Previously, I have the following entity
class User(ndb.Model):
name = ndb.StringProperty(required = True)
timestamp = ndb.DateTimeProperty(required = True)
I use name as id, by written my code in the following way
user = User.get_or_insert(name, name=name,
timestamp=datetime.datetime.fromtimestamp(user_timestamp))
By having name as id, I can perform fast read or update using name.
Now, I decide to change my entity to the following, and have both name and type as composite id.
class User(ndb.Model):
name = ndb.StringProperty(required = True)
type = ndb.StringProperty(required = True)
timestamp = ndb.DateTimeProperty(required = True)
After referring https://stackoverflow.com/a/5454623/72437
My first thought is, by concatenation both name and type, it achieve my composite id purpose.
user = User.get_or_insert(name+type, name=name, type=type
timestamp=datetime.datetime.fromtimestamp(user_timestamp))
Soon, I realize this idea is flaw. As the following situation will create conflicting.
name type id
-------------------------
cheok paid cheokpaid
cheokp aid cheokpaid
2 different users end up with same id.
I was wondering, what is the proper way for me
To have composite id based on name and type
Have fast read or update, using name and type
Why not just use a separator while concatenating name and type. Then your code will work as is and solve your problem.
For example if you use '_' as your separator then
cheok paid become cheok_paid and
cheokp aid become cheokp_aid
One feature I have been struggling to implement in flask-admin is when the user edits a form, to constrain the value of Field 2 once Field 1 has been set.
Let me give a simplified example in words (the actual use case is more convoluted). Then I will show a full gist that implements that example, minus the "constrain" feature.
Let's say we have a database that tracks some software "recipes" to output reports in various formats. The recipe table of our sample database has two recipes: "Serious Report", "ASCII Art".
To implement each recipe, we choose one among several methods. The method table of our database has two methods: "tabulate_results", "pretty_print".
Each method has parameters. The methodarg table has two parameter names for "tabulate_results" ("rows", "display_total") and two parameters for "pretty_print" ("embellishment_character", "lines_to_jump").
Now for each of the recipes ("Serious Report", "ASCII Art") we need to provide the value of the arguments of their respective methods ("tabulate_results", "pretty_print").
For each record, the recipearg table lets us select a recipe (that's Field 1, for instance "Serious Report") and an argument name (that's Field 2). The problem is that all possible argument names are shown, whereas they need to be constrained based on the value of Field 1.
What filtering / constraining mechanism can we implement such that once we select "Serious Report", we know we will be using the "tabulate_results" method, so that only the "rows" and "display_total" arguments are available?
I'm thinking some AJAX wizardry that checks Field 1 and sets a query for Field 2 values, but have no idea how to proceed.
You can see this by playing with the gist: click on the Recipe Arg tab. In the first row ("Serious Report"), if you try to edit the "Methodarg" value by clicking on it, all four argument names are available, instead of just two.
# full gist: please run this
from flask import Flask
from flask_admin import Admin
from flask_admin.contrib import sqla
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import Column, ForeignKey, Integer, String
from sqlalchemy.orm import relationship
# Create application
app = Flask(__name__)
# Create dummy secrey key so we can use sessions
app.config['SECRET_KEY'] = '123456790'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///a_sample_database.sqlite'
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)
# Create admin app
admin = Admin(app, name="Constrain Values", template_mode='bootstrap3')
# Flask views
#app.route('/')
def index():
return 'Click me to get to Admin!'
