Django community: RSS
This page, updated regularly, aggregates Community blog posts from the Django community.
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Using Python weasyprint generate HTML to PDF in django
In most of the web development projects you might want to automate file generation, like for example placeorder confirmation receipts, payment receipts, that can be based on a template you are using. The library we will be using is Weasyprint. WeasyPrint is to combine multiple pieces of information into an HTML template and then converting it to a PDF document. The supported version are Python 2.7, 3.3+ WeasyPrint has lot of dependencies, So this can be install it with pip. pip install Weasyprint Once you have installed WeasyPrint, you should have a weasyprint executable. This can be as simple: weasyprint --version This will Print WeasyPrint's version number you have installed. weasyprint <Your_Website_URL> <Your_path_to_save_this_PDF> Eg: weasyprint http://samplewebsite.com ./test.pdf Here i have converted "http://samplewebsite.com" site to an test.pdf. Let we write sample PDF Generation: from weasyprint import HTML, CSS HTML('http://samplewebsite.com/').write_pdf('/localdirectory/test.pdf', stylesheets=[CSS(string='body { font-size: 10px }')]) This will also converts the page in to PDF, Here the change is we are writting custom stylesheet(CSS) for the body to change the font size using the "string" argument. You can also pass the CSS File, This can be done using: from django.conf import settings … -
Transcoding with AWS- part four
As I have my transcoder up and running now it's time to let user know that their uploaded files were transcoded. To this occasion I will use AWS SNS service which allows me to send notification about completion of transcode job. Table of Contents: Setting up AWS SNS to work with AWS Transcoder Receiving notifications from SNS service in Django Other blog posts in this series Setting up AWS SNS to work with AWS Transcoder After logging to AWS console and selecting SNS I have to create a topic: Topic is endpoint for other application in AWS to send their notifications. For my case I have to change it in AWS Transcoder pipeline settings: Last thing I have to do was to create subscription for topic created above. They are a lot of types of subscription that you can find in SNS settings but I will be using HTTP request. Receiving notifications from SNS service in Django The flow of application will look like this: User upload a file File is sent to S3 Transcode job is fired after uploading form view After transcode completion AWS transcoder sends SNS notification This notification is taken by SNS subscription and send to … -
Transcoding with AWS- part four
As I have my transcoder up and running now it's time to let user know that their uploaded files were transcoded. To this occasion I will use AWS SNS service which allows me to send notification about completion of transcode job. Table of Contents: Setting up AWS SNS to work … -
New year, new Python: Python 3.6
Python 3.6 was released in the tail end of 2016. Read on for a few highlights from this release. New module: secrets Python 3.6 introduces a new module in the standard library called secrets. While the random module has long existed to provide us with pseudo-random numbers suitable for applications like modeling and simulation, these were not "cryptographically random" and not suitable for use in cryptography. secrets fills this gap, providing a cryptographically strong method to, for instance, create a new, random password or a secure token. -
Which components should I use in production?
