I'd like to have a Django form which accepts a bitcoin address from a user. What would be the best way to validate whether or not this address is legitimate?
I could try writing my own implementation, but in regards to these things I'm assuming it's always better to go with something tried and tested than create something with potential holes. Is there good python code I can use to make a custom field for my django forms, or any resources that have already done this?
Alternatively, might it be better to perhaps skip the whole custom form field process, for example, and validate the address in the view using a pycoin library instead? If I were to do it this way, however, how would I return the error in the form?
BCAddressField acomplishes exactly what I was looking for. Note however that you must replace from django.forms.util import ValidationError with from django.core.exceptions import ValidationError, as the former is deprecated.
Bech32:
def btc_validation(address):
a = str(address)
length = 0
valid = False
not_btc = False
for i in a:
length += 1
if length == 42:
if a[2] == '1' and a[0] == 'b' and a[1] == 'c':
for i in a:
if i == 'O' or i == 'I':
not_btc = True
break
if not_btc == True:
return valid
else:
valid = True
return valid
else:
return 'didn\'t start with bc1'
else:
return 'it\'s short'
P2PKH:
import base58
def bitcoin_address_validation(bitcoinAddress):
"""
Base58 (P2PKH)
"""
try:
base58Decoder = base58.b58decode(bitcoinAddress).hex()
prefixAndHash = base58Decoder[:len(base58Decoder) - 8]
checksum = base58Decoder[len(base58Decoder) - 8:]
hash = prefixAndHash
for x in range(1, 3):
hash = hashlib.sha256(binascii.unhexlify(hash)).hexdigest()
if (checksum == hash[:8]):
valid = True
else:
valid = False
except:
valid = False
pass
return valid
Reference
Related
I have some code that checks if two string matches and they do in the database, but when I query them using this code
r = Usertasks.objects.all().filter(user=request.user).filter(randomURL=payment_id).values_list("TaskPostedToNetwork", flat=True)
e = Usertasks.objects.all().filter(user=request.user).filter(randomURL=payment_id).values_list("PaymentConfirmed", flat=True)
It returns
<QuerySet [False]>
<QuerySet ['yes']>
My if loop that checks for the string is never ran because it doesnt return as a string but with the queryset around it, I guess
if r == "False" and e == "yes":
print("Works")
How do I make it return just
False
yes
I'm assuming your query is intended to return just a single value. ie: user and randomURL are unique together. In that case:
task = Usertasks.objects.get(user=request.user, randomURL=payment_id)
if not task.TaskPostedToNetwork and task.PaymentConfirmed == 'yes':
print("Works")
Is there a way of changing the values of a constraint as the solver is running?
Basically, I have a constraint that depends on the value of a variable. The problem is that the constraint is evaluated based on the initial value of the variable, but isn't updated as the variable changes.
Here's a simple example:
from pyomo.environ import *
from pyomo.opt import SolverFactory
import numpy as np
# Setup
model = ConcreteModel()
model.A = Set(initialize = [0,1,2])
model.B = Set(initialize = [0,1,2])
model.x = Var(model.A, model.B, initialize=0)
# A constraint that I'd like to keep updating, based on the value of x
def changing_constraint_rule(model, a):
x_values = list((model.x[a, b].value for b in model.B))
if np.max(x_values) == 0:
return Constraint.Skip
else:
# Not really important what goes here, just as long as it updates the constraint list
if a == 1 : return sum(model.x[a,b] for b in model.B) == 0
else: return sum(model.x[a,b] for b in model.B) == 1
model.changing_constraint = Constraint(model.A, rule = changing_constraint_rule)
# Another constraint that changes the value of x
def bounding_constraint_rule(model, a):
return sum(model.x[a, b] for b in model.B) == 1
model.bounding_constraint = Constraint(
model.A,
rule = bounding_constraint_rule)
# Some objective function
def obj_rule(model):
return(sum(model.x[a,b] for a in model.A for b in model.B))
model.objective = Objective(rule=obj_rule)
# Results
opt = SolverFactory("glpk")
results = opt.solve(model)
results.write()
model.x.display()
If I run model.changing_constraint.pprint() I can see that no constraints have been made, since the initial value of the variable model.x was set to 0.
If it's not possible to change the constraint values while solving, how could I formulate this problem differently to achieve what I'm looking for? I've read this other post but couldn't figure it out from the instructions.
I am giving you the same answer in the other question by #Gabe:
Any if-logic you use inside of rules should not involve the values of
variables (unless it is based on the initial value of a variable, in
which case you would wrap the variable in value() wherever you use it
outside of the main expression that is returned).
for example:
model.x[a, b].value should be model.x[a, b].value()
But still this might not give you the solution what you are looking for.
In Django admin, if I want to display a list of Iron and their respective formatted weights, I would have to do this.
class IronAdmin(admin.ModelAdmin):
model = Iron
fields = ('weight_formatted',)
def weight_formatted(self, object):
return '{0:.2f} Kg'.format(object.weight)
weight_formatted.short_description = 'Weight'
I.e: 500.00 Kg
The problem with this however is that I would have to write a method for every field that I want to format, making it redundant when I have 10 or more objects to format.