class Method(db.Model):
__tablename__ = 'method'
mid = Column(Integer, primary_key=True)
method = Column(String(20), nullable=False, unique=True)
methodarg = relationship('MethodArg', backref='method')
recipe = relationship('Recipe', backref='method')
def __str__(self):
return self.method
class MethodArg(db.Model):
__tablename__ = 'methodarg'
maid = Column(Integer, primary_key=True)
mid = Column(ForeignKey('method.mid', ondelete='CASCADE', onupdate='CASCADE'), nullable=False)
methodarg = Column(String(20), nullable=False, unique=True)
recipearg = relationship('RecipeArg', backref='methodarg')
inline_models = (Method,)
def __str__(self):
return self.methodarg
class Recipe(db.Model):
__tablename__ = 'recipe'
rid = Column(Integer, primary_key=True)
mid = Column(ForeignKey('method.mid', ondelete='CASCADE', onupdate='CASCADE'), nullable=False)
recipe = Column(String(20), nullable=False, index=True)
recipearg = relationship('RecipeArg', backref='recipe')
inline_models = (Method,)
def __str__(self):
return self.recipe
class RecipeArg(db.Model):
__tablename__ = 'recipearg'
raid = Column(Integer, primary_key=True)
rid = Column(ForeignKey('recipe.rid', ondelete='CASCADE', onupdate='CASCADE'), nullable=False)
maid = Column(ForeignKey('methodarg.maid', ondelete='CASCADE', onupdate='CASCADE'), nullable=False)
strvalue = Column(String(80), nullable=False)
inline_models = (Recipe, MethodArg)
def __str__(self):
return self.strvalue
class MethodArgAdmin(sqla.ModelView):
column_list = ('method', 'methodarg')
column_editable_list = column_list
class RecipeAdmin(sqla.ModelView):
column_list = ('recipe', 'method')
column_editable_list = column_list
class RecipeArgAdmin(sqla.ModelView):
column_list = ('recipe', 'methodarg', 'strvalue')
column_editable_list = column_list
admin.add_view(RecipeArgAdmin(RecipeArg, db.session))
# More submenu
admin.add_view(sqla.ModelView(Method, db.session, category='See Other Tables'))
admin.add_view(MethodArgAdmin(MethodArg, db.session, category='See Other Tables'))
admin.add_view(RecipeAdmin(Recipe, db.session, category='See Other Tables'))
if __name__ == '__main__':
db.drop_all()
db.create_all()
db.session.add(Method(mid=1, method='tabulate_results'))
db.session.add(Method(mid=2, method='pretty_print'))
db.session.commit()
db.session.add(MethodArg(maid=1, mid=1, methodarg='rows'))
db.session.add(MethodArg(maid=2, mid=1, methodarg='display_total'))
db.session.add(MethodArg(maid=3, mid=2, methodarg='embellishment_character'))
db.session.add(MethodArg(maid=4, mid=2, methodarg='lines_to_jump'))
db.session.add(Recipe(rid=1, mid=1, recipe='Serious Report'))
db.session.add(Recipe(rid=2, mid=2, recipe='ASCII Art'))
db.session.commit()
db.session.add(RecipeArg(raid=1, rid=1, maid=2, strvalue='true' ))
db.session.add(RecipeArg(raid=2, rid=1, maid=1, strvalue='12' ))
db.session.add(RecipeArg(raid=3, rid=2, maid=4, strvalue='3' ))
db.session.commit()
# Start app
app.run(debug=True)
I see two ways of tacking this problem:
1- When Flask-Admin generate the form, add data attributes with the mid of each methodArg on each option tag in the methodArg select. Then have some JS code filter the option tags based on the recipe selected.
EDIT
Here is a tentative try at putting a data-mid attribute on each option:
def monkeypatched_call(self, field, **kwargs):
kwargs.setdefault('id', field.id)
if self.multiple:
kwargs['multiple'] = True
html = ['<select %s>' % html_params(name=field.name, **kwargs)]
for (val, label, selected), (_, methodarg) in zip(field.iter_choices(), field._get_object_list()):
html.append(self.render_option(val, label, selected, **{'data-mid': methodarg.mid}))
html.append('</select>')
return HTMLString(''.join(html))
Select.__call__ = monkeypatched_call
The blocker is in the fact that those render calls are triggered from the jinja templates, so you are pretty much stuck updating a widget (Select being the most low-level one in WTForms, and is used as a base for Flask-Admin's Select2Field).
