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  • Rails - undefined method `name' for nil:NilClass

    - by sscirrus
    Hi guys, Quick question. Here is my code: #routes map.resources :customers, :has_many => [:addresses, :matchings] map.connect ":controller/:action/:id" #url path: http://127.0.0.1:3000/customers/index/3 #customers controller def index @customer = Customer.find(params[:id]) end #customers view/index.html.erb ... <%= @customer.name %> ... Error: undefined method `name' for nil:NilClass. Here's my reasoning. The parameter :id is coming from my url path (i.e. we're looking for customer #3 in the above path). @customer should find that array easily, then @customer.name should produce the name, but apparently @customer is blank. Why? I assume the problem is that I'm not producing an array in my controller?

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  • Infinite recursion trying to check all elements of a TreeCtrl

    - by mavnn
    I have a TreeCtrl in which more than one Item can be assigned the same object as PyData. When the object is updated, I want to update all of the items in the tree which have that object as their PyData. I thought the following code would solve the problem quite neatly, but for some reason the logical test (current != self.GetFirstVisibleItem()) always returns true leading to infinite recursion. Can anyone explain why? def RefreshNodes(self, obj, current=None): print "Entered refresh" current = current or self.GetFirstVisibleItem() if current.IsOk(): print self.GetPyData(current).name if self.GetPyData(current) == obj: self.RefreshNode(current) current = self.GetNextVisible(current) if current != self.GetFirstVisibleItem(): self.RefreshNodes(obj, current) Edit: the above is obviously part of a class based on wx.TreeCtrl

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  • Add RESTful Action

    - by Drew Rush
    The source of my information is section 2.9 here: [http://guides.rubyonrails.org/routing.html#connecting-urls-to-code][1] What I'm trying to do is add a custom action "search" and corresponding view. So, as it says to do in the documentation, I've added this code in my config/routes.rb file: resources :dimensions do collection do get "search" end end I've also defined in the dimensions_controller file: def search @dimensions = Dimension.all respond_to do |format| format.html # search.html.erb format.json { render json: @dimensions } end end I then stopped and restarted the rails server, but when I navigate to /dimensions/home, I'm still getting this error message: Couldn't find Dimension with id=search Also showing that my parameter is: {"id"=>"search"} So am I just missing another bit of code that gives the instruction to interpret /dimension/search as a collection action as opposed to the show action? Thanks for your time.

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  • Fastest way to find the rotation of a vector

    - by kriss
    I have two 2D vectors, say u and v, defined by cartesian coordinates. Imagine that vectors are needles of a clock. I'm looking for the fastest way to find out, using python, if v is after or before u (or in other words find out in wich half plane is v, regarding to position of u). For the purpose of the problem if vectors are aligned answer should be before. It seems easy using some trigonometry, but I believe there should be a faster way using coordinates only. My test case: def after(u, v): """code here""" after((4,2), (6, 1)) : True after((4,2), (3, 3)) : False after((4,2), (2, 1)) : False after((4,2), (3, -3)) : True after((4,2), (-2, -5)) : True after((4,2), (-4, -2)) : False

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  • Calculating the null space of a matrix

    - by Ainsworth
    I'm attempting to solve a set of equations of the form Ax = 0. A is known 6x6 matrix and I've written the below code using SVD to get the vector x which works to a certain extent. The answer is approximately correct but not good enough to be useful to me, how can I improve the precision of the calculation? Lowering eps below 1.e-4 causes the function to fail. from numpy.linalg import * from numpy import * A = matrix([[0.624010149127497 ,0.020915658603923 ,0.838082638087629 ,62.0778180312547 ,-0.336 ,0], [0.669649399820597 ,0.344105317421833 ,0.0543868015800246 ,49.0194290212841 ,-0.267 ,0], [0.473153758252885 ,0.366893577716959 ,0.924972565581684 ,186.071352614705 ,-1 ,0], [0.0759305208803158 ,0.356365401030535 ,0.126682113674883 ,175.292109352674 ,0 ,-5.201], [0.91160934274653 ,0.32447818779582 ,0.741382053883291 ,0.11536775372698 ,0 ,-0.034], [0.480860406786873 ,0.903499596111067 ,0.542581424762866 ,32.782593418975 ,0 ,-1]]) def null(A, eps=1e-3): u,s,vh = svd(A,full_matrices=1,compute_uv=1) null_space = compress(s <= eps, vh, axis=0) return null_space.T NS = null(A) print "Null space equals ",NS,"\n" print dot(A,NS)

