Float is generally an approximation, see [here][1] for some simple examples. You could get very nice results modifying your model to something like `DecimalField(max_digits=9, decimal_places=6)`, since decimals are very important in coordinates but using more than 6 is basically meaningless.

  [1]: https://docs.python.org/2/library/decimal.html#quick-start-tutorial


Use PointField to store lat long

    p = Point(85.3240, 27.7172,srid=4326)


Django: 1.X:

https://docs.djangoproject.com/en/1.11/ref/contrib/gis/model-api/#pointfield

Django: 2.X:

https://docs.djangoproject.com/en/2.2/ref/contrib/gis/model-api/#pointfield

Django: 3.X:
https://docs.djangoproject.com/en/3.0/ref/contrib/gis/model-api/#pointfield


The suggestion here to use `DecimalField(max_digits=9, decimal_places=6)` resulted in errors for me when trying to save locations from Google Maps.

If we assume that the most common use case is retrieving point locations from the Maps API, and a typical URL from Google Maps when right-clicking and selecting &quot;What&#39;s Here?&quot; yields something like:

`https://www.google.com/maps/place/37&#176;48&#39;52.3&quot;N+122&#176;17&#39;09.1&quot;W/@37.814532,-122.2880467,17z`

(random place)

So the longitude has 15 places before and after the decimal, which is why the accepted answer doesn&#39;t work. Since there&#39;s no reason to validate for &quot;as short as possible&quot; and db storage is cheap, I&#39;m using:

```longitude = models.DecimalField(
    max_digits=22,
    decimal_places=16)
```



I have been developing a site using babel-node and browserify with the babelify transform, to support ES6 syntax.

&lt;b&gt;I am just wondering, can I run this in production as&lt;/b&gt; `babel-node server` &lt;b&gt;rather than&lt;/b&gt; `node server` &lt;b&gt; What other options do I have to run ES6 in node?&lt;/b&gt;

Here are the commands I am running for build and start in development

    // npm run build
    browserify -t [babelify] client.js &gt; public/js/bundle.js&quot;,
    
    // npm start
    babel-node server.js&quot;

Here are my dev dependencies

    &quot;babel&quot;: &quot;^4.0.1&quot;,
    &quot;babelify&quot;: &quot;^5.0.3&quot;,
    &quot;browserify&quot;: &quot;^8.0.3&quot;

Is it okay to use babel-node in production

I&#39;m having some trouble creating CSS circles in react-native.  The following works in iPhone 6 Plus but in all the other iPhones, they become diamonds.

    circle: {
      height: 30,
      width: 30,
      borderRadius: 30,
    }

Now if I use PixelRatio on `borderRadius` it works in everything but iPhone 6 plus.  iPhone 6 plus renders it as boxes with rounded corners.

    circle: {
      height: 30,
      width: 30,
      borderRadius: 30 / PixelRatio.get(),
    }


Creating CSS circles in react-native

I want to store my users location using longitude and latitude, at the moment this comes from Google Maps, but I will be using GeoDango and some point to work out distances between to points also. 

However, my first confusion is which field in Django I should be using to store the longitude and latitude values? The information I&#39;m getting is conflicting. 


The official documentation uses a ``FloatField``
https://docs.djangoproject.com/en/dev/ref/contrib/gis/tutorial/#geographic-models

    lon = models.FloatField()
    lat = models.FloatField()

Where almost every answer on stackoverflow shows a ``DecimalField``

    long = models.DecimalField(max_digits=8, decimal_places=3)
    lat = models.DecimalField(max_digits=8, decimal_places=3)

So what should I be using?



Which Model Field to use in Django to store longitude and latitude values?

I want to store my users location using longitude and latitude, at the moment this comes from Google Maps, but I will be using GeoDango and some point to work out distances between to points also.
However, my first confusion is which field in Django I should be using to store the longitude and latitude values? The information I'm getting is conflicting.
The official documentation uses a <code>FloatField</code>
<a href="https://docs.djangoproject.com/en/dev/ref/contrib/gis/tutorial/#geographic-models" target="_blank" rel="noopener noreferrer">https://docs.djangoproject.com/en/dev/ref/contrib/gis/tutorial/#geographic-models</a>
<pre><code class="hljs language-ini">lon = models.FloatField()
lat = models.FloatField()
</code></pre>
Where almost every answer on stackoverflow shows a <code>DecimalField</code>
<pre><code class="hljs language-ini">long = models.DecimalField(max_digits=8, decimal_places=3)
lat = models.DecimalField(max_digits=8, decimal_places=3)
</code></pre>
So what should I be using?

How can I make [`@functools.lru_cache`][1] decorator ignore some of the function arguments with regard to caching key?

