https://www.chenshaowen.com/en/tags/python/Recent content in Python on Shaowen Chen's WebsiteHugo -- gohugo.ioen©2016 - {year}, All Rights Reserved.Thu, 28 Mar 2024 00:00:00 +0000weeklyhttps://www.chenshaowen.com/en/blog/conda-install-and-use.htmlThu, 28 Mar 2024 00:00:00 +0000Thu, 28 Mar 2024 00:00:00 +0000https://www.chenshaowen.com/en/blog/conda-install-and-use.html1. Installing conda 1 2 3 wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh bash Miniconda3-latest-Linux-x86_64.sh rm -rf Miniconda3-latest-Linux-x86_64.sh However, Miniconda cannot be used for free at large-scale commercial deployments, so you can use Miniforge as a drop-in alternative. 1 2 wget "https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-$(uname)-$(uname -m).sh" bash Miniforge3-$(uname)-$(uname -m).sh 2. Changing the default configuration 2.1 Initializing the Shell Without initialization, activating an environment reports CondaError: Run 'conda init' before 'conda activate'.微信公众号CondaPythonAIEnvironmentOperationshttps://www.chenshaowen.com/en/blog/usage-of-transformers-lib.htmlTue, 22 Aug 2023 00:00:00 +0000Tue, 22 Aug 2023 00:00:00 +0000https://www.chenshaowen.com/en/blog/usage-of-transformers-lib.htmltransformers is a Python library developed by Hugging Face for using and training pretrained Transformer models in natural language processing (NLP) tasks. It provides many powerful tools and features that make working with text data and building NLP models much easier. The library is widely used across a variety of微信公众号TransformerAILLMNLPPythonhttps://www.chenshaowen.com/en/blog/what-is-functional-programming.htmlWed, 02 Sep 2020 00:00:00 +0000Wed, 02 Sep 2020 00:00:00 +0000https://www.chenshaowen.com/en/blog/what-is-functional-programming.html1. What a Programming Paradigm Is A programming paradigm is a class of typical programming conventions. On one hand, it provides engineers with a way to model entities, linking the physical world to code; on the other hand, it provides engineers with a way of thinking about code and programs.微信公众号Functional ProgrammingGoProgramming ParadigmPythonWhat Ishttps://www.chenshaowen.com/en/blog/database-query-optimization-of-django-performance.htmlWed, 20 Mar 2019 00:00:00 +0000Wed, 20 Mar 2019 00:00:00 +0000https://www.chenshaowen.com/en/blog/database-query-optimization-of-django-performance.htmlThis article mainly offers optimization advice on Django fields and queries, and also introduces a performance analysis tool called Django-silk. I hope it helps you develop high-performance Django projects. 1. DBA’s Advice 1.1 Table Field Design Avoid null values; null values are hard to optimize queries around and take up extra index space Prefer INT over BIGINT, and describe fields as accurately as possible Use enums or integers instead of string types Use TIMESTAMP instead of DATETIME Do not put more than 20 fields in a single table Store IPs as integers 1.微信公众号DatabaseOptimizationPerformanceDjangoPythonR&Dhttps://www.chenshaowen.com/en/blog/mock-of-pytest.htmlSun, 27 Jan 2019 00:00:00 +0000Sun, 27 Jan 2019 00:00:00 +0000https://www.chenshaowen.com/en/blog/mock-of-pytest.html1. Why We Need Mock When writing unit tests, the function under test is sometimes not a self-contained executable unit. It depends on external resources, such as the return value of another function or a value in a row of a database. To shield the test from interference from external微信公众号TestingPythonPytestLearninghttps://www.chenshaowen.com/en/blog/101-of-pytest.htmlSat, 29 Dec 2018 00:00:00 +0000Sat, 29 Dec 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/101-of-pytest.htmlThe Pytest framework is simple to use, rich in plugins, and powerful, and it is widely used for Python automated testing. This article introduces some basic concepts and usage of Pytest. 