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  • C++ detecting end of file

    - by xbonez
    I have a C++ program that is reading in info from a file, that stores info seperated by "$$$$". An example of how the file looks is: abc bcd $$$$ def $$$$ qwe gfh $$$$ How can I detect the file has ended, without using the eof() function? I have it set like this, getline(sin,temp) if (temp=="$$$$") { } After reading the last set of four dollars, how can I check the next line to ensure another set of data isn't beginning, and that the file has ended? If the file has indeed ended, I plan on using a boolean flag to terminate the while loop.

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  • How to create an image from canvas data?

    - by Jakub Hampl
    In my application I am trying to save an arbitrary part of a rendered HTML canvas to an image file. In my Javascript I call ctx.getImageData(x, y, w, h) and pass the resulting object to my macruby code (though if you know a solution in objc I am also very interested). There I'm trying to create a NSBitmapImageRep object so that I can then save to an image format the user desires. This is my code so far (the function gets a WebScriptObject as it's argument): def setimagedata(d) w = d.valueForKey("width").to_i h = d.valueForKey("height").to_i data = Pointer.new(:char, d.valueForKey("data").valueForKey("length").to_i) d.valueForKey("data").valueForKey("length").to_i.times do |i| data[i] = d.valueForKey("data").webScriptValueAtIndex(i).to_i end puts "data complete" # get's called @exported_image = NSBitmapImageRep.alloc.initWithBitmapDataPlanes(data, pixelsWide: w, pixelsHigh:h, bitsPerSample: 32, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSCalibratedRGBColorSpace, bitmapFormat: NSAlphaNonpremultipliedBitmapFormat, bytesPerRow: 0, bitsPerPixel: 0) puts "done" # doesn't get called end The code doesn't seem to get through the initWithBitmapDataPlanes function but gives no error. My question is: what am I doing wrong? Is this approach reasonable (if not, what would be better?).

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  • Saving data in a inherited django model

    - by aldeano
    I'm building an app to save data and some calculations made with those datas, the idea is keep the data in one model and the calculations in other. So, the models are like this: class FreshData(models.Model): name = models.CharField(max_length=20) one = models.IntegerField() two = models.IntegerField() def save(self, *args, **kwargs): Calculations() Calculations.three = self.one + self.two super(FreshData, self).save(*args, **kwargs) Calculations.save() class Calculations(FreshData): three = models.IntegerField() I've got a valueerror pointing out "self.one" and "self.two" as without value. I keep the idea in witch my design is wrong and django has a simpler way to store related data.

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  • Adding fields to a proxied class in Clojure

    - by mikera
    I'm using "proxy" to extend various Swing classes in a Clojure GUI application, generally with code that looks something like: (def ^JPanel mypanel (proxy [JPanel] [] (paintComponent [#^Graphics g] (.drawImage g background-image 0 0 nil)))) This works well but I can't figure out how to add additional fields to the newly extended class, for example making the background-image a field that could be subsequently updated. This would be pretty easy and common practice in Java. Is there a good way to do this in Clojure? Or is there another preferred method to achieve the same effect?

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  • What are good uses for Python3's "Function Annotations"

    - by agscala
    Function Annotations: PEP-3107 I ran across a snippet of code demonstrating Python3's function annotations. The concept is simple but I can't think of why these were implemented in Python3 or any good uses for them. Perhaps SO can enlighten me? How it works: def foo(a: 'x', b: 5 + 6, c: list) -> max(2, 9): ... function body ... Everything following the colon after an argument is an 'annotation', and the information following the -> is an annotation for the function's return value. foo.func_annotations would return a dictionary: {'a': 'x', 'b': 11, 'c': list, 'return': 9} What's the significance of having this available?