Is there a method that I could override to "catch" these values and specify formatting before they get rendered onto the html? I.e. instead of having to write a method for each Admin class, I could just write the following and have it be formatted.
class IronAdmin(admin.ModelAdmin):
model = Iron
fields = ('weight__kg',)
def overriden_method(field):
if field.name.contains('__kg'):
field.value = '{0:.2f} Kg'.format(field.value)
I.e: 500.00 Kg
After hours scouring the source , I finally figured it out! I realize this isn't the most efficient code and it's probably more trouble than it's worth in most use cases but it's enough for me. In case anyone else needs a quick and dirty way to do it:
In order to automate it, I had to override django.contrib.admin.templatetags.admin_list.result_list with the following:
def result_list_larz(cl):
"""
Displays the headers and data list together
"""
resultz = list(results(cl)) # Where we override
""" Overriding starts here """
""" Have to scrub the __kg's as result_header(cl) will error out """
for k in cl.list_display:
cl.list_display[cl.list_display.index(k)] = k.replace('__kg','').replace('__c','')
headers = list(result_headers(cl))
num_sorted_fields = 0
for h in headers:
if h['sortable'] and h['sorted']:
num_sorted_fields += 1
return {'cl': cl,
'result_hidden_fields': list(result_hidden_fields(cl)),
'result_headers': headers,
'num_sorted_fields': num_sorted_fields,
'results': resultz}
Then overriding results(cl)'s call to items_for_result() wherein we then override its call to lookup_field() as follows:
def lookup_field(name, obj, model_admin=None):
opts = obj._meta
try:
f = _get_non_gfk_field(opts, name)
except (FieldDoesNotExist, FieldIsAForeignKeyColumnName):
# For non-field values, the value is either a method, property or
# returned via a callable.
if callable(name):
attr = name
value = attr(obj)
elif (model_admin is not None and
hasattr(model_admin, name) and
not name == '__str__' and
not name == '__unicode__'):
attr = getattr(model_admin, name)
value = attr(obj)
""" Formatting code here """
elif '__kg' in name or '__c' in name: # THE INSERT FOR FORMATTING!
actual_name = name.replace('__kg','').replace('__c', '')
value = getattr(obj, actual_name)
value = '{0:,.2f}'.format(value)
prefix = ''
postfix = ''
if '__kg' in name:
postfix = ' Kg'
elif '__c' in name:
prefix = 'P'
value = '{}{}{}'.format(prefix, value, postfix)
attr = value
else:
attr = getattr(obj, name)
if callable(attr):
value = attr()
else:
value = attr
f = None
""" Overriding code END """
else:
attr = None
value = getattr(obj, name)
return f, attr, value
I'm trying to get the next and previous objects of a comic book issue. Simply changing the id number or filtering through date added is not going to work because I don't add the issues sequentially.
This is how my views are setup and it WORKS for prev_issue and does return the previous object, but it returns the last object for next_issue and I do not know why.
def issue(request, issue_id):
issue = get_object_or_404(Issue, pk=issue_id)
title = Title.objects.filter(issue=issue)
prev_issue = Issue.objects.filter(title=title).filter(number__lt=issue.number)[0:1]
next_issue = Issue.objects.filter(title=title).filter(number__gt=issue.number)[0:1]
Add an order_by clause to ensure it orders by number.
next_issue = Issue.objects.filter(title=title, number__gt=issue.number).order_by('number').first()
I know this is a bit late, but for anyone else, django does have a nicer way to do this, see https://docs.djangoproject.com/en/1.7/ref/models/instances/#django.db.models.Model.get_previous_by_FOO
So the answer here would be something something like
next_issue = Issue.get_next_by_number(issue, title=title)
Django managers to do that with a bit of meta class cleaverness.
If it's required to find next and previous objects ordered by field values that can be equal and those fields are not of Date* type, the query gets slightly complex, because:
ordering on objects with same values limiting by [:1] will always produce same result for several objects;
object can itself be included in resulting set.