1. How It Runs Step one, Pytest reads its configuration from the command line or a file. Step two,微信公众号TestingPythonPytestR&DLearningAutomated TestingUnit TestingBest Practiceshttps://www.chenshaowen.com/en/blog/api-of-viewset-and-serializer-in-rest-framework.htmlTue, 20 Nov 2018 00:00:00 +0000Tue, 20 Nov 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/api-of-viewset-and-serializer-in-rest-framework.html1. Serializer 1.1 Data Validation When deserializing data, the validity of the data needs to be checked. At this point you can call is_valid() for validation, and if a validation error occurs, you can get the error message from the .errors attribute. For example: 1 2 3 4 serializer.is_valid() # False serializer.微信公众号DjangoPythonAPIInterfaceR&Dhttps://www.chenshaowen.com/en/blog/viewset-and-serializer-in-rest-framework.htmlSun, 18 Nov 2018 00:00:00 +0000Sun, 18 Nov 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/viewset-and-serializer-in-rest-framework.html1. View Class in Django First, recall how Django handles a request. After receiving a request, Django creates a handler of type WSGIHandler, and the handler controls the entire processing flow. So how are the request URL and the View associated with each other? Django first loads the URLconf according to the ROOT_URLCONF setting, then matches the URLpatterns in the URLconf one by one in order, stopping as soon as a match is found.微信公众号DjangoPythonAPIFrameworkInterfaceR&Dhttps://www.chenshaowen.com/en/blog/django-full-stack-optimization-guide.htmlThu, 15 Nov 2018 00:00:00 +0000Thu, 15 Nov 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/django-full-stack-optimization-guide.htmlAs the data volume exploded, the system responded very slowly. We carried out a series of optimizations on the application, and the system’s response time improved by an order of magnitude. Overall, optimizations in file compression and faster network access gave a noticeable boost to frontend performance, while optimizations in stored procedures, caching, and logic code gave a noticeable boost to backend performance.微信公众号DjangoPythonOptimizationFrontendBackendGuideR&Dhttps://www.chenshaowen.com/en/blog/solving-the-problem-of-celery-processe-large-file-failure.htmlWed, 24 Oct 2018 00:00:00 +0000Wed, 24 Oct 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/solving-the-problem-of-celery-processe-large-file-failure.html1. A Small Requirement We run into small requirements all the time, but they are not always simple to implement. Here is a simple file upload requirement, broken into the following steps: The user uploads a large file on the page The large file is temporarily stored in the internal微信公众号CeleryPythonDjangoFailureTroubleshootingLarge FilesR&Dhttps://www.chenshaowen.com/en/blog/git-and-development-environment-setup.htmlFri, 19 Oct 2018 00:00:00 +0000Fri, 19 Oct 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/git-and-development-environment-setup.htmlCompiled from the “Development Tips” series, gathering practices around Git collaboration and development environment setup. 1. warning: LF will be replaced by CRLF Windows, Linux, and Mac are inconsistent in how they mark line endings in files. Windows uses CRLF as the terminator, while Linux and Mac use LF. Git微信公众号GitPythonWindowsR&DEnvironmenthttps://www.chenshaowen.com/en/blog/python-and-django-development-practices.htmlFri, 19 Oct 2018 00:00:00 +0000Fri, 19 Oct 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/python-and-django-development-practices.htmlCompiled from the “Development Tips” series, collecting common problems and solutions in Python and Django development. 