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  • inheriting scope from a has_many relationship

    - by hb922
    I am using ruby on rails 3.1 and have 2 models, an event and a group. Each event has_many groups, but has to have at least one "master" group, where the column :is_master = true Class Group < ActiveRecord::Base has_many :users belongs_to :event scope :master, where (:is_master => true) end Class Event< ActiveRecord::Base has_many :groups def master_group groups.master end end I want to be able to default all properties of the master group to the event, so for example, event.users.count should be the same as event.master_group.users.count. Is there any way to do something like this? Can I do a has_many :through = master_group? Am I approaching this the wrong way? Thanks!

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  • How to make form validation in Django dynamic?

    - by Oli
    I'm trying to make a form that handles the checking of a domain: the form should fail based on a variable that was set earlier in another form. Basically, when a user wants to create a new domain, this form should fail if the entered domain exists. When a user wants to move a domain, this form should fail if the entered domain doesn't exist. I've tried making it dynamic overload the initbut couldn't see a way to get my passed variabele to the clean function. I've read that this dynamic validation can be accomplished using a factory method, but maybe someone can help me on my way with this? Here's a simplified version of the form so far: #OrderFormStep1 presents the user with a choice: create or move domain class OrderFormStep2(forms.Form): domain = forms.CharField() extension = forms.CharField() def clean(self): cleaned_data = self.cleaned_data domain = cleaned_data.get("domain") extension = cleaned_data.get("extension") if domain and extension: code = whoislookup(domain+extension); #Raise error based on result from OrderFormStep1 #raise forms.ValidationError('error, domain already exists') #raise forms.ValidationError('error, domain does not exist') return cleaned_data

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  • Using Python, How to copy files in 'temporary internet files' folder in Windows

    - by pythBegin
    I am using this code to find files recursively in a folder , with size greater than 50000 bytes. def listall(parent): lis=[] for root, dirs, files in os.walk(parent): for name in files: if os.path.getsize(os.path.join(root,name))>500000: lis.append(os.path.join(root,name)) return lis This is working fine. But when I used this on 'temporary internet files' folder in windows, am getting this error. Traceback (most recent call last): File "<pyshell#4>", line 1, in <module> listall(a) File "<pyshell#2>", line 5, in listall if os.path.getsize(os.path.join(root,name))>500000: File "C:\Python26\lib\genericpath.py", line 49, in getsize return os.stat(filename).st_size WindowsError: [Error 123] The filename, directory name, or volume label syntax is incorrect: 'C:\\Documents and Settings\\khedarnatha\\Local Settings\\Temporary Internet Files\\Content.IE5\\EDS8C2V7\\??????+1[1].jpg' I think this is because windows gives names with special characters in this specific folder... Please help to sort out this issue.

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  • Hashing a python function to regenerate output when the function is modified

    - by Seth Johnson
    I have a python function that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_function(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_function from time to time, but I would like to avoid having it run again while it's unchanged. [time_consuming_function only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or ridiculous? Updated: based on the answers, it looks like what I want to do is to "memoize" time_consuming_function, except instead of (or in addition to) arguments passed into an invariant function, I want to account for a function that itself will change.

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  • Best way to parse XMPP-like XML streams?

    - by codethief
    I am working on a server application which receives data over a TCP socket in an XMPP-like XML format, i.e. every child of the <root> element essentially represents one separate request (stanza). The connection is closed as soon as </root> is received. I do know that I must use a stream parser like SAX, somehow. Though, for convenience, I'd prefer to have a tree-like interface to access each stanza's child elements. (The data sent with every request is not large so I think it makes sense to read each stanza as a whole.) What's the best way to realize that in Python (preferably v3)? This is the code I'd like to build it in. Feel free to point me in a totally different direction to solve this issue. import socketserver import settings class MyServer(socketserver.ThreadingMixIn, socketserver.TCPServer): pass class MyRequestHandler(socketserver.StreamRequestHandler): def handle(self): pass if __name__ == '__main__': server = MyServer((settings.host, settings.port), MyRequestHandler) server.serve_forever()

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  • pyschool is wrong ?