After getting those data-mid on each of your options, you can proceed with just binding an change on your recipe's select and display the methodarg's option that have a matching data-mid. Considering Flask-Admin uses select2, you might have to do some JS tweaking (easiest ugly solution would be to clean up the widget and re-create it for each change event triggered)
Overall, I find this one less robust than the second solution. I kept the monkeypatch to make it clear this should not be used in production imho. (the second solution is slightly less intrusive)
2- Use the supported ajax-completion in Flask-Admin to hack your way into getting the options that you want based on the selected recipe:
First, create a custom AjaxModelLoader that will be responsible for executing the right selection query to the DB:
class MethodArgAjaxModelLoader(sqla.ajax.QueryAjaxModelLoader):
def get_list(self, term, offset=0, limit=10):
query = self.session.query(self.model).filter_by(mid=term)
return query.offset(offset).limit(limit).all()
class RecipeArgAdmin(sqla.ModelView):
column_list = ('recipe', 'methodarg', 'strvalue')
form_ajax_refs = {
'methodarg': MethodArgAjaxModelLoader('methodarg', db.session, MethodArg, fields=['methodarg'])
}
column_editable_list = column_list
Then, update Flask-Admin's form.js to get the browser to send you the recipe information instead of the methodArg name that needs to be autocompleted. (or you could send both in query and do some arg parsing in your AjaxLoader since Flask-Admin does no parsing whatsoever on query, expecting it to be a string I suppose [0]. That way, you would keep the auto-completion)
data: function(term, page) {
return {
query: $('#recipe').val(),
offset: (page - 1) * 10,
limit: 10
};
},
This snippet is taken from Flask-Admin's form.js [1]
Obviously, this needs some tweaking and parametrising (because doing such a hacky solution would block you from using other ajax-populated select in the rest of your app admin + the update on form.js directly like that would make upgrading Flask-Admin extremely cumbersome)
Overall, I am unsatisfied with both solutions and this showcase that whenever you want to go out of the tracks of a framework / tool, you can end up in complex dead ends. This might be an interesting feature request / project for someone willing to contribute a real solution upstream to Flask-Admin though.
There is another easy solution that I made and it works
1- Create your first select option normally with data loaded on it and add a hook to it which will add js event listener when it selects change like this.
from wtforms import SelectField
form_extra_fields = {
'streetname': SelectField(
'streetname',
coerce=str,
choices=([street.streetname for street in StreetsMetadata.query.all()]),
render_kw={'onchange': "myFunction()"}
)
}
**2- Add a JavaScript URL file to the view you want to use this function in, for example.
def render(self, template, **kwargs):
#using extra js in render method allow use url_for that itself requires an app context
self.extra_js = [url_for("static", filename="admin/js/users.js")]
response = render_miror(self, template,**kwargs)
return response
3- Create a role-protected endpoint that you used for this view that will accept a GET request from JS based on the first value specified for the entry, for example this route returns a list of house numbers by querying the street name that came from the first entry
#super_admin_permission.require(http_exception=403)
#adminapp.route('/get_houses_numbers')
def gethouses():
request_data = request.args
if request_data and 'street' in request_data:
street = StreetsMetadata.query.filter(StreetsMetadata.streetname == request_data['street']).one_or_none()
street_houses = lambda:giveMeAllHousesList(street.excluded, street.min, street.max)
if street_houses:
return jsonify({'code': 200, 'houses': street_houses()})
else:
return jsonify({'code': 404, 'houses': []})
else:
return jsonify({'code': 400, 'street': []})
now python part completed time for JavaScript
4- We have to define three functions, the first of which will be called when the form build page is loaded and which do two things first,
A dummy select entry will be created using JS and append that entry to the same string input container
Make string entry read-only to improve user experience
Second, it will send a GET request to the specified route to get a list of house numbers using the specified street input value
Then get the result and create the option elements and append these options to the dummy selection, you can also select the first option while appending the options.
5- The second function "myFunction" is the hook defined in Python in this part
render_kw={'onchange': "myFunction()"}
This function will do nothing new, it will only send a GET request when the first specified input value is changed, send a GET request to get a list of new house numbers based on the given street name input value by doing a query on the database, then dump the inner HTML of the dummy selection entry , then create and append new options to it.