For example, I have a function that looks like this:

    def find_object(db_handle, query):
        # (omitted code)
        return result

If I apply `lru_cache` decorator just like that, `db_handle` will be included in the cache key. As a result, if I try to call the function with the same `query`, but different `db_handle`, it will be executed again, which I&#39;d like to avoid. I want `lru_cache` to consider `query` argument only.

  [1]: https://docs.python.org/3/library/functools.html#functools.lru_cache

Make @lru_cache ignore some of the function arguments

Consider simple Django models `Event` and `Participant`:

    class Event(models.Model):
        title = models.CharField(max_length=100)
    
    class Participant(models.Model):
        event = models.ForeignKey(Event, db_index=True)
        is_paid = models.BooleanField(default=False, db_index=True)
    
It&#39;s easy to annotate events query with total number of participants:

    events = Event.objects.all().annotate(participants=models.Count(&#39;participant&#39;))

**How to annotate with count of participants filtered by `is_paid=True`?**

I need to query **all events** regardless of number of participants, e.g. I don&#39;t need to filter by annotated result. If there are `0` participants, that&#39;s ok, I just need `0` in annotated value.

The [example from documentation](https://docs.djangoproject.com/en/1.8/topics/db/aggregation/#order-of-annotate-and-filter-clauses) doesn&#39;t work here, because it excludes objects from query instead of annotating them with `0`.

**Update.** Django 1.8 has new [conditional expressions feature](https://docs.djangoproject.com/en/1.8/ref/models/conditional-expressions/), so now we can do like this:

    events = Event.objects.all().annotate(paid_participants=models.Sum(
        models.Case(
            models.When(participant__is_paid=True, then=1),
            default=0,
            output_field=models.IntegerField()
        )))


**Update 2.** Django 2.0 has new [Conditional aggregation](https://docs.djangoproject.com/en/2.0/ref/models/conditional-expressions/#conditional-aggregation) feature, see [the accepted answer](https://stackoverflow.com/a/48649024/326406) below.

**Update 3.** For Django 3.x please [check this answer below](https://stackoverflow.com/a/70234015/326406).

How to filter objects for count annotation in Django?

I am trying to convert working Python 2.7 code into Python 3 code and I am receiving a type error from the urllib request module.

I used the inbuilt 2to3 Python tool to convert the below working urllib and urllib2 Python 2.7 code:

    import urllib2
    import urllib
    
    url = &quot;https://www.customdomain.com&quot;
    d = dict(parameter1=&quot;value1&quot;, parameter2=&quot;value2&quot;)
    
    req = urllib2.Request(url, data=urllib.urlencode(d))
    f = urllib2.urlopen(req)
    resp = f.read()


The output from the 2to3 module was the below Python 3 code:


    import urllib.request, urllib.error, urllib.parse
    
    url = &quot;https://www.customdomain.com&quot;
    d = dict(parameter1=&quot;value1&quot;, parameter2=&quot;value2&quot;)
    
    req = urllib.request.Request(url, data=urllib.parse.urlencode(d))
    f = urllib.request.urlopen(req)
    resp = f.read()





 
When the Python 3 code is run the following error is produced:

    ---------------------------------------------------------------------------
    TypeError                                 Traceback (most recent call last)
    &lt;ipython-input-56-206954140899&gt; in &lt;module&gt;()
          5 
          6 req = urllib.request.Request(url, data=urllib.parse.urlencode(d))
    ----&gt; 7 f = urllib.request.urlopen(req)
          8 resp = f.read()
    
    C:\Users\Admin\Anaconda3\lib\urllib\request.py in urlopen(url, data, timeout, cafile, capath, cadefault, context)
        159     else:
        160         opener = _opener
    --&gt; 161     return opener.open(url, data, timeout)
        162 
        163 def install_opener(opener):
    
    C:\Users\Admin\Anaconda3\lib\urllib\request.py in open(self, fullurl, data, timeout)
        459         for processor in self.process_request.get(protocol, []):
        460             meth = getattr(processor, meth_name)
    --&gt; 461             req = meth(req)
        462 
        463         response = self._open(req, data)
    
    C:\Users\Admin\Anaconda3\lib\urllib\request.py in do_request_(self, request)
       1110                 msg = &quot;POST data should be bytes or an iterable of bytes. &quot; \
       1111                       &quot;It cannot be of type str.&quot;
    -&gt; 1112                 raise TypeError(msg)
       1113             if not request.has_header(&#39;Content-type&#39;):
       1114                 request.add_unredirected_header(
    
    TypeError: POST data should be bytes or an iterable of bytes. It cannot be of type str.



I have also read two other tickets ([ticket1][1] and [ticket2][2]) which mentioned encoding the date. 