    - by geekkid
    I'm currently learning python and trying to do exercises at pyschools (if anyone knows what it is). Anyway, i have an exercise that asks me to do the following : Write a function percent(value, total) that takes in two numbers as arguments, and returns the percentage value as an integer. Here's my code: def percent(value, total): percent = value / total * 100 return int(percent) It works great in my Python Idle and it gives all the correct answers. however, when i run it in the pyschools website, it says that , for example , when the function is called with parameters 46 and 90 , the function returns 0. However, in my python idle , it correctly returns 51. What might be the problem ? Thank you very much for your help!

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  • JSON is not nested in rails view

    - by SeanGeneva
    I have a several models in a heirarchy, 1:many at each level. Each class is associated only with the class above it and the one below it, ie: L1 course, L2 unit, L3 unit layout, L4 layout fields, L5 table fields (not in code, but a sibling of layout fields) I am trying to build a JSON response of the entire hierarchy. def show @course = Course.find(params[:id]) respond_to do |format| format.html # show.html.erb format.json do @course = Course.find(params[:id]) @units = @course.units.all @unit_layouts = UnitLayout.where(:unit_id => @units) @layout_fields = LayoutField.where(:unit_layout_id => @unit_layouts) response = {:course => @course, :units => @units, :unit_layouts => @unit_layouts, :layout_fields => @layout_fields} respond_to do |format| format.json {render :json => response } end end end end The code is bring back the correct values, but the units, unit_layouts and layout_fields are all nested at the same level under course. I would like them to be nested inside their parent.

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  • Show a modal right after signup?

    - by user1494756
    When a user signup at my page I want them to be redirected to the root_path(this I have figured out how to do in the user controller). But then I want a modal to show in front of this page(and this should only happen the first time the user see this root/home page(like a flash message). Here is my create method in the user controller: def create @user = User.new(params[:user]) if @user.save sign_in @user redirect_to root_path else render 'new' end end The modal is placed in app/views/layouts/_modal.html.erb. Does anybody know how to make this happen? (Jepp, I am a newbie :)

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  • How do I check for Existence of a Record in GAE

    - by VDev
    I am trying to create a simple view in Django & GAE, which will check if the user has a profile entity and prints a different message for each case. I have the program below, but somehow GAE always seem to return a object. My program is below import datetime from django.http import HttpResponse, HttpResponseRedirect from google.appengine.api import users from google.appengine.ext import db from models import Profile import logging #from accounts.views import profile # Create your views here. def login_view(request): user = users.get_current_user() profile = db.GqlQuery("SELECT * FROM Profile WHERE account = :1", users.get_current_user()) logging.info(profile) logging.info(user) if profile: return HttpResponse("Congratulations Your profile is already created.") else: return HttpResponse("Sorry Your profile is NOT created.") My model object is Profile defined as follows: class Profile(db.Model): first_name = db.StringProperty() last_name = db.StringProperty() gender = db.StringProperty(choices=set(["Male", "Female"])) account = db.UserProperty(required = True) friends = db.ListProperty(item_type=users.User) last_login = db.DateTimeProperty(required=True) Thanks for the help.

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  • Basic Python: Exception raising and local variable scope / binding

    - by SuperJdynamite
    I have a basic "best practices" Python question. I see that there are already StackOverflow answers tangentially related to this question but they're mired in complicated examples or involve multiple factors. Given this code: #!/usr/bin/python def test_function(): try: a = str(5) raise b = str(6) except: print b test_function() what is the best way to avoid the inevitable "UnboundLocalError: local variable 'b' referenced before assignment" that I'm going to get in the exception handler? Does python have an elegant way to handle this? If not, what about an inelegant way? In a complicated function I'd prefer to avoid testing the existence of every local variable before I, for example, printed debug information about them.

