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  • Doing a count over a filter query efficiently in django

    - by apple_pie
    Hello, Django newbie here, I need to do a count over a certain filter in a django model. If I do it like so: my_model.objects.filter(...).count() I'm guessing it does the SQL query that retrieves all the rows and only afterwards does the count. To my knowledge it's much more efficient to do the count without retrieving those rows like so "SELECT COUNT(*) FROM ...". Is there a way to do so in django?

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  • How do I include the Django settings file?

    - by alex
    I have a .py file in a directory , which is inside the Django project folder. I have email settings in my settings.py, but this .py file does not import that file. How can I specify to Django that settings.py should be used , so that I can use EmailMessage class with the settings that are in my settings.py?

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  • Can Django be used for web services?

    - by alex
    My friend said, "Pylons is so much better for web services." My other friend said, "You can modify Django in a way to do exactly whatever you like." In Django, what is necessary to be modified (urls.py? models classes? settings?) in order to do "web services" with APIs and REST and versioning, etc etc.?

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  • How can I create a rules engine without using eval() or exec()?

    - by Angela
    I have a simple rules/conditions table in my database which is used to generate alerts for one of our systems. I want to create a rules engine or a domain specific language. A simple rule stored in this table would be..(omitting the relationships here) if temp > 40 send email Please note there would be many more such rules. A script runs once daily to evaluate these rules and perform the necessary actions. At the beginning, there was only one rule, so we had the script in place to only support that rule. However we now need to make it more scalable to support different conditions/rules. I have looked into rules engines , but I hope to achieve this in some simple pythonic way. At the moment, I have only come up with eval/exec and I know that is not the most recommended approach. So, what would be the best way to accomplish this?? ( The rules are stored as data in database so each object like "temperature", condition like "/=..etc" , value like "40,50..etc" and action like "email, sms, etc.." are stored in the database, i retrieve this to form the condition...if temp 50 send email, that was my idea to then use exec or eval on them to make it live code..but not sure if this is the right approach )

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  • I'm getting the following error ''expected an indented block'' Where is the failing code?

    - by user1833814
    import math def area(base, height): '''(number,number) -> number Return the area of a wirh given base and height. >>>area(10,40) 200.0 ''' return base * height / 2 def perimeter(side1, side2, side3): '''(number,number,number) -> number Return the perimeter of the triangle with sides of length side1,side2 and side3. >>>perimeter(3,4,5) 12 >>>perimeter(10.5,6,9.3) 25.8 ''' return (side1 + side2 + side3) def semiperimeter(side1, side2, side3): return perimeter(side1, side2, side3) / 2 def area_hero(side1, side2, side3): semi = semiperimeter(side1, side2, side3) area = math.sqrt((semi * (semi - side1) * (semi - side2) * (semi - side3)) return area

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  • Pygame single push event

    - by Miller92Time
    in Pygame i am trying to translate an image by 10% in each direction using each arrow key. right now the code i am using moves the image as long as the key is pushed down, what I want is for it to move only once regardless if the key is still pushed down or not. if event.type == KEYDOWN: if (event.key == K_RIGHT): DISPLAYSURF.fill((255,255,255)) #Clears the screen translation_x(100) draw(1) if (event.key == K_LEFT): DISPLAYSURF.fill((255,255,255)) #Clears the screen translation_x(-100) draw(2) if (event.key == K_UP): DISPLAYSURF.fill((255,255,255)) #Clears the screen translation_y(100) draw(3) if (event.key == K_DOWN): DISPLAYSURF.fill((255,255,255)) #Clears the screen translation_y(-100) draw(4) is there a simpler way of implementing this besides using time.sleep

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  • How do I dynamically import a module in App Engine?

    - by Scott Ferguson
    I'm trying to dynamically load a class from a specific module (called 'commands') and the code runs totally cool on my local setup running from a local Django server. This bombs out though when I deploy to Google App Engine. I've tried adding the commands module's parent module to the import as well with no avail (on either setup in that case). Here's the code: mod = __import__('commands.%s' % command, globals(), locals(), [command]) return getattr(mod, command) App Engine just throws an ImportError whenever it hits this. And the clarify, it doesn't bomb out on the commands module. If I have a command like 'commands.cat' it can't find 'cat'.