This is the last in a series of posts about whether you should choose Ubuntu or Windows, Gunicorn or uWSGI, MySQL or PostgreSQL, and Apache or nginx. I bring it altogether. The image illustrates the components I propose for a start. […]The post Which components should I use in production? appeared first on Django deployment. -
5 Reasons I don't think you shold use the django admin
Have you ever needed to quickly modify data or look it up. But while the task is simple the entire process of changing one value frustrates you? Well, this is very common to me, bad UX is annoying. I quite often have to either lookup, or edit, two disparate, yet related pieces of data, and sometimes it is an exercise in frustration. An all to common occurrence is I just needed to check the edit history of a "Company" our database. This is a simple process, go to the admin find the Company model, do a search and you have your answer. Except, it isn't that easy in reality. Lets run through what really happened. I went to "http://superawesomesite.com/admin/" and logged in. I then looked at how my model options extended well below the fold of my browser so I had to scroll. No problem I'll just hit "ctrl+f" and search for it. WTF!!! where is my company model? I then proceed to scroll down and finally find it only to remember it was pluralized. If I had searched for "Companies" I would have been good to go, grrrrr. I click into and see the list of companies available to … -
Event sourcing in Django
Django comes with "batteries included" to make CRUD (create, read, update, delete) operations easy. It's nice that the CR part (create and read) of CRUD is so easy, but have you ever paused to think about the UD part (update and delete)? Let's look at delete. All you need to do is this: ReallyImportantModel.objects.get(id=32).delete() # gone from the database forever Just one line, and your data is gone forever. It can be done accidentally. Or you can be do it deliberately, only to later realise that your old data is valuable too. Now what about updating? Updating is deleting in disguise. When you update, you're deleting the old data and replacing it with something new. It's still deletion. important = ReallyImportantModel.object.get(id=32) important.update(data={'new_data': 'This is new data'}) # OLD DATA GONE FOREVER Okay, but why do we care? Let's say we want to know the state of ReallyImportantModel 6 months ago. Oh that's right, you've deleted it, so you can't get it back. Well, that's not exactly true -- you can recreate your data from backups (if you don't backup your database, stop reading right now and fix that immediately). But that's clumsy. So by only storing the current state of … -
Event sourcing in Django
Django comes with "batteries included" to make CRUD (create, read, update, delete) operations easy. It's nice that the CR part (create and read) of CRUD is so easy, but have you ever paused to think about the UD part (update and delete)? Let's look at delete. All you need to do is this: ReallyImportantModel.objects.get(id=32).delete() # gone from the database forever Just one line, and your data is gone forever. It can be done accidentally. Or you can be do it deliberately, only to later realise that your old data is valuable too. Now what about updating? Updating is deleting in disguise. When you update, you're deleting the old data and replacing it with something new. It's still deletion. important = ReallyImportantModel.object.get(id=32) important.update(data={'new_data': 'This is new data'}) # OLD DATA GONE FOREVER Okay, but why do we care? Let's say we want to know the state of ReallyImportantModel 6 months ago. Oh that's right, you've deleted it, so you can't get it back. Well, that's not exactly true -- you can recreate your data from backups (if you don't backup your database, stop reading right now and fix that immediately). But that's clumsy. So by only storing the current state of … -
Django - Database access optimization
Django Queryset is generally lazy in nature. It will not hit the database until it evaluates the query results. Example: queryset = User.objects.all() # It won't hit the database print (queryset) # Now, ORM turns the query into raw sql and fetches results from the database 1.Caching and QuerySets Generally Django stores the query results in the catche when it fetches the results for the first time. Example: Get all users first names list and emails list from the database. first_names_list = [ user.first_name for user in User.objects.all()] emails_list = [ user.email for user in User.objects.all()] above code hits the database twice. To avoid the extra request to the database we can use the Django's database cache in the following way. users_list = User.objects.all() # No database activity first_names_list = [user.first_name for user in users_list] # Hits the database and stores the results in the cache emails_list = [user.email for user in users_list] # uses the results from the cache. other way is users_list = User.objects.all() db = dict(users_list.values_list("first_name", "email")) first_names_list, emails_list = db.keys(), db.values() Note: Querysets are not cached if query is not evaluated. Eaxmple: If you want to take a subset/part of the query results queryset = Users.objects.all() first_five = queryset[:5] # Hits … -
Webfaction LetsEncrypt Django