When I changed the line `f = urllib.request.urlopen(req)` to `f = urllib.request.urlopen(req.encode(&#39;utf-8&#39;))` I received the following error: `AttributeError: &#39;Request&#39; object has no attribute &#39;encode&#39;`

I am stuck as to how to make the Python 3 code work. Could you please help me?


  [1]: https://stackoverflow.com/questions/28850421/post-data-should-be-bytes-or-an-iterable-of-bytes-it-cannot-be-of-type-str
  [2]: https://stackoverflow.com/questions/5440485/typeerror-post-data-should-be-bytes-or-an-iterable-of-bytes-it-cannot-be-str

Python 3 urllib produces TypeError: POST data should be bytes or an iterable of bytes. It cannot be of type str

I have a simple python code as follows:


    import numpy as np
    import matplotlib.pyplot as plt

    &quot;&quot;&quot;
    Here are the solutions and the plot.
    &quot;&quot;&quot;
    
    # Create the axis and plot.
    plt.axis([0, 10, 0, 10])
    axis_x = range(1, 11)
    grd = [1.1, 2.1, 3.1, 4.1, 5.1, 6.1, 7.1, 8.1, 9.1, 10.1]
    grd2 = [1.2, 2.2, 3.2, 4.2, 5.2, 6.2, 7.2, 8.2, 9.2, 10.2]
    plt.plot(axis_x, grd, &#39;-g&#39;, label=&#39;BR1&#39;)
    plt.plot(axis_x, grd2, &#39;-b&#39;, label=&#39;BR2&#39;)
    plt.legend(loc=&#39;upper left&#39;)
    plt.grid()
    plt.show()
    
    # Save the results vector to a text file.
    np.savetxt(&#39;test.out&#39;, (grd, grd2))
    
    # Save the figure as &#39;.eps&#39; file.
    plt.savefig(&#39;expl.pdf&#39;, format=&#39;pdf&#39;, dpi=1200)

When I open the output files `expl.pdf` and/or `test.out` I find them blank and nothing in there. Why?

Thanks.

Why is my plt.savefig is not working?

I have an event loop that runs some co-routines as part of a command line tool. The user may interrupt the tool with the usual &lt;kbd&gt;Ctrl&lt;/kbd&gt; + &lt;kbd&gt;C&lt;/kbd&gt;, at which point I want to clean up properly after the interrupted event loop.

Here&#39;s what I tried.

&lt;!-- language: python --&gt;

    import asyncio
    
    
    @asyncio.coroutine
    def shleepy_time(seconds):
        print(&quot;Shleeping for {s} seconds...&quot;.format(s=seconds))
        yield from asyncio.sleep(seconds)
    
    
    if __name__ == &#39;__main__&#39;:
        loop = asyncio.get_event_loop()
    
        # Side note: Apparently, async() will be deprecated in 3.4.4.
        # See: https://docs.python.org/3.4/library/asyncio-task.html#asyncio.async
        tasks = [
            asyncio.async(shleepy_time(seconds=5)),
            asyncio.async(shleepy_time(seconds=10))
        ]
    
        try:
            loop.run_until_complete(asyncio.gather(*tasks))
        except KeyboardInterrupt as e:
            print(&quot;Caught keyboard interrupt. Canceling tasks...&quot;)
    
            # This doesn&#39;t seem to be the correct solution.
            for t in tasks:
                t.cancel()
        finally:
            loop.close()

Running this and hitting &lt;kbd&gt;Ctrl&lt;/kbd&gt; + &lt;kbd&gt;C&lt;/kbd&gt; yields:

    $ python3 asyncio-keyboardinterrupt-example.py 
    Shleeping for 5 seconds...
    Shleeping for 10 seconds...
    ^CCaught keyboard interrupt. Canceling tasks...
    Task was destroyed but it is pending!
    task: &lt;Task pending coro=&lt;shleepy_time() running at asyncio-keyboardinterrupt-example.py:7&gt; wait_for=&lt;Future cancelled&gt; cb=[gather.&lt;locals&gt;._done_callback(1)() at /usr/local/Cellar/python3/3.4.3/Frameworks/Python.framework/Versions/3.4/lib/python3.4/asyncio/tasks.py:587]&gt;
    Task was destroyed but it is pending!
    task: &lt;Task pending coro=&lt;shleepy_time() running at asyncio-keyboardinterrupt-example.py:7&gt; wait_for=&lt;Future cancelled&gt; cb=[gather.&lt;locals&gt;._done_callback(0)() at /usr/local/Cellar/python3/3.4.3/Frameworks/Python.framework/Versions/3.4/lib/python3.4/asyncio/tasks.py:587]&gt;

Clearly, I didn&#39;t clean up correctly. I thought perhaps calling `cancel()` on the tasks would be the way to do it.