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  • Programmatic binding of accelerators in wxPython

    - by Inductiveload
    I am trying to programmatically create and bind a table of accelerators in wxPython in a loop so that I don't need to worry about getting and assigning new IDs to each accelerators (and with a view to inhaling the handler list from some external resource, rather than hard-coding them). I also pass in some arguments to the handler via a lambda since a lot of my handlers will be the same but with different parameters (move, zoom, etc). The class is subclassed from wx.Frame and setup_accelerators() is called during initialisation. def setup_accelerators(self): bindings = [ (wx.ACCEL_CTRL, wx.WXK_UP, self.on_move, 'up'), (wx.ACCEL_CTRL, wx.WXK_DOWN, self.on_move, 'down'), (wx.ACCEL_CTRL, wx.WXK_LEFT, self.on_move, 'left'), (wx.ACCEL_CTRL, wx.WXK_RIGHT, self.on_move, 'right'), ] accelEntries = [] for binding in bindings: eventId = wx.NewId() accelEntries.append( (binding[0], binding[1], eventId) ) self.Bind(wx.EVT_MENU, lambda event: binding[2](event, binding[3]), id=eventId) accelTable = wx.AcceleratorTable(accelEntries) self.SetAcceleratorTable(accelTable) def on_move(self, e, direction): print direction However, this appears to bind all the accelerators to the last entry, so that Ctrl+Up prints "right", as do all the other three. How to correctly bind multiple handlers in this way?

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  • rename keys in a dictionary

    - by user366660
    i want to rename the keys of a dictionary are which are ints, and i need them to be ints with leading zeros's so that they sort correctly. for example my keys are like: '1','101','11' and i need them to be: '001','101','011' this is what im doing now, but i know there is a better way tmpDict = {} for oldKey in aDict: tmpDict['%04d'%int(oldKey)] = aDict[oldKey] newDict = tmpDict

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  • How can I update only certain fields in a Django model form?

    - by J. Frankenstein
    I have a model form that I use to update a model. class Turtle(models.Model): name = models.CharField(max_length=50, blank=False) description = models.TextField(blank=True) class TurtleForm(forms.ModelForm): class Meta: model = Turtle Sometimes I don't need to update the entire model, but only want to update one of the fields. So when I POST the form only has information for the description. When I do that the model never saves because it thinks that the name is being blanked out while my intent is that the name not change and just be used from the model. turtle_form = TurtleForm(request.POST, instance=object) if turtle_form.is_valid(): turtle_form.save() Is there any way to make this happen? Thanks!

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  • Django shell command to change a value in json data

    - by crozzfire
    I am a django newbie and i was playing around in django's manage.py shell. Here is something i am trying in the shell: >>> data [{'primary_program': False, 'id': 3684}, {'primary_program': True, 'id': 3685}] >>> data[0] {'primary_program': False, 'id': 3684} >>> data[1] {'primary_program': True, 'id': 3685} >>> data[0].values() [False, 3684] >>> data[1].values() [True, 3685] >>> How should i give a command here to update the value of primary_program in data[1] to False and keep the rest of the json the same?

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  • read the dictionary value from array

    - by ben martin
    CALORIES = \ { 'Beef' : 200, \ 'Chicken' : 140, \ } class Food(): __slots__ = ( 'cal' # Calories ) def mkFood( name ): """Create and return a newly initialized Food item""" result = Food() result.cal = calorie in dict(CALORIES[1]) return result Is that a proper way to the value of the target item in Calories? Like getting 200, 140, such like that. result.cal = calorie in dict(CALORIES[1])

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  • Take data from an XML file and put it into a MySQL database

    - by Aidan
    Hi Guys, I'm looking to construct a script that would go through an XML file. Would find specific tags in it, put them in a table and fill the table with specific tags within them. I'm using MySQL 5.1 so loadXML isn't an option and I think that ExtractData() method wont be much use either.. but I don't really know. What would be the best way to go about this?

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  • SQLAlchemy: an efficient/better select by primary keys?

    - by hadrien
    Yet another newbie question.. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I have a list of users identifiers, I fetch them from db with: user_ids = [1, 2, 3, 4, 5] users = Session.query(User).filter(User.id.in_(user_ids)).all() I dislike using in_ because I think I learned it has bad performance on indexed fields (is that true/false?). Anyway, is there a better way doing that query? Thanks!

