I want to implement some kind of tagging functionality to my app. I want to do something like...
class Item(db.Model):
name = db.StringProperty()
tags = db.ListProperty(str)
Suppose I get a search that have 2 or more tags. Eg. "restaurant" and "mexican".
Now, I want to get Items that have ALL, in this case 2, given tags.
How do I do that? Or is there a better way to implement what I want?
I believe you want tags to be stored as 'db.ListProperty(db.Category)' and then query them with something like:
return db.Query(Item)\
.filter('tags = ', expected_tag1)\
.filter('tags = ', expected_tag2)\
.order('name')\
.fetch(256)
(Unfortunately I can't find any good documentation for the db.Category type. So I cannot definitively say this is the right way to go.) Also note, that in order to create a db.Category you need to use:
new_item.tags.append(db.Category(unicode(new_tag_text)))
use db.ListProperty(db.Key) instead,which stores a list of entity's keys.
models:
class Profile(db.Model):
data_list=db.ListProperty(db.Key)
class Data(db.Model):
name=db.StringProperty()
views:
prof=Profile()
data=Data.gql("")#The Data entities you want to fetch
for data in data:
prof.data_list.append(data)
/// Here data_list stores the keys of Data entity
Data.get(prof.data_list) will get all the Data entities whose key are in the data_list attribute
Related
How to create ArrayField() in TortoiseORM
from common.base_model import AbstractBaseModel
from tortoise.fields import CharField, BooleanField, ForeignKeyField, ArrayField
class City(AbstractBaseModel):
name = CharField(max_length=100, unique=True)
district = CharField(max_length=100, null=True)
state = CharField(max_length=100)
country = ArrayField() # not working
is_verified = BooleanField(default=True)
There is no ArrayField in TortoiseORM, here is an article about fields in TortoiseORM from its documentation.
As you can see, there is no matching field in TortoiseORM, so you have to extend the existing field class.
I suggest extending the basic class Field because your subclass' to_db_value method has to return the same type as extended field class' to_db_value method, and in the class Field it's not specified.
Next time, try harder - read the documentation and make better questions (add more info, show your attempts).
To achieve the result you want,which I'm assuming is having a field to hold multiple countries, you'd have to create another table for your country field and have a many to many relationship between that table and your city table,its a more conventional implementation that wont have you extend the existing field class.
I working on an application that has its own database and gets user information from another serivce (an LDAP is this case, through an API package).
Say I have a tables called Articles, with a column user_id. There is no Users table, instead a user or set of users is retrieved through the external API:
$user = LDAPConnector::getUser($user_id);
$users = LDAPConnector::getUsers([1, 2, 5, 6]);
Of course I want retrieving data from inside a controller to be as simple as possible, ideally still with something like:
$articles = $this->Articles->find()->contain('Users');
foreach ($articles as $article) {
echo $article->user->getFullname();
}
I'm not sure how to approach this.
Where should I place the code in the table object to allow integration with the external API?
And as a bonus question: How to minimise the number of LDAP queries when filling the Entities?
i.e. it seems to be a lot faster by first retrieving the relevant users with a single ->getUsers() and placing them later, even though iterating over the articles and using multiple ->getUser() might be simpler.
The most simple solution would be to use a result formatter to fetch and inject the external data.
The more sophisticated solution would a custom association, and a custom association loader, but given how database-centric associations are, you'd probably also have to come up with a table and possibly a query implementation that handles your LDAP datasource. While it would be rather simple to move this into a custom association, containing the association will look up a matching table, cause the schema to be inspected, etc.
So I'll stick with providing an example for the first option. A result formatter would be pretty simple, something like this:
$this->Articles
->find()
->formatResults(function (\Cake\Collection\CollectionInterface $results) {
$userIds = array_unique($results->extract('user_id')->toArray());
$users = LDAPConnector::getUsers($userIds);
$usersMap = collection($users)->indexBy('id')->toArray();
return $results
->map(function ($article) use ($usersMap) {
if (isset($usersMap[$article['user_id']])) {
$article['user'] = $usersMap[$article['user_id']];
}
return $article;
});
});
The example makes the assumption that the data returned from LDAPConnector::getUsers() is a collection of associative arrays, with an id key that matches the user id. You'd have to adapt this accordingly, depending on what exactly LDAPConnector::getUsers() returns.
That aside, the example should be rather self-explanatory, first obtain a unique list of users IDs found in the queried articles, obtain the LDAP users using those IDs, then inject the users into the articles.
If you wanted to have entities in your results, then create entities from the user data, for example like this:
$userData = $usersMap[$article['user_id']];
$article['user'] = new \App\Model\Entity\User($userData);
For better reusability, put the formatter in a custom finder. In your ArticlesTable class:
public function findWithUsers(\Cake\ORM\Query $query, array $options)
{
return $query->formatResults(/* ... */);
}
Then you can just do $this->Articles->find('withUsers'), just as simple as containing.
See also
Cookbook > Database Access & ORM > Query Builder > Adding Calculated Fields
Cookbook > Database Access & ORM > Retrieving Data & Results Sets > Custom Finder Methods
The question might sound a little bit confusing but I don't know how to explain it better in one sentence.
This describes basically what the problem is:
I have a Users table which can contain 2 types of users. I know how I can separate by role. But here's the thing, users with role 1(editor_in_chief) have different attributes than users with role 2(reviewer).