1. Sorting Python Iterables Iterable objects fall into 3 main categories: All sequence types, such as list, str, and tuple Some non-sequence types, such as dict and file Objects that contain an __iter__() or微信公众号PythonDjangoR&DLearningBackendhttps://www.chenshaowen.com/en/blog/how-to-use-django-signal-decoupling-module.htmlFri, 12 Oct 2018 00:00:00 +0000Fri, 12 Oct 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/how-to-use-django-signal-decoupling-module.htmlRecently I was responsible for developing a backend-heavy application. The data flow in this application is complex, and the processing logic has piled up in a redundant mess. The project’s tech stack is Django + Vuejs. The frontend is bundled with Webpack, managed in modules, and mainly displays data. The backend involves many modules, many processing rules, and many data tables, so every time I had to modify an earlier feature I spent a lot of time reviewing the code.微信公众号DjangoPythonDesignDecouplingR&Dhttps://www.chenshaowen.com/en/blog/how-to-package-a-docker-image-of-robot-framework.htmlTue, 18 Sep 2018 00:00:00 +0000Tue, 18 Sep 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/how-to-package-a-docker-image-of-robot-framework.htmlTo make it easier for CI to integrate UI automation tests, the Robot Framework runtime needs to be packaged as a Docker image. This post covers the configuration and scripts involved in the packaging process. 1. Packaging Directory Structure 1 2 3 4 5 6 tree . ├──微信公众号DockerRobotFrameworkPythonTestingCICDOperationshttps://www.chenshaowen.com/en/blog/senior-of-robot-framework-2.htmlThu, 16 Aug 2018 00:00:00 +0000Thu, 16 Aug 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/senior-of-robot-framework-2.htmlSettings Table The settings table in Robot Framework mainly serves two purposes. For a detailed explanation, see here. Import test, resource, and variable files. Define metadata. In the Setting table: 1 2 3 4 5 Library 引入库 Resource 引入资源文件 Variables 引入变微信公众号RobotFrameworkPythonTestingAutomationDevOpshttps://www.chenshaowen.com/en/blog/senior-of-robot-framework-1.htmlWed, 15 Aug 2018 00:00:00 +0000Wed, 15 Aug 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/senior-of-robot-framework-1.htmlpybot Command Run all test cases 1 pybot . Run a certain test suite 1 pybot testsuite.txt Run a test case in a certain test suite 1 pybot --test case_name testsuit.txt Output the test results to a fixed path 1 pybot --ouputdir your_ouput_dir testsuit.txt Run test cases that contain a微信公众号RobotFrameworkPythonTestingAutomationDevOpshttps://www.chenshaowen.com/en/blog/how-to-create-gitlab-label-using-python-gitlab.htmlSun, 05 Aug 2018 10:00:00 +0000Sun, 05 Aug 2018 10:00:00 +0000https://www.chenshaowen.com/en/blog/how-to-create-gitlab-label-using-python-gitlab.htmlUsing GitLab issues for project management is a very Dev-friendly thing. Entering issues, opening Merge Requests, creating milestones — these all advance dynamically during development. But creating a pile of Labels for every new project is a headache. This article is mainly about solving that problem. 1. GitLab Label Before微信公众号GitLabPythonProject ManagementDevOpsR&Dhttps://www.chenshaowen.com/en/blog/basic-of-robot-framework.htmlTue, 24 Jul 2018 00:00:00 +0000Tue, 24 Jul 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/basic-of-robot-framework.htmlThis post mainly introduces some basic concepts of Robot Framework and how to write a test case. 1. Basic Elements 1.1 Keywords Robot Framework keywords are similar to functions. They are divided into system keywords and user-defined keywords. System keywords, imported by loading a Library User keywords, imported by loading微信公众号PythonTestingRobotFrameworkDevOpsLearningAutomated TestingR&DCICDhttps://www.chenshaowen.com/en/blog/how-to-secure-get-request-in-django.htmlTue, 26 Jun 2018 00:00:00 +0000Tue, 26 Jun 