it in a request method decorated by #Rating.method.
I would like to create movies database, where user will be able to mark movies he/she watched and liked:
class Movies(ndb.Model):
watched = ndb.UserProperty()
liked = ndb.UserProperty()
Will that work? I use Google accounts.
How should I choose later all movies user liked?
Upd. I've followed systempuntoout approach and use the following code to save user choices:
user = users.get_current_user()
if user:
userschoices = models.UsersChoices(
movie=ndb.Key(models.Movies, movie_id), # TODO: what if movie_id is wrong?
watched=True,
user_id=user.user_id()
)
try:
userschoices.put()
self.response.out.write('1')
except:
self.response.out.write('0')
But if user makes his choice several times, then several records are added to the datastore...
Wouldn't be it better just to save user id and movie id as keyname?
userschoices = models.UsersChoices.get_by_id(user.user_id() + '-' + movie_id)
if userschoices is None:
userschoices = models.UsersChoices(id=user.user_id() + '-' + movie_id)
userschoices.movie = ndb.Key(models.Movies, movie_id) # TODO: what if movie_id is wrong?
userschoices.user_id = user.user_id()
if option == 'liked':
userschoices.liked = True
elif option == 'watched':
userschoices.watched = True
However, with such approach if I don't pass liked, then it overwrites its value with None (the same with watched, if not passed, None is used).
I would go with two different Models, one that stores all the Movies details and one to store the UserChoices :
class Movies(ndb.Model):
title = ndb.StringProperty(required=True)
director = ndb.StringProperty()
whatever = ndb.StringProperty()
class UsersChoices(ndb.Model):
movie = ndb.KeyProperty(kind=Movies, required=True)
watched = ndb.BooleanProperty(required=True)
liked = ndb.BooleanProperty(required=True)
user_id = ndb.StringProperty(required=True)
#classmethod
def get_liked_movies(cls, user_id):
return cls.query(cls.user_id == user_id, cls.liked == true).fetch(10)
#classmethod
def get_watched_movies(cls, user_id):
return cls.query(cls.user_id == user_id, cls.watched == true).fetch(10)
#classmethod
def get_by(cls, user_id, movie_key):
return cls.query(cls.user_id == user_id, cls.movie == movie_key).get()
If you need to store informations about users you should create your UserInfo Model, keyed by user_id from the users API, with all the details Properties your application needs.
class UserInfo(ndb.Model):
#Keyed by user_id
nickname = ndb.StringProperty()
email = ndb.StringProperty()
To create a new UserInfo, you could do:
from google.appengine.api import users
user = users.get_current_user()
userinfo = UserInfo(
id = user.user_id(),
nickname = user.keyname(),
email = user.email()
)
userinfo.put()
Then, when the user is logged in, use his/her user_id to retrieve the watched/liked movies.
from google.appengine.api import users
user = users.get_current_user()
userinfo = ndb.Key(UserInfo, user.user_id()).get()
watched_movies = UsersChoices.get_watched_movies(userinfo.key.id())
liked_movies = UsersChoices.get_liked_movies(userinfo.key.id())
It appears you are trying to model a many-to-many relationship. There are a few ways to model this relationship (see the Many-to-Many section). See also Nick's blog. (Unfortunately, neither of those references are written for NDB, so, for example, you can't use collection_name, i.e., back-references. But they are still useful in showing you how to break up the data into different models.)
Here's one way you could do it, using "join tables"/"relationship models":
class Movie(ndb.Model):
title = ndb.StringProperty(required=True)
class LikedMovie(ndb.Model):
movie = ndb.KeyProperty(kind=Movie, required=True)
user = ndb.StringProperty(required=True) # user.user_id()
class WatchedMovie(ndb.Model):
movie = ndb.KeyProperty(kind=Movie, required=True)
user = ndb.StringProperty(required=True) # user.user_id()
...
movies_user_likes = LikedMovie.query(LikedMovie.user == user.user_id()).fetch()
Depending on how many users your application will support, and how often the database will be updated, it may be more efficient to use repeated properties (i.e., lists of users) instead of join tables:
class Movie(ndb.Model):
title = ndb.StringProperty(required=True)
users_who_watched = ndb.StringProperty(repeated=True) # list of user.user_id()s
users_who_liked = ndb.StringProperty(repeated=True) # list of user.user_id()s
...
movies_user_likes = Movie.query(Movie.users_who_liked == user.user_id()).fetch(projection=[Movie.title])
Note that I used a projection query above, so that the users_who_watched lists are not returned with the query results. You probably don't need these, and this should make fetching significantly faster.
If you expect, say, less than 1,000 users to watch or like a particular movie, the list approach might be better.
For a more advanced technique, see Building Scalable, Complex Apps on App Engine, where Brett shows how to move the repeated/list property into a separate model, using parent keys.