Try `default=None`. There is no `NULL` in **python**.

If you specify null=True on the model field then the value will be stored as NULL in the database if the user does not provide a value.

- `blank=True`
   allows you to input nothing (i.e `&quot;&quot;`, `None`) and keep it empty.
- `null=True`
   means the database row is allowed to be `NULL`.
- `default=None`
   sets the field to `None` if no other value is given.

Is it possible to program Android apps in Clojure?
Can anybody suggest a good tutorial or book, if it is possible?

Clojure on Android

I&#39;m mucking about with node.js and have discovered two ways of reading a file and sending it down the wire, once I&#39;ve established that it exists and have sent the proper MIME type with writeHead:

    // read the entire file into memory and then spit it out

    fs.readFile(filename, function(err, data){
      if (err) throw err;
      response.write(data, &#39;utf8&#39;);
      response.end();
    });

    // read and pass the file as a stream of chunks

    fs.createReadStream(filename, {
      &#39;flags&#39;: &#39;r&#39;,
      &#39;encoding&#39;: &#39;binary&#39;,
      &#39;mode&#39;: 0666,
      &#39;bufferSize&#39;: 4 * 1024
    }).addListener( &quot;data&quot;, function(chunk) {
      response.write(chunk, &#39;binary&#39;);
    }).addListener( &quot;close&quot;,function() {
      response.end();
    });

Am I correct in assuming that fs.createReadStream might provide a better user experience if the file in question was something large, like a video? It feels like it might be less block-ish; is this true?  Are there other pros, cons, caveats, or gotchas I need to know?

What are the pros and cons of fs.createReadStream vs fs.readFile in node.js?

I need to have my Django application allow me to have a default value of NULL set for a certain model field. I&#39;ve looked over the *null*, *blank*, and *default* parameters, but it&#39;s not very clear what combination of the three I need to use to get the desired effect. I&#39;ve tried setting `default=NULL` but it threw an error. If I specify `blank=True, null=True` and no default, will it just default back to NULL come runtime?

Django Model Field Default to Null

I need to have my Django application allow me to have a default value of NULL set for a certain model field. I've looked over the null, blank, and default parameters, but it's not very clear what combination of the three I need to use to get the desired effect. I've tried setting <code>default=NULL</code> but it threw an error. If I specify <code>blank=True, null=True</code> and no default, will it just default back to NULL come runtime?

I have a piece of code in Python that seems to cause an error probabilistically because it is accessing a server and sometimes that server has a 500 internal server error. I want to keep trying until I do not get the error. My solution was:

    while True:
    	try:
    	    #code with possible error
    	except:
             continue
        else:
             #the rest of the code
             break
This seems like a hack to me. Is there a more Pythonic way to do this?

In Python try until no error

Why is `cls` sometimes used instead of `self` as an argument in Python classes?

For example:

    class Person:
        def __init__(self, firstname, lastname):
            self.firstname = firstname
            self.lastname = lastname

        @classmethod
        def from_fullname(cls, fullname):
            cls.firstname, cls.lastname = fullname.split(&#39; &#39;, 1)

Difference between &#39;cls&#39; and &#39;self&#39; in Python classes?

I&#39;m trying to auto-generate basic documentation for my codebase using Sphinx. However, I&#39;m having difficulty instructing Sphinx to recursively scan my files.

I have a Python codebase with a folder structure like:

    &lt;workspace&gt;
    └── src
        └── mypackage
            ├── __init__.py
            │   
            ├── subpackageA
            │   ├── __init__.py
            │   ├── submoduleA1
            │   └── submoduleA2
            │   
            └── subpackageB
                ├── __init__.py
                ├── submoduleB1
                └── submoduleB2

I ran sphinx-quickstart in `&lt;workspace&gt;`, so now my structure looks like:

    &lt;workspace&gt;
    ├── src
    │   └── mypackage
    │       ├── __init__.py
    │		│
    │       ├── subpackageA
    │       │   ├── __init__.py
    │       │   ├── submoduleA1
    │       │   └── submoduleA2
    │       │
    │		└── subpackageB
    │           ├── __init__.py
    │           ├── submoduleB1
    │           └── ubmoduleB2
    │
    ├── index.rst
    ├── _build
    ├── _static
    └── _templates  

I&#39;ve read the [quickstart tutorial](https://www.sphinx-doc.org/en/master/usage/quickstart.html), and although I&#39;m still trying to understand the docs, the way it&#39;s worded makes me concerned that Sphinx assumes I&#39;m going to manually create documentation files for every single module/class/function in my codebase.

However, I did notice the &quot;automodule&quot; statement, and I enabled autodoc during quickstart, so I&#39;m hoping most of the documentation can be automatically generated. I modified my conf.py to add my src folder to sys.path and then modified my index.rst to use automodule. So now my index.rst looks like:

    Contents:

    .. toctree::
       :maxdepth: 2

    Indices and tables
    ==================

    * :ref:`genindex`
    * :ref:`modindex`
    * :ref:`search`

    .. automodule:: alphabuyer
       :members:

I have dozens of classes and functions defined in the subpackages. Yet, when I run:

    sphinx-build -b html . ./_build

it reports:

    updating environment: 1 added, 0 changed, 0 removed

And this appears to have failed to import anything inside my package. Viewing the generated index.html shows nothing next to &quot;Contents:&quot;. The Index page only shows &quot;mypackage (module)&quot;, but clicking it shows it also has no contents.