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/how-to-secure-get-request-in-django.htmlIn Django, request holds all the information for a single request. Backend processing logic frequently needs information from request. For example, the DRF framework may want to be able to obtain request at any time, or pass some parameters globally. There are third-party Django apps with tools that can satisfy微信公众号DjangoPythonR&DTipsLearningDRFThread Safetyhttps://www.chenshaowen.com/en/blog/dictionary-and-list-structure-in-python2.htmlMon, 12 Mar 2018 11:22:55 +0000Mon, 12 Mar 2018 11:22:55 +0000https://www.chenshaowen.com/en/blog/dictionary-and-list-structure-in-python2.html1. Why Dictionary Lookups Are Faster Than List Lookups First, take a look at the following piece of code. 1 2 3 4 5 6 7 8 9 10 11 12 13 from time import time t = time() data = [chr(i) for i in range(97, 123)] # data =微信公众号PythonSource CodeLearningR&Dhttps://www.chenshaowen.com/en/blog/python2-source-of-pyc.htmlFri, 09 Mar 2018 00:00:00 +0000Fri, 09 Mar 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/python2-source-of-pyc.htmlThis article uses the Python 2.7.8 source code as an example. 1. Common File Formats in Python py file A Python source code file, which can be modified with a text editor. pyc file The bytecode file generated after Python source code is compiled. pyw file When a pyc file is executed, a console window appears; when a pyw file is executed, it does not.微信公众号PythonSource CodeCompilationLearningR&Dhttps://www.chenshaowen.com/en/blog/how-to-build-a-pypi-server-using-devpi.htmlSun, 04 Mar 2018 00:00:00 +0000Sun, 04 Mar 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/how-to-build-a-pypi-server-using-devpi.htmlWhen you install Python packages with pip, it looks up the corresponding package on the https://pypi.python.org/simple/ index by default, then downloads and installs it. But in an intranet environment, or when you need to publish some private packages to designated users, you have to build your own PyPI Server. This post mainly records the process of building a PyPI Server index with the devpi tool, along with some commonly used commands.微信公众号PythondevpiToolsOperationsLearningPyPIPrivate IndexPackage ManagementIntranethttps://www.chenshaowen.com/en/blog/django-model-and-er-diagram.htmlFri, 02 Mar 2018 00:00:00 +0000Fri, 02 Mar 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/django-model-and-er-diagram.htmlAs requirements are gradually confirmed, the system’s DB model is gradually confirmed as well. Sometimes you use a tool like MySQL Workbench to draw an E-R diagram and then generate MySQL database tables, and at that point you need to reverse-generate Django Models; other times you write the Django Models directly, but then you need to look at the E-R diagram.微信公众号DjangoPythonDatabaseDesignModelR&Dhttps://www.chenshaowen.com/en/blog/development-specification-1-of-django.htmlSat, 27 Jan 2018 00:00:00 +0000Sat, 27 Jan 2018 00:00:00 +0000https://www.chenshaowen.com/en/blog/development-specification-1-of-django.htmlThis article mainly lays out a few things to watch out for during Django development. A consistent coding style and sound design principles help a project’s development and maintenance, and are worth developers studying and discussing continuously. 