Why HTTPS First things first. I do not work for Google nor I have any (social, financial, ethical etc) benefits from this gigantic company. But let be honest. If you are not ranked hign enough in Google's search results, your optimism about your website success is slowly betake to collapse. I think everybody that owns a website, wants his "e-property" to be shown amongst the first results in Google. Of course, you might say, that the search keywords added in the search bar are very important too, but that is not to be discussed here. So, you have a website (maybe you have build it too) and your domain is i.e http://www.ilovewhatido.com/. Then you read this blog post by Google and got terrified about your ranking position. Thinking "Oh man, I have to change the http protocol to https. How painful will this be?" or "how much do I have to pay (monthly or yearly) in order to do that?" or "if I switch to https, will my web app behave the same as it was with http?". Lets give answers to these questions: "Oh man, I have to change the http protocol to https. How painful will this be?" … -
Django custom sitemap (updated 2018)
UPDATE Sep 2018: The old post regarding the template tag had some bugs. As of 2018, I fixed it and now this post is updated and works only for Python 3.6+. So you have done the following: Used your favorite Web Framework (Django) to build your website. Made enough tests to verify that everything is working flawlessly. Translated your whole website in each language and (of course) each page has its translated version. Used i18n_patterns function to prefix your urls with the language code. Hosted your website somewhere and... asked yourself why Google does not index your translated pages of your website. Introduction This excellent article from Google states that there are 2 kinds of "translated" websites: multilingual and multi-regional. You can have none, one of them or both, depending on your needs. Let's assume that you have build a multiregional website: A multilingual website is any website that offers content in more than one language. Examples of multilingual websites might include a Canadian business with an English and a French version of its site, or a blog on Latin American soccer available in both Spanish and Portuguese. It also states that: Keep the content for each language on separate … -
Django Administration: Inlines for Inlines
The default Django model administration comes with a concept of inlines. If you have a one-to-many relationship, you can edit the parent and its children in the same form. However, you are limited in a way that you cannot have inlines under inlines at nested one-to-many relations. For example, you can't show models Painter, Picture, and Review in the same form if one painter may have drawn multiple pictures and each picture may have several reviews. In this article I would like to share a workaround allowing you to quickly access the inlines of an inline model. The idea is that for every inline you can provide a HTML link leading to the separate form where you can edit the related model and its own relations. It's as simple as that. For example, in the form of Painter model, you have the instances of Picture listed with specific links "Edit this Picture separately": When such a link is clicked, the administrator goes to the form of the Picture model which shows the instances of Review model listed underneath: Let's have a look, how to implement this. First of all, I will create a gallery app and define the three models … -
Django is Boring, or Why Tech Startups (Should) Use Django
I recently attended Django Under The Hood in Amsterdam, an annual gathering of Django core team members and developers from around the world. A common theme discussed at the conference this year is that “Django is boring.” While it’s not the first time this has been discussed, it still struck me as odd. Upon further reflection, however, I see Django’s “boringness” as a huge asset to the community and potential adopters of the framework. -
Using Fanout.io in Django
Earlier this year we started using Fanout.io in Air Mozilla to enhance the experience for users awaiting content updates. Here I hope to flesh out its details a bit to inspire others to deploy a similar solution. What It Is First of all, Fanout.io is basically a service that handles your WebSockets. You put in some of Fanout's JavaScript into your site that handles a persistent WebSocket connection between your site and Fanout.io. And to push messages to your user you basically send them to Fanout.io from the server and they "forward" it to the WebSocket. The HTML page looks like this: <html> <body> <h1>Web Page</h1> <!-- replace the FANOUT_REALM_ID with the ID you get in the Fanout.io admin page --> <script src="https://{{ FANOUT_REALM_ID }}.fanoutcdn.com/bayeux/static/faye-browser-1.1.2-fanout1-min.js" ></script> <script src="fanout.js"></script> </body> </html> And the fanout.js script looks like this: window.onload = function() { // replace the FANOUT_REALM_ID with the ID you get in the Fanout.io admin page var client = new Faye.Client('https://{{ FANOUT_REALM_ID }}.fanoutcdn.com/bayeux') client.subscribe('/mycomments', function(data) { console.log('Incoming updated data from the server:', data); }) }; And in server it looks something like this: from django.conf import settings import fanout fanout.realm = settings.FANOUT_REALM_ID fanout.key = settings.FANOUT_REALM_KEY def post_comment(request): """A django view function … -