6- The last function is the callback function which listens for the change on the dummy select entry created with JS when the user chooses the house number which will be reflected in the main string entry, finally you can click save and you will see it working
Note that this whole idea I created is not as good as the built in flask admin, but if you are looking for the end goal and without any problems you can use it
My JS code
/*
This Function when run when a form included it will create JS select input with the
default loaded streetname and add house number on that select this select will used
to guide creator of the house number or to select the house number
*/
async function onFlaskFormLoad(){
const streetSelect = document.querySelector("#streetname");
const checkIfForm = document.querySelector("form.admin-form");
if (checkIfForm){
let checkSelect = document.querySelector("#realSelect");
if (!checkSelect){
const mySelectBox = document.createElement("select");
const houseString = document.querySelector("#housenumber");
const houseStringCont = houseString.parentElement;
mySelectBox.classList.add("form-control")
mySelectBox.id = "realSelect";
houseStringCont.appendChild(mySelectBox);
mySelectBox.addEventListener("change", customFlaskAdminUnpredefinedSelect);
houseString.setAttribute("readonly", "readonly");
const res = await fetch(`/get_houses_numbers?street=${streetSelect.value}`);
const data = await res.json();
console.log(data);
if (data.code == 200 && mySelectBox){
data.houses.forEach( (houseOption, index)=>{
if (index == 0){
houseString.value = houseOption;
}
let newHouse = document.createElement("option");
newHouse.setAttribute("value", houseOption);
newHouse.innerText = houseOption;
mySelectBox.appendChild(newHouse);
});
}
}
}
}
onFlaskFormLoad();
/*
this function will called to change the string input value to my custom js select
value and then use that string to house number which required by flask-admin
*/
function customFlaskAdminUnpredefinedSelect(){
const theSelect = document.querySelector("#realSelect");
const houseString = document.querySelector("#housenumber");
houseString.value = theSelect.value;
return true;
}
/*
flask admin hook that will listen on street input change and then it will send
get request to secured endpoint with role superadmin required and get the housenumbers
using the streetname selected and then create options and add to my select input
*/
async function myFunction(){
const streetSelect = document.querySelector("#streetname");
const houseString = document.querySelector("#housenumber");
const houseStringCont = houseString.parentElement;
const theSelect = document.querySelector("#realSelect");
const res = await fetch(`/get_houses_numbers?street=${streetSelect.value}`);
const data = await res.json();
console.log(data);
if (data.code == 200 && theSelect){
theSelect.innerHTML = "";
data.houses.forEach( (houseOption, index)=>{
if (index == 0){
houseString.value = houseOption;
}
let newHouse = document.createElement("option");
newHouse.setAttribute("value", houseOption);
newHouse.innerText = houseOption;
theSelect.appendChild(newHouse);
});
}
}
Now if I change the street name of the first specified input I will get a new list containing the numbers based on the first input value, note if you have a way to create a python field that accepts the non-predefined options then there is no need to create dummy input you can create and append the new options Directly to second select input
final result
I have an API from which I receive a query. This API is in Python.
I call it from a django app (views.py). Then, I want to query my MongoDB collection, using mongoengine:
api_response = requests.get("http://*******", {'query':query}) #We call the API
json_resp = api_response.json()
person = Person.objects(__raw__=json_resp).to_json() #We search for the json_query in the DB (raw) and the output is JSON
It works fine but I have a problem with dates... Indeed, my Person model is as follow:
class Person(DynamicDocument):
# Meta Variables
meta = {
'collection':'personsExample'
}
#Document variables
PersonID = models.CharField(max_length = 6)
FirstName = models.CharField(max_length = 50)
LastName = models.CharField(max_length = 50)
Gender = models.CharField(max_length = 6) #male/female
BirthDate = models.DateField()
CitizenCountryCode = models.CharField(max_length = 2)
My personsExample collection was imported via mongoimport from a CSV file:
mongoimport --host localhost --db persons --collection personsExample --type csv --file reducedPersonsExtract.csv --headerline
As the birth dates were set as string, I have converted them using:
db.personsExample.find().forEach(function(el){el.BirthDate = new ISODate(el.BirthDate); db.personsExample.save(el)})
The problem I have now is that it gives BirthDate field as follow:
"BirthDate" : ISODate("1970-12-21T00:00:00Z")
But in my json query, date is stored as
datetime.datetime(1970,12,21,0,0,0).isoformat()
Which gives:
{
"BirthDate": "1970-12-21T00:00:00"
}
Thus, the query doesn't work, I would need to make my query with
{
"BirthDate": ISODate"1970-12-21T00:00:00Z"
}
(But I can't create such objects (ISODate) with Python... )
Or to find another way to store the date in MongoDB.