1. Encoding Declaration When the Python interpreter executes code, it needs to be微信公众号DjangoPythonConventionsR&DLearningBest PracticesCode StyleArchitecturehttps://www.chenshaowen.com/en/blog/process-and-thread-in-python.htmlSat, 06 Jan 2018 11:22:55 +0000Sat, 06 Jan 2018 11:22:55 +0000https://www.chenshaowen.com/en/blog/process-and-thread-in-python.html1. Processes A process is an instance of a running program, and it is the most basic unit by which the kernel allocates resources. A process has its own independent heap and stack, its own address space, and its own resource handles. Processes are scheduled by the OS, the scheduling微信公众号PythonConcurrencyProcessesThreadsCoroutinesR&DLearninghttps://www.chenshaowen.com/en/blog/class-function-method-of-python.htmlFri, 29 Dec 2017 00:00:00 +0000Fri, 29 Dec 2017 00:00:00 +0000https://www.chenshaowen.com/en/blog/class-function-method-of-python.html1. Function Methods A function is an organized, reusable snippet of code used to implement a single or related piece of functionality. Functions improve an application’s modularity and the reuse rate of code. Python provides many built-in functions, such as print() and str(). At the same time, Python also allows微信公众号PythonConventionsFunctionsR&Dhttps://www.chenshaowen.com/en/blog/interactive-notebook-jupyter.htmlMon, 25 Dec 2017 17:22:45 +0000Mon, 25 Dec 2017 17:22:45 +0000https://www.chenshaowen.com/en/blog/interactive-notebook-jupyter.html1. Introduction Jupyter Notebook (formerly IPython notebook) is an interactive notebook that supports running more than 40 programming languages. Jupyter Notebook is in fact a web application that lets you create and share program documents, with support for live code, mathematical equations, visualizations, and Markdown. Its uses include data cleaning微信公众号ToolsPythonNotesJupyterLearningR&DData AnalysisMachine LearningVisualizationhttps://www.chenshaowen.com/en/blog/message-queue-about-rabbitmq.htmlSat, 23 Dec 2017 20:51:22 +0000Sat, 23 Dec 2017 20:51:22 +0000https://www.chenshaowen.com/en/blog/message-queue-about-rabbitmq.html1. Where a Message Queue Fits 1.1 Asynchronous Processing Use case: after a user registers, a registration email and a registration SMS must be sent. With the synchronous approach, system performance (concurrency, throughput, response time) hits a bottleneck. 1.2 Application Decoupling Use case: after a user places an order, the微信公众号RabbitMQMiddlewareCeleryPythonMessageQueuehttps://www.chenshaowen.com/en/blog/error-code-design-and-unified-processing-in-django.htmlMon, 30 Oct 2017 21:50:33 +0000Mon, 30 Oct 2017 21:50:33 +0000https://www.chenshaowen.com/en/blog/error-code-design-and-unified-processing-in-django.htmlI currently use Django for SaaS development, and I develop and maintain several SaaS applications at the same time. Many SaaS applications have agreed-upon error codes, some used to handle login state, others to mark business logic status. For a feature that is so strongly shared across projects, it is微信公众号DjangoPythonError CodesMiddlewareR&DLearningAPIBest Practiceshttps://www.chenshaowen.com/en/blog/how-to-learn-a-new-programming-language-taking-python-as-an-example.htmlFri, 13 Oct 2017 23:00:06 +0000Fri, 13 Oct 2017 23:00:06 +0000https://www.chenshaowen.com/en/blog/how-to-learn-a-new-programming-language-taking-python-as-an-example.html1. Understand the Background of the New Language ABC was a teaching language designed specifically for non-professional programmers, but because it was closed, it did not succeed. During Christmas 1989, Guido van Rossum developed a new script interpreter and named it Python, as a kind of successor to the ABC微信公众号PythonLearningProgrammingR&Dhttps://www.chenshaowen.com/en/blog/build-django-development-environment-using-vagrant.htmlMon, 25 Sep 2017 21:56:05 +0000Mon, 25 Sep 2017 21:56:05 +0000https://www.chenshaowen.com/en/blog/build-django-development-environment-using-vagrant.htmlDocker solves the problem of environment isolation on the same machine and improves the efficiency of operations and deployment. Vagrant gives developers a unified, near-fully-isolated environment for development and testing. This article mainly discusses how to build a Django development environment with Vagrant. Versions: VirtualBox 5.0, Vagrant 1.8. 