Transcoding with AWS- part two
As I have static and media files integrated with AWS now it's time to transcode them. In this post, I will write a short example of how to integrate AWS ElasticTranscoder with Django application. Table of Contents: Basic terms Code Other blog posts in this series Basic terms ElasticTranscoder allows you to transcode files from your S3 bucket to various formats. To set this service up first you have to create a pipeline. What pipeline is? Basically, it's a workflow- how your transcoder should work. You can create a different pipeline for long content and different for short one. In my application I created the following pipeline: As I have my pipeline configured next step is to create jobs. Jobs are tasks for a transcoder that say which file I want to transcode, to what format or codec I want to do this: PresetID is user created or already existing configuration that defines the format of transcoder output: is it mp4 or maybe flac? What resolution should video files have? All of this is set up in present. As we know basic terms used in AWS Elastic Transcoder let's jump into the code. Code AWS has very good python API … -
Transcoding with AWS- part two
As I have static and media files integrated with AWS now it's time to transcode them. In this post, I will write a short example of how to integrate AWS ElasticTranscoder with Django application. Table of Contents: Basic terms Code Other blog posts in this series Basic terms ElasticTranscoder allows … -
Django, custom SMTP server for logging
One of my client uses google apps, so I use that account to send out mails with Django, which works just fine. However, google silently drops all error mails to the admins, for whatever reason you can't debug and will never hear anything about anyway. As those mails only go to the dev team it doesn't really matter which mailserver is used, so I decided to write my own email handler. To use it add it to the LOGGING settings like you would the normal AdminEmailHandler and add the necessary settings to your configuration. Raw from django.conf import settings from django.core.mail import get_connection from django.utils.log import AdminEmailHandler class MyAdminEmailHandler(AdminEmailHandler): """ Use a custom handler because gmail sucks... """ def connection(self): return get_connection( host=settings.LOG_EMAIL_HOST, port=settings.LOG_EMAIL_PORT, username=settings.LOG_EMAIL_USER, password=settings.LOG_EMAIL_PASSWORD, use_tls=settings.LOG_EMAIL_USE_TLS, ) -
Django, custom SMTP server for logging
One of my client uses google apps, so I use that account to send out mails with Django, which works just fine. However, google silently drops all error mails to the admins, for whatever reason you can't debug and will never hear anything about anyway. As those mails only go to the dev team it doesn't really matter which mailserver is used, so I decided to write my own email handler. To use it add it to the LOGGING settings like you would the normal AdminEmailHandler and add the necessary settings to your configuration. Raw from django.conf import settings from django.core.mail import get_connection from django.utils.log import AdminEmailHandler class MyAdminEmailHandler(AdminEmailHandler): """ Use a custom handler because gmail sucks... """ def connection(self): return get_connection( host=settings.LOG_EMAIL_HOST, port=settings.LOG_EMAIL_PORT, username=settings.LOG_EMAIL_USER, password=settings.LOG_EMAIL_PASSWORD, use_tls=settings.LOG_EMAIL_USE_TLS, ) -
A Quick Look at the Kubernetes Python Client
For those of you that don't know there is a new Python API client in the kubernetes-incubator project: client-python. There has been some high quality Python clients like pykube, but client-python can serve as the official Python client. ## The Structure of the Client client-python is a client that is mostly generated based on the swagger spec (UI). While pykube has the benefit of being totally idiomatic, client-python can support practically all of the endpoints and react quickly to changes in the API. client-python supports Python 3 and is currently tested against Python 3.4. ## Usin[...] -
How to Create Group By Queries With Django ORM
This tutorial is about how to implement SQL-like group by queries using the Django ORM. It’s a fairly common operation, specially for those who are familiar with SQL. The Django ORM is actually an abstraction layer, that let us play with the database as it was object-oriented but in the end it’s just a relational database and all the operations are translated into SQL statements. Most of the work can be done retrieving the raw data from the database, and playing with it in the Python side, grouping the data in dictionaries, iterating through it, making sums, averages and what not. But the database is a very powerful tool and do much more than simply storing the data, and often you can do the work much faster directly in the database. Generally speaking, when you start doing group by queries, you are no longer interested in each model instances (or in a table row) details, but you want extract new information from your dataset, based on some common aspects shared between the model instances. Let’s have a look in an example: class Country(models.Model): name = models.CharField(max_length=30) class City(models.Model): name = models.CharField(max_length=30) country = models.ForeignKey(Country) population = models.PositiveIntegerField() And the raw … -