Would you happen to know how I could solve my problem please?
I have succeeded to to what I wanted to. In fact, I don't convert dates to ISODate in the DB, I store them as string "YYYY-MM-DD". Then, I format the date in my API (which sends the JSON query to the App which uses MongoDB) :
my_dict['BirthDate'] = datetime.datetime(YYYY,MM,DD).isoformat()
Then, in my App :
json_resp = api_response.json() #Deserialization of the response
json_resp['BirthDate'] = datetime.datetime.strptime(json_resp['BirthDate'], "%Y-%m-%dT%H:%M:%S")
It may not be the best solution but it works.
I am using Redis Object Mapper(ROM) here.
This is my model
class User(rom.Model):
name = rom.String(required=True, unique=True)
nickname = rom.String(required=False)
photo = rom.String(required=False)
I am trying -
user1 = User(name="Ankush", nickname="iamkhush",
photo='http://graph.facebook.com/iamkhush/picture')
user1.save()
I get the result when I do
user = User.get(1) #user is a model instance
But when I do
user_obj = User.query.filter(name='Ankush').execute()
I get [ ] (An empty result)
Cant get why is this happening?
There are two parts to this. First, you don't need to use the index if you want to get an item by a column defined with unique=True, but the query is different. Using unique=True and index=False, you can get the item by using the User.get_by() form:
>>> User.get_by(name="Ankush")
<__main__.User object at 0x87070cc>
The primary limitation being that you must pass the full column exactly as it is defined in the column. This is generally useful for keeping unique email addresses (lowercase them first!), usernames (be careful with your capitalization), and other examples.
The second part is that when enabling the index, the index has "case-insensitive unique bag-of-words" semantics for string/text columns (I come from the search engine side of the world, which has substantially different (and arguably better) semantics than typical db queries). So if you want to find entries, you need to use:
>>> class User(rom.Model):
... name = rom.String(required=True, unique=True, index=True)
... nickname = rom.String(required=False)
... photo = rom.String(required=False)
...
>>> user1 = User(name="Ankush", nickname="iamankush", photo="http://graph.facebook.com/iamkhush/picture")
>>> user1.save()
>>> User.query.filter(name="ankush").all()
[<__main__.User object at 0x870738c>]
(also note that .execute() is an alias for .all() ).
If you want to change the case-sensitivity or other behavior with columns defined with index=True, you need to pass a custom keygen argument (you can see rom.util._string_keygen() at https://github.com/josiahcarlson/rom/blob/master/rom/util.py#L149 for rom.String and rom.Text key generation semantics).
You need to pass index=True along with name to allow it to be queried by filter.
class User(rom.Model):
name = rom.Text(required=True, unique=True,index = True,keygen=text_keyge)
nickname = rom.String(required=False)
photo = rom.String(required=False)
I'm trying to save data from a facebook graph query, which returns location info in the format:
friend: {
location: {
id: "106078429431815",
name: "London, United Kingdom"
},
}
Or the location key is missing entirely if the user hasn't set that variable, or it's set to 'null'.
The location field in the Model is defined as:
location = models.CharField(max_length=255, blank=True, null=True)
I'm storing the data in the model using the following code, which caters for both the initial query to create the record as well as updates just in case values change in the future:
friend = get_facebook_friend(friend_id=friend_id)
try:
location_name = data['location'].get('name', '')
except:
location_name = ''
if friend:
friend.name = data['name']
friend.location = location_name,
friend.full_clean()
friend.save()
else:
friend = Friend(
name=data['name'],
location=location_name)
friend.full_clean()
friend.save()
This seems to work pretty well for the first insert, which stores values for the Location column in the database as:
- 'London, United Kingdom'
- ''
- NULL
However on subsequent updates, this is storing strange results in the database table, for instance:
(u'London, United Kingdom',)
('',)
(None,)
This same behavior is not observed in other CharFields storing strings from Facebook queries
I'm quite confused D:, Help!
due to the tailing comma:
friend.location = location_name,
assigns the tuple (location_name, ) (the brackets are optional)
to friend.location