What&#39;s the correct way to clean up after an interrupted event loop?

What&#39;s the correct way to clean up after an interrupted event loop?

I know that there are answers regarding Django Rest Framework, but I couldn&#39;t find a solution to my problem.

I have an application which has authentication and some functionality.
I added a new app to it, which uses Django Rest Framework. I want to use the library only in this app. Also I want to make POST request, and I always receive this response:

    {
        &quot;detail&quot;: &quot;CSRF Failed: CSRF token missing or incorrect.&quot;
    }

I have the following code:

    # urls.py
    from django.conf.urls import patterns, url
    
    
    urlpatterns = patterns(
        &#39;api.views&#39;,
        url(r&#39;^object/$&#39;, views.Object.as_view()),
    )
    
    # views.py
    from rest_framework.views import APIView
    from rest_framework.response import Response
    from django.views.decorators.csrf import csrf_exempt
    
    
    class Object(APIView):
    
        @csrf_exempt
        def post(self, request, format=None):
            return Response({&#39;received data&#39;: request.data})

I want add the API without affecting the current application.
So my questions is how can I disable CSRF only for this app ?

Django Rest Framework remove csrf

I am trying to decide whether I should use Django&#39;s `Client` or `RequestFactory` to test my views.

I am creating my server using DjangoRESTFramework and it&#39;s really simple, so far:

    class SimpleModelList(generics.ListCreateAPIView):
        &quot;&quot;&quot;
        Retrieve list of all route_areas or create a new one.
        &quot;&quot;&quot;
        queryset = SimpleModel.objects.all()
        serializer_class = SimpleModelSerializer
        filter_backends = (IsOwnerFilterBackend,)
        
        def perform_create(self, serializer):
            serializer.save(owner=self.request.user)

What are the differences between testing with Django&#39;s `Client` and `RequestFactory` and which approach is more suited for testing a REST server (if there is any difference besides liking one better)?

Should I create tests with both so as to provide a better coverage for my system?

Django test RequestFactory vs Client

I have a case where the values for a serializer field depend on the identity of the currently logged in user.  I have seen how to add the user to the context when initializing a serializer, but I am not sure how to do this when using a ViewSet, as you only supply the serializer class and not the actual serializer instance.

Basically I would like to know how to go from:

    class myModelViewSet(ModelViewSet):
       queryset = myModel.objects.all()
       permission_classes = [DjangoModelPermissions]
       serializer_class = myModelSerializer

to:

    class myModelSerializer(serializers.ModelSerializer):
        uploaded_by = serializers.SerializerMethodField()
        special_field = serializers.SerializerMethodField()
    
        class Meta:
            model = myModel
    
        def get_special_field(self, obj):
            if self.context[&#39;request&#39;].user.has_perm(&#39;something.add_something&#39;):
               return something

Sorry if it wasn&#39;t clear, from the DOCs:
[Adding Extra Context][1] 
Which says to do 

    serializer = AccountSerializer(account, context={&#39;request&#39;: request})
    serializer.data

But I am not sure how to do that automatically from the viewset, as I only can change the serializer class, and not the serializer instance itself.

  [1]: http://www.django-rest-framework.org/api-guide/serializers/#including-extra-context

Pass request context to serializer from Viewset in Django Rest Framework

&lt;!-- language-all: python --&gt;

Let&#39;s say I have a `Product` model with products in a storefront, and a `ProductImages` table with images of the product, which can have zero or more images. Here&#39;s a simplified example:

    class Product(models.Model):
      product_name = models.CharField(max_length=255)
      # ...
    
    class ProductImage(models.Model):
      product = models.ForeignKey(Product, related_name=&#39;images&#39;)
      image_file = models.CharField(max_length=255)
      # ...
  
When displaying search results for products, I want to prioritize products which have images associated with them. I can easily get the number of images:

    from django.db.models import Count
    Product.objects.annotate(image_count=Count(&#39;images&#39;))

But that&#39;s not actually what I want. I&#39;d like to annotate it with a boolean field, `have_images`, indicating whether the product has one or more images, so that I can sort by that:

    Product.objects.annotate(have_images=(?????)).order_by(&#39;-have_images&#39;, &#39;product_name&#39;)

How can I do that? Thanks!

Content Type	Original Author	Original Content on Stackoverflow
Question	Prometheus	View Question on Stackoverflow
Solution 1 - Python	mccc	View Answer on Stackoverflow
Solution 2 - Python	Amulya Acharya	View Answer on Stackoverflow
Solution 3 - Python	shacker	View Answer on Stackoverflow

Which Model Field to use in Django to store longitude and latitude values?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

Creating CSS circles in react-native

Is it okay to use babel-node in production

Attributions