Here's are querysets that also take into account the primary keys to produce a correct result (assuming that number parameter from OP is not unique and omitting the title parameter as it's irrelevant for the example):
Previous:
prev_issue = (Issue.objects
.filter(number__lte=issue.number, id__lt=instance.id)
.exclude(id=issue.id)
.order_by('-number', '-id')
.first())
Next:
next_issue = (Issue.objects
.filter(number__gte=issue.number, id__gt=instance.id)
.exclude(id=issue.id)
.order_by('number', 'id')
.first())
from functools import partial, reduce
from django.db import models
def next_or_prev_instance(instance, qs=None, prev=False, loop=False):
if not qs:
qs = instance.__class__.objects.all()
if prev:
qs = qs.reverse()
lookup = 'lt'
else:
lookup = 'gt'
q_list = []
prev_fields = []
if qs.query.extra_order_by:
ordering = qs.query.extra_order_by
elif qs.query.order_by:
ordering = qs.query.order_by
elif qs.query.get_meta().ordering:
ordering = qs.query.get_meta().ordering
else:
ordering = []
ordering = list(ordering)
if 'pk' not in ordering and '-pk' not in ordering:
ordering.append('pk')
qs = qs.order_by(*ordering)
for field in ordering:
if field[0] == '-':
this_lookup = (lookup == 'gt' and 'lt' or 'gt')
field = field[1:]
else:
this_lookup = lookup
q_kwargs = dict([(f, get_model_attr(instance, f))
for f in prev_fields])
key = "%s__%s" % (field, this_lookup)
q_kwargs[key] = get_model_attr(instance, field)
q_list.append(models.Q(**q_kwargs))
prev_fields.append(field)
try:
return qs.filter(reduce(models.Q.__or__, q_list))[0]
except IndexError:
length = qs.count()
if loop and length > 1:
return qs[0]
return None
next_instance = partial(next_or_prev_instance, prev=False)
prev_instance = partial(next_or_prev_instance, prev=True)
note that do not use object.get(pk=object.pk + 1) these sorts of things, IntegrityError occurs if object at that pk is deleted, hence always use a query set
for visitors:
''' Useage '''
"""
# Declare our item
store = Store.objects.get(pk=pk)
# Define our models
stores = Store.objects.all()
# Ask for the next item
new_store = get_next_or_prev(stores, store, 'next')
# If there is a next item
if new_store:
# Replace our item with the next one
store = new_store
"""
''' Function '''
def get_next_or_prev(models, item, direction):
'''
Returns the next or previous item of
a query-set for 'item'.
'models' is a query-set containing all
items of which 'item' is a part of.
direction is 'next' or 'prev'
'''
getit = False
if direction == 'prev':
models = models.reverse()
for m in models:
if getit:
return m
if item == m:
getit = True
if getit:
# This would happen when the last
# item made getit True
return models[0]
return False
original author
Usage
# you MUST call order by to pass in an order, otherwise QuerySet.reverse will not work
qs = Model.objects.all().order_by('pk')
q = qs[0]
prev = get_next_or_prev(qs, q, 'prev')
next = get_next_or_prev(qs, q, 'next')
next_obj_id = int(current_obj_id) + 1
next_obj = Model.objects.filter(id=next_obj_id).first()
prev_obj_id= int(current_obj_id) - 1
prev_obj = Model.objects.filter(id=prev_obj_id).first()
#You have nothing to loose here... This works for me
I've got this complex filtering mechanism...
d = copy(request.GET)
d.setdefault('sort_by', 'created')
d.setdefault('sort_dir', 'desc')
form = FilterShipmentForm(d)
filter = {
'status': ShipmentStatuses.ACTIVE
}
exclude = {}
if not request.user.is_staff:
filter['user__is_staff'] = False
if request.user.is_authenticated():
exclude['user__blocked_by__blocked'] = request.user
if form.is_valid():
d = form.cleaned_data
if d.get('pickup_city'): filter['pickup_address__city__icontains'] = d['pickup_city']
if d.get('dropoff_city'): filter['dropoff_address__city__icontains'] = d['dropoff_city']
if d.get('pickup_province'): filter['pickup_address__province__exact'] = d['pickup_province']
if d.get('dropoff_province'): filter['dropoff_address__province__exact'] = d['dropoff_province']
if d.get('pickup_country'): filter['pickup_address__country__exact'] = d['pickup_country']
if d.get('dropoff_country'): filter['dropoff_address__country__exact'] = d['dropoff_country']
if d.get('min_price'): filter['target_price__gte'] = d['min_price']
if d.get('max_price'): filter['target_price__lte'] = d['max_price']
if d.get('min_distance'): filter['distance__gte'] = d['min_distance'] * 1000
if d.get('max_distance'): filter['distance__lte'] = d['max_distance'] * 1000
if d.get('available_on'): # <--- RELEVANT BIT HERE ---
filter['pickup_earliest__lte'] = d['available_on'] # basically I want "lte OR none"
filter['pickup_latest__gte'] = d['available_on']
if d.get('shipper'): filter['user__username__iexact'] = d['shipper']
order = ife(d['sort_dir'] == 'desc', '-') + d['sort_by']
shipments = Shipment.objects.filter(**filter).exclude(**exclude).order_by(order) \
.annotate(num_bids=Count('bids'), min_bid=Min('bids__amount'), max_bid=Max('bids__amount'))
And now my client tells me he wants pickup/drop-off dates to be 'flexible' as an option. So I've updated the DB to allow dates to be NULL for this purpose, but now the "available for pickup on" filter won't work as expected. It should include NULL/None dates. Is there an easy fix for this?
Flip the logic and use exclude(). What you really want to do is exclude any data that specifies a date that doesn't fit. If pickup_latest and pickup_earliest are NULL it shouldn't match the exclude query and wont be removed. Eg
exclude['pickup_latest__lt'] = d['available_on']
exclude['pickup_earliest__gt'] = d['available_on']
Most database engines don't like relational comparisons with NULL values. Use <field>__isnull to explicitly check if a value is NULL in the database, but you'll need to use Q objects to OR the conditions together.
Don't think that's actually a django-specific question. Variable 'd' is a python dictionary, no? If so, you can use this:
filter['pickup_latest__gte'] = d.get('available_on', None)