My idea was to create a table named 'reviewer_attributes' and 'editor_in_chief_attributes' and create a one-to-one relation with this table to hold the attributes for the users table.
Maybe you have a better idea, that would be great as well. But for this scenario, I would like to know if it is possible to make a call to the database and to get these users' properties from the other table as properties of the User object.
When using a DB call using relations laravel will give me something like this:
user {
id: 1,
name: "Name",
reviewer_attributes: {
attribute_1: 'attribute_1',
attribute_2: 'attribute_2',
attribute_3: 'attribute_3',
}
}
But this is what I want to object to obtain look like:
user {
id: 1,
name: "Name",
attribute_1: 'attribute_1',
attribute_2: 'attribute_2',
attribute_3: 'attribute_3',
}
I want to achieve this by a single database call instead of setting the properties after the call.
I find this a very interesting topic, I hope you could help!
If I got your problem right, you may call somthing like this:
DB::table('users')
->join('reviewer_attributes', 'users.id', '=', 'reviewer_attributes.user_id')
->find($id);
you may add select to get specific attributes of each table:
DB::table('users')
->join('reviewer_attributes', 'users.id', '=', 'reviewer_attributes.user_id')
->select('users.id', 'users.name', 'reviewer_attributes.*')
->find($id);
Update: You can also use collections to restructure your results returned by Eloquent:
$result = User::with('reviewerAttributes')->find($id);
$result = $result->get('reviewer_attributes')
->merge($result->forget('reviewer_attributes')->all())
->all();
You need export model to Json?
If so, override toArray method
public function toArray()
{
$arr = parent::toArray();
$reviewer_attributes = $this->getReviewerAttributesSomeHow();
return array_merge($arr, $reviewer_attributes);
}
I am trying to achieve a category model where name has unique=True,
but practically I can still add same category name with different cases.
i.e. I have a category called Food
I am still able to add food, FOOD, fOod, FOOd
Is their any philosophy behind this? or it is a work in progress.
Cause in real world if I think of Category Food, it will always be food, no matter what case it has used to mention itself.
Thank you in advance to look at this.
To answer my own question:
I have found I can have clean method on my model. So I added
class Category(models.Model):
name = models.CharField(max_length=200, unique=True)
def clean(self):
self.name = self.name.capitalize()
It is capitalising the first letter, which is then handled by the save method, which calls the validate_unique method to raise error.
You can use Postgre specific model field called Citext fields (case insensitive fields).
There are three option at the moment:
class CICharField(**options), class CIEmailField(**options) and class CITextField(**options)
Example:
from django.db import models
from django.contrib.postgres.fields import CICharField
class Category(models.Model):
name = CICharField(verbose_name="Name", max_length=255)
But don't forget to create an extension for the citext fields.
See here.
Basically, you have to add the extension class in the migration file, inside the operations array, before the first CreateModel operation.
# migration file
operations = [
CITextExtension(), # <------ here
migrations.CreateModel(
...
),
...,
]
Setting the column to case-insensitive collation should fix this. You may need to do it at the SQL level.
I have the following model structure
class User(db.Model) :
nickname = db.StringProperty(required=True)
fullname = db.StringProperty(required=True)
class Article(db.Model) :
title = db.StringProperty(required=True)
body = db.StringProperty(required=True)
author = db.ReferenceProperty(User, required=True)
class Favorite(db.Model) :
who = db.ReferenceProperty(User, required=True)
what = db.ReferenceProperty(Article, required=True)
I'd like to display 10 last articles according to this pattern: article.title, article.body, article.author(nickname), info if this article has been already favorited by the signed in user.
I have added a function which I use to get the authors of these articles using only one query (it is described here)
But I don't know what to do with the favorites (I'd like to know which of the displayed articles have been favorited by me using less than 10 queries (I want to display 10 articles)). Is it possible?
You can actually do this with an amortized cost of 0 queries if you denormalize your data more! Add a favorites property to Authors which stores a list of keys of articles which the user has favorited. Then you can determine if the article is the user's favorite by simply checking this list.
If you retrieve this list of favorites when the user first logs in and just store it in your user's session data (and update it when the user adds/removes a favorite), then you won't have to query the datastore to check to see if an item is a favorite.
Suggested update to the Authors model:
class Authors(db.Model): # I think this would be better named "User"
# same properties you already had ...
favorites = db.ListProperty(db.Key, required=True, default=[])
When the user logs in, just cache their list of favorites in your session data:
session['favs'] = user.favorites
Then when you show the latest articles, you can check if they are a favorite just by seeing if each article's key is in the favorites list you cached already (or you could dynamically query the favorites list but there is really no need to).
favs = session['favs']
articles = get_ten_latest_articles()
for article in articles:
if article.key() in favs:
# ...
I think there is one more solution.
Let's add 'auto increment' fields to the User and Article class.
Then, when we want to add an entry to the Favorite class, we will also add the key name in the format which we will be able to know having auto increment value of the signed in user and the article, like this 'UserId'+id_of_the_user+'ArticleId'+id_of_an_article.
Then, when it comes to display, we will easily predict key names of the favorites and would be able to use Favorite.get_by_key_name(key_names).
An alternative solution to dound's is to store the publication date of the favorited article on the Favorite entry. Then, simply sort by that when querying.