1. Basic微信公众号DjangoPythonVagrantToolsDevelopmentR&DOperationshttps://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-6.htmlSun, 24 Sep 2017 18:03:22 +0000Sun, 24 Sep 2017 18:03:22 +0000https://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-6.html1. Directory Structure The django-devops-uwsgi directory holds the image build files that package uWSGI and Django. It installs the necessary packages such as uWSGI, pip, and virtualenv into the image. When a container is created from the image, the start.sh script runs: it creates the Python virtual runtime environment, installs the dependency packages from Django’s requirements.微信公众号DockerDjangoPythonServicesToolsR&DOperationshttps://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-5.htmlSun, 24 Sep 2017 14:34:35 +0000Sun, 24 Sep 2017 14:34:35 +0000https://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-5.html1. Directory Structure 1 2 3 4 5 6 7 8 9 10 11 12 ├── django-devops-nginx │ ├── Dockerfile │ └── nginx.repo ├── django-devops-compose │ ├── docker-compose.yml │ ├── www │ ├── conf │ │ ├── nginx.conf │ ├── log │ │ ├── nginx │ │ │ ├── access.log │ │ │ ├── error.微信公众号DockerServicesToolsDjangoNginxPythonR&DOperationshttps://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-3.htmlSat, 23 Sep 2017 19:56:03 +0000Sat, 23 Sep 2017 19:56:03 +0000https://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-3.html1. Basic Concepts Docker Compose is a Docker tool for defining and running complex applications. With Docker Compose, you can define a multi-container application in a single file, then use a single command to start your application and finish all the preparation work. Docker Compose positions itself as ‘defining and running complex applications with Docker’.微信公众号DockerServicesToolsDjangoPythonR&DOperationshttps://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-2.htmlFri, 22 Sep 2017 19:52:27 +0000Fri, 22 Sep 2017 19:52:27 +0000https://www.chenshaowen.com/en/blog/how-to-package-django-development-environments-using-docker-2.html1. Basic Concepts A Dockerfile is a collection of instructions for building a Docker image. Docker reads Dockerfile instructions to build an image automatically. A Dockerfile is similar to a Makefile: both are text files that organize all the instructions in the order the image is built. The command to build a Docker image:微信公众号DockerDjangoPythonServicesToolsR&DOperationshttps://www.chenshaowen.com/en/blog/atom-create-lightweight-python-full-stack-ide.htmlSun, 06 Aug 2017 14:51:16 +0000Sun, 06 Aug 2017 14:51:16 +0000https://www.chenshaowen.com/en/blog/atom-create-lightweight-python-full-stack-ide.htmlAt the moment I use PyCharm as my integrated development tool for both front end and back end. My main stack is JavaScript, CSS, ECMAScript 6, Vue, Python, Django, Mako, and Markdown. Front-end work has been growing steadily lately, and PyCharm seems to be struggling. Atom, Sublime Text, and Visual Studio Code became the candidates; Atom is maintained by GitHub, has better community support, and is more configurable and more fun to play with.微信公众号ToolsPythonR&DIDEAtomFull-Stackhttps://www.chenshaowen.com/en/blog/django-forms-function.htmlFri, 21 Jul 2017 21:29:40 +0000Fri, 21 Jul 2017 21:29:40 +0000https://www.chenshaowen.com/en/blog/django-forms-function.html1. Automatically Generating HTML Form Elements A Widget is the tool used to render an HTML element. Specifying a widget 1 2 3 4 5 6 from django import forms class CommentForm(forms.Form): name = forms.CharField() url = forms.URLField() comment = forms.CharField(widget=forms.Textarea) Output of CommentForm().as_table() 1 2 3 4 5 6微信公众号DjangoPythonSecurityR&Dhttps://www.chenshaowen.com/en/blog/sql-code-about-django-orm.htmlFri, 21 Jul 2017 13:21:08 +0000Fri, 21 Jul 2017 13:21:08 +0000https://www.chenshaowen.com/en/blog/sql-code-about-django-orm.html1. Basic Concepts ORM: Object Relational Mapping. Its job is to map between a relational database and objects. No complex SQL statements are needed — operating on data is as simple as operating on objects. QuerySet: the list of objects for a given model. A QuerySet lets you read data微信公众号DjangoPythonDataSQLR&Dhttps://www.chenshaowen.com/en/blog/haystack-full-text-search.htmlFri, 21 Jul 2017 13:00:03 +0000Fri, 21 Jul 2017 13:00:03 +0000https://www.chenshaowen.com/en/blog/haystack-full-text-search.htmlA quick word on the project requirements: the team needed to publish documentation externally. The documents are written in Markdown and need to be published as HTML. At first we used an Nginx + Jekyll solution. As the documentation grew, the document system developed a strong need for search. I微信公众号DjangoPythonDataDesignSearchR&Dhttps://www.chenshaowen.com/en/blog/signal-of-django.htmlThu, 13 Jul 2017 13:06:10 +0000Thu, 13 Jul 2017 13:06:10 +0000https://www.chenshaowen.com/en/blog/signal-of-django.html1. Basic Concepts Django ships with a signal dispatcher built in. Signals help decouple program modules. When an event occurs elsewhere in the application, a designated function is notified. Signals let certain senders notify a group of receivers that some action has taken place. 2. Using Signals 2.1 Declaring a微信公众号DjangoBackendPythonR&DLearningDecouplingEventshttps://www.chenshaowen.com/en/blog/class-based-view-of-django.htmlTue, 11 Jul 2017 16:36:56 +0000Tue, 11 Jul 2017 16:36:56 +0000https://www.chenshaowen.com/en/blog/class-based-view-of-django.htmlDjango has two kinds of views: function-based views and class-based views. The role of a view is mainly to fill in logic and return a response body. Function-based views are hard to extend and have a low rate of code reuse. Class-based views, on the other hand, can use inheritance微信公众号DjangoBackendPythonClass-Based ViewsR&Dhttps://www.chenshaowen.com/en/blog/permissions-of-django-rest-framework.htmlFri, 07 Jul 2017 06:47:19 +0000Fri, 07 Jul 2017 06:47:19 +0000https://www.chenshaowen.com/en/blog/permissions-of-django-rest-framework.html1. Permission Management in DRF Permission management in Django REST Framework consists of two parts. One is Authentication. It specifies how the user is authenticated, obtaining request.user. The other is Permissions. It performs permission control over Django resources and user categories. 1.1 Authentication Methods The relevant source is in the rest_framework/authentication.微信公众号DjangoPythonBackendSecurityAPIPermissionsR&Dhttps://www.chenshaowen.com/en/blog/django-template-inherit.htmlMon, 03 Jul 2017 19:17:11 +0000Mon, 03 Jul 2017 19:17:11 +0000https://www.chenshaowen.com/en/blog/django-template-inherit.html1. The Scenario In a project, elements such as the header and footer are often reused. To avoid rewriting these elements on every page, and so that a change does not require editing each page individually, the common parts need to be extracted — that is Django template inheritance. 2.微信公众号DjangoPythonTemplatesR&Dhttps://www.chenshaowen.com/en/blog/django-decorator.htmlThu, 22 Jun 2017 23:55:59 +0000Thu, 22 Jun 2017 23:55:59 +0000https://www.chenshaowen.com/en/blog/django-decorator.htmlWhen developing with a separated front end and back end, some of the API endpoints provided to the front end use GET requests and some use POST requests. To keep the back end from throwing an error while reading values from request in views.py, you had to check the request微信公众号DjangoDemoDecoratorsPythonhttps://www.chenshaowen.com/en/blog/snippets-of-django.htmlThu, 22 Jun 2017 23:52:06 +0000Thu, 22 Jun 2017 23:52:06 +0000https://www.chenshaowen.com/en/blog/snippets-of-django.html1. Auto-Register All Models in Admin