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  • Model's method not being recognized when called

    - by Brian Roisentul
    I'm using ruby on rails 2.3.2 and also using the acts_as_taggable_on puglin. That generated me two db tables: tags and taggings. As I didn't need anything more from those, I didn't create a Tag model, for example. Now the project is more mature, I need to create some methods for tags, so I created a Tag model with some methods in it. The model looks something like this: class Tag < ActiveRecord::Base def self.get_parent parent = Tag.find(self.parent_id) return parent end end When I call it from a controller, it won't find the method. This is the code: tag = Tag.find(tag_id) the_parent = tag.get_parent This will throw an error saying: undefined method `get_parent' for #<Tag id: 13, name: "Historia", parent_id: 12> I don't know what's wrong. Any help will be appreciated.

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  • Permutations in python 2.5.2

    - by flpgdt
    Hi, I have a list of numbers for input, e.g. 671.00 1,636.00 436.00 9,224.00 and I want to generate all possible sums with a way to id it for output, e.g.: 671.00 + 1,636.00 = 2,307.00 671.00 + 436.00 = 1,107.00 671.00 + 9,224.00 = 9,224.00 671.00 + 1,636.00 + 436.00 = 2,743.00 ... and I would like to do it in Python My current constrains are: a) I'm just learning python now (that's part of the idea) b) I will have to use Python 2.5.2 (no intertools) I think I have found a piece of code that may help: def all_perms(str): if len(str) <=1: yield str else: for perm in all_perms(str[1:]): for i in range(len(perm)+1): #nb str[0:1] works in both string and list contexts yield perm[:i] + str[0:1] + perm[i:] ( from these guys ) But I'm not sure how to use it in my propose. Could someone trow some tips and pieces of code of help? cheers, f.

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  • How to access YAML sublevel item in a nested variable?

    - by Kleber S.
    Getting the error: You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.[] APP_CONFIG are loading fine. account_type = 'sample' allowed = APP_CONFIG['account']["#{account_type}"]['highlight'] Error points to 'allowed' variable line. The method that I currently trying to is: def self.allow_highlight?(account) account_type = Account.find(account).active_pack # returning a string - OK logger.debug account_type.class # checked on console - OK allowed = APP_CONFIG['account']["#{account_type}"]['highlight'] # Error line if total_account_highlight > allowed false else true end end Hope you understand. Any doubts, please ask me. Thanks!

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  • mysql select from multi tables problem

    - by moustafa
    this is the query SELECT members.memberID, members.salutation, members.firstName, members.middleName, members.lastName, members.suffix, members.company, addresses.address1, addresses.address2, addresses.city, addresses.state, addresses.postalCode, addresses.country, addresses.memberID, email.email, email.memberID, phonenumbers.phoneNumber, phonenumbers.memberId, subscriptions.year, subscriptions.memberID FROM members, addresses, email, phonenumbers, subscriptions WHERE subscriptions.year = '%s' AND subscriptions.memberID = members.memberID AND subscriptions.memberID = addresses.memberID AND subscriptions.memberID = email.memberID AND subscriptions.memberID = phonenumbers.memberID ORDER BY members.lastName, members.firstName, members.company LIMIT 0, 10 my problem is its a huge query so Im trying to limit it to so many at a time... its supposed to have over 5000 results... anyway the only limit that works is limit 0, 10 if you do anything else 5, 10 it doesnt work 0, 50 doesnt work... only 0, 10 works... and when I do 0, 10 the query returns blake firstName, middleName, lastName, and a few others... and when I do a print_r() on the $result it shows them blank as well and there is most def data in the database and there is also no typos for that...

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  • What is the most efficient functional version of the following imperative code?

    - by justin.r.s.
    I'm learning Scala and I want to know the best way of expressing this imperative pattern using Scala's functional programming capabilities. def f(l: List[Int]): Boolean = { for (e <- l) { if (test(e)) return true } } return false } The best I can come up with is along the lines of: l map { e => test(e) } contains true But this is less efficient since it calls test() on each element, whereas the imperative version stops on the first element that satisfies test(). Is there a more idiomatic functional programming technique I can use to the same effect? The imperative version seems awkward in Scala.

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