How do you direct Sphinx to recursively parse a package and automatically generate documentation for every class/method/function it encounters, without having to manually list every class yourself?

Automatically Generating Documentation for All Python Package Contents

Can I get console input without echo in python?

Can i get console input without echo in python?

I want to change a couple of files at one time, __iff__ I can write to all of them. I&#39;m wondering if I somehow can combine the multiple open calls with the `with` statement:

    try:
      with open(&#39;a&#39;, &#39;w&#39;) as a and open(&#39;b&#39;, &#39;w&#39;) as b:
        do_something()
    except IOError as e:
      print &#39;Operation failed: %s&#39; % e.strerror

If that&#39;s not possible, what would an elegant solution to this problem look like?

How can I open multiple files using &quot;with open&quot; in Python?

I&#39;ve accumulated quite a few migrations using South (0.7) and Django (1.1.2) which are starting to consume quite a bit of time in my unit tests. I would like to reset the baseline and start a fresh set of migrations. I&#39;ve reviewed the &lt;a href=&quot;http://south.aeracode.org/docs/index.html&quot;&gt;South documentation&lt;/a&gt;, done the usual Google/Stackoverflow searching (e.g. &quot;django south (reset OR delete OR remove) migration history&quot;) and haven&#39;t found anything obvious.

One approach I&#39;ve contemplated would involve &quot;starting over&quot; by &quot;removing&quot; South or &quot;clearing&quot; the history manually (e.g. clear the db table, remove migration files from the migrations director) and just re-run,

&gt; ./manage.py schemamigration southtut --initial

So, if anyone has done this before and has some tips/suggestions they would be greatly appreciated.

What&#39;s the recommended approach to resetting migration history using Django South?

I&#39;m trying to find a way to cache the results of a query that won&#39;t change with frequency. For example, categories of products from an e-commerce (cellphones, TV, etc).
I&#39;m thinking of using the template fragment caching, but in this fragment, I will iterate over a list of these categories. This list is avaliable in any part of the site, so it&#39;s in my `base.html` file. Do I have always to send the list of categories when rendering the templates? Or is there a more dynamic way to do this, making the list always available in the template?

Caching query results in django

I tried to use PIL to do some JPEG work in my django app with PIL but I&#39;m getting this IOError.. not sure what to do.

    &quot;&quot;decoder jpeg not available&quot;&quot;

Am I missing the JPEG decoder from my server? If so, how do I fix it?


PIL /JPEG Library: &quot;decoder jpeg not available&quot;

I have a Django application that sends an email.  The production server has an email server but my local box does not.  I would like to be able to test sending of email locally.  Is there any way that I can have django not send it through the email server and just print out to a file or console?

Test sending email without email server

    def index(request):
        the_user = request.user

In Django, how do I know if it&#39;s a real user or not?  I tried:

`if the_user:`  but &quot;AnonymousUser&quot; is there even if no one logs in.  So, it always returns true and this doesn&#39;t work.

How do I check whether this user is anonymous or actually a user on my system?

I&#39;ve got a field in one model like:

    class Sample(models.Model):
        date = fields.DateField(auto_now=False)

Now, I need to filter the objects by a date range.

How do I filter all the objects that have a date between `1-Jan-2011` and `31-Jan-2011`?

How do I filter query objects by date range in Django?

    Foo.objects.get(pk=&quot;foo&quot;)
    &lt;Foo: test&gt;

In the database, I want to add another object which is a copy of the object above.

Suppose my table has one row. I want to insert the first row object into another row with a different primary key. How can I do that?


How do I clone a Django model instance object and save it to the database?

I need to change the `inline title` to something else other than the `verbose_name` of the class Meta in the model. Is there an attribute to achieve this?



How to set another Inline title in Django Admin?

I need to perform a django query that checks if a field contains all values within a list. The list will be of varying length

Example

    User.objects.filter(first_name__contains=[&#39;x&#39;,&#39;y&#39;,&#39;z&#39;])

Django: Query using contains each value in a list

Let&#39;s say I am in the save code. How can I obtain the model&#39;s name or the content type of the object, and use it?

    from django.db import models

    class Foo(models.Model):
        ...
        def save(self):
            I am here....I want to obtain the model_name or the content type of the object

This code works, but I have to know the model_name:

    import django.db.models
    from django.contrib.contenttypes.models import ContentType

    content_type = ContentType.objects.get(model=model_name)
    model = content_type.model_class()

Content Type	Original Author	Original Content on Stackoverflow
Question	SPoage	View Question on Stackoverflow
Solution 1 - Python	gruszczy	View Answer on Stackoverflow
Solution 2 - Python	Kevin	View Answer on Stackoverflow
Solution 3 - Python	Henning Lee	View Answer on Stackoverflow

Django Model Field Default to Null

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

What are the pros and cons of fs.createReadStream vs fs.readFile in node.js?

Clojure on Android

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