Transcoding with AWS- part one
Nowadays moving everything to the cloud becomes more and more popular. A lot of software companies move their technology stack to such infrastructure. One of the biggest players in this field is Amazon Web Services - AWS. That's why I decided decided to adapt existing code from my previous project and move transcoding to write blog posts about that. In this series I process to cloud. Table of Contents: Overview of series Moving static and media files to AWS Overview of series I decided to adapt code from my previous blog series about celery and rabbit-mq. I did that because code from this django application actually transcodes mp3 files to other formats. This series will be divided into these parts: Moving static and media files to AWS Transcoding files inside AWS transcoder Notifying user that transcode is complete User downloads transcoded file Moving static and media files to AWS AWS transcoder operates only on files that are inside S3 bucket so first I need to change how these files are served in django. Let's say that I already had my account on AWS. Next step is to generate specific account using IAM. While creating a user I want to give … -
Transcoding with AWS- part one
Nowadays moving everything to the cloud becomes more and more popular. A lot of software companies move their technology stack to such infrastructure. One of the biggest players in this field is Amazon Web Services - AWS. That's why I decided decided to adapt existing code from my previous project and … -
Birthday retrospective
So, recently Evennia celebrated its ten-year anniversary. That is, it was on Nov 20, 2006, Greg Taylor made the first repo commit to what would eventually become the Evennia of today. Greg has said that Evennia started out as a "weird experiment" of building a MUD/MUX using Django. The strange name he got from a cheesy NPC in the Guild Wars MMORPG and Greg's first post to the mailing list also echoes the experimental intention of the codebase. The merger with Twisted came pretty early too, replacing the early asyncore hack he used and immediately seeing a massive speedup. Evennia got attention from the MUD community - clearly a Python-based MUD system sounded attractive.When I first joined the project I had been looking at doing something MUD-like in Python for a good while. I had looked over the various existing Python code bases at the time and found them all to be either abandoned or very limited. I had a few week's stunt working with pymoo before asking myself why I was going through the trouble of parsing a custom script language ... in Python ... Why not use Python throughout? This is when I came upon Evennia. I started … -
Optimizing the construction of Django QuerySets
Django’s ORM is normally fast enough as-is, but if you’ve ever profiled a high traffic view with a fairly complicated query, you might have found that constructing QuerySet can take a noticeable portion of your request time. For example, I once found a query on the front page of the site I was working on that took 1ms to construct and 1ms for the database to answer. With a performance budget of 100ms, that was 1% gone on computing the exactly same SQL. Thankfully we don’t need to instantly drop down to raw SQL to optimize such cases, as Django’s QuerySet API naturally lends itself to caching the intermediate objects. Since each operation on a QuerySet returns a new object with the change applied, they’re always lazy as to executing the SQL, and operations can (normally) be chained in any order, you can build the non-specific part of your QuerySet up as a cached object and then apply final, specific filtering required at request time. Just a note before we dive in: this should be one of the least reached for tools in your optimization toolbox - normally it’s enough to fix the basics such as avoiding N+1 queries with … -
How to reset migrations in Django 1.7 - 1.8 - 1.9 and above
Migrations help you propagate models changes to your database schema,they are particularly helpful in the situation when you need to change your database structure and you don't want or you can't drop a database table and recreate it or when you have a production database with tables which has millions of rows .Any developer has experienced situations where he has to change the structure of an existing table such as adding,deleting or renaming a field.In some cases droping the table and recreate it solve the problem and release the developer from the headache related to and resulted by the process but just imagine a scenario where your application is already in production with millions of database rows ,droping your old tables is not a choice.You can't even dear to think about it so migrations are here to present you a more acceptable and professional solution. Simply migrations lets you change your database schema while keeping your data. How to get started with migrations ? Getting started with migrations is easy especially with the latest versions of Django,starting with Django 1.7 .In fact from Django 1.7 migrations become obligatory since they are integrated within your django workflow. To work with migrations …