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  • Saving a Django form to a csv file

    - by Oli
    I have a Django form that is working fine. I'd like to save the data it submits to a CSV file. Is there a "best practice" way to do this? I need to include blank fields in the CSV file where the user has not filled in a "required=False" field

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  • Partially flattening a list

    - by alj
    This is probably a really silly question but, given the example code at the bottom, how would I get a single list that retain the tuples? (I've looked at the itertools but it flattens everything) What I currently get is: ('id', 20, 'integer') ('companyname', 50, 'text') [('focus', 30, 'text'), ('fiesta', 30, 'text'), ('mondeo', 30, 'text'), ('puma', 30, 'text')] ('contact', 50, 'text') ('email', 50, 'text') what I would like is a single level list like: ('id', 20, 'integer') ('companyname', 50, 'text') ('focus', 30, 'text') ('fiesta', 30, 'text') ('mondeo', 30, 'text') ('puma', 30, 'text') ('contact', 50, 'text') ('email', 50, 'text') def getproducts(): temp_list=[] product_list=['focus','fiesta','mondeo','puma'] #usually this would come from a db for p in product_list: temp_list.append((p,30,'text')) return temp_list def createlist(): column_title_list = ( ("id",20,"integer"), ("companyname",50,"text"), getproducts(), ("contact",50,"text"), ("email",50,"text"), ) return column_title_list for item in createlist(): print item Thanks ALJ

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  • Wait until a webpage finished loading to load the next one in a list

    - by envy
    Hi! I'm using PyQT webView to visit some webpages I have stored on a dictionary the code is something like this: def loadLink(self, url): manager = QNetworkAccessManager() request = QNetworkRequest(QUrl(url)) self.ui.webView.load(QUrl(visitar)) def readUnreadLinks(self): print "Links to read: " + str(len(self.unreadLinks)) for link in self.unreadLinks: print "link-> " + str(link) self.loadLink(link) the problem is it doesn't wait until finished loading the web page and starts loading the next one. I want to load a webpage, wait until it finished loading and then load the next one. Thanks, this is driving me crazy :)

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  • Yet another list comprehension question

    - by relima
    I had this: if Setting["Language"] == "en": f.m_radioBox3.SetSelection(0) elif Setting["Language"] == "pt": f.m_radioBox3.SetSelection(1) elif Setting["Language"] == "fr": f.m_radioBox3.SetSelection(2) elif Setting["Language"] == "es": f.m_radioBox3.SetSelection(3) Then I did this: Linguas = ["en","pt","fr","es"] a = 0 for i in Linguas: if i == Setting["Language"]: f.m_radioBox3.SetSelection(a) a += 1 Is it possible to further simplify this and make it into a one-liner?

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  • Setting `axes.linewidth` without changing the `rcParams` global dict

    - by mlvljr
    So, it seems one cannot do the following (it raises an error, since axes does not have a set_linewidth method): axes_style = {'linewidth':5} axes_rect = [0.1, 0.1, 0.9, 0.9] axes(axes_rect, **axes_style) and has to use the following old trick instead: rcParams['axes.linewidth'] = 5 # set the value globally ... # some code rcdefaults() # restore [global] defaults Is there an easy / clean way (may be one can set x- and y- axes parameters individually, etc)? P.S. If no, why?

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  • What does this `_time_independent_equlas` mean?

    - by Satoru.Logic
    In the tornado.web module there is a function called _time_independent_equals: def _time_independent_equals(a, b): if len(a) != len(b): return False result = 0 for x, y in zip(a, b): result |= ord(x) ^ ord(y) return result == 0 It is used to compare secure cookie signatures, and thus the name. But regarding the implementation of this function, is it just a complex way to say a==b?

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  • how to use cherrpy built in data storage

    - by user291071
    Ok I have been reading the cherrypy documents for sometime and have not found a simple example yet. Let say I have a simple hello world site, how do I store data? Lets say I want to store a = 1, and b =2 to a dictionary using cherrypy. The config files are confusing as hell. Anyone have very simple example of storing values from a simple site in cherrypy?

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