admin.py 1 2 3 4 5 6 7 8 9 10 # -*- coding: utf-8 -*- import inspect from django.contrib import admin from . import models for name, obj in inspect.getmembers(models): try: if inspect.isclass(obj): admin.site.register(getattr(models, name)) except Exception as e: pass 2. Get All View Names Get all view names of the project微信公众号DjangoPythonR&DLearningTipshttps://www.chenshaowen.com/en/blog/101-of-django-rest-framework.htmlThu, 22 Jun 2017 23:50:15 +0000Thu, 22 Jun 2017 23:50:15 +0000https://www.chenshaowen.com/en/blog/101-of-django-rest-framework.htmlIn the SaaS development I work on, there is a fairly high demand for development efficiency. From project initiation, prototype design and evaluation, requirements confirmation, frontend design, and backend development through to final acceptance, we complete one iteration in just a few weeks. Guided by agile development, we began rolling微信公众号DataBackendInterfaceDjangoPythonAPIR&Dhttps://www.chenshaowen.com/en/blog/restful-api-of-using-django-tastypie.htmlTue, 13 Jun 2017 21:31:13 +0000Tue, 13 Jun 2017 21:31:13 +0000https://www.chenshaowen.com/en/blog/restful-api-of-using-django-tastypie.html1. Restful REST is short for Representational State Transfer, meaning “representation state transfer”. Restful is a development philosophy and a software architecture style for the World Wide Web. 1.1 Features of Restful Abstract resources Images, text, songs, and videos are all resource entities; on the network they are abstracted as微信公众号DjangoPythonInterfaceAPITastypieR&Dhttps://www.chenshaowen.com/en/blog/manage-command-in-django.htmlMon, 15 May 2017 21:14:48 +0000Mon, 15 May 2017 21:14:48 +0000https://www.chenshaowen.com/en/blog/manage-command-in-django.htmlEvery Django project automatically generates a manage.py file. manage.py is a simple wrapper around django-admin; its job is to put the Django Project into the sys.path directory and set the DJANGO_SETTINGS_MODULE environment variable to the current Project’s settings.py file. In other words, the difference between django-admin and manage is that微信公众号DjangoPythonToolsCommandR&Dhttps://www.chenshaowen.com/en/blog/how-to-build-reusable-django-app.htmlFri, 05 May 2017 21:43:47 +0000Fri, 05 May 2017 21:43:47 +0000https://www.chenshaowen.com/en/blog/how-to-build-reusable-django-app.htmlThe team I work on is responsible for SaaS development and carries almost all of the center’s SaaS needs. Among these there are long-term maintenance projects and short-term crunch demo projects, and everyone wears several hats. Of course, the development platform is also open to other people to use, and the whole platform has hundreds if not thousands of SaaS applications.微信公众号DjangoPythonManagementR&DArchitecturehttps://www.chenshaowen.com/en/blog/book/dive-into-python.htmlFri, 24 Feb 2017 13:11:11 +0000Fri, 24 Feb 2017 13:11:11 +0000https://www.chenshaowen.com/en/blog/book/dive-into-python.htmlAuthor: Mark Pilgrim Publisher: Apress Published: 2004-07-19 ISBN: 9781590593561微信公众号BooksPythonLearningProgrammingReadinghttps://www.chenshaowen.com/en/blog/drawing-2d-fractal-graph-using-python.htmlWed, 25 Jan 2017 23:28:00 +0000Wed, 25 Jan 2017 23:28:00 +0000https://www.chenshaowen.com/en/blog/drawing-2d-fractal-graph-using-python.html1. Koch Curve The Swedish mathematician Helge von Koch proposed the Koch curve in his 1904 paper “On a continuous curve without tangents, constructible from elementary geometry.” It is described as follows: Specify the length of a line segment \(l\) (this can be thought of as iteration 0) Divide this微信公众号PythonMathR&DFractalLearningVisualizationDrawinghttps://www.chenshaowen.com/en/blog/django-permissions-control.htmlSun, 22 Jan 2017 09:23:45 +0000Sun, 22 Jan 2017 09:23:45 +0000https://www.chenshaowen.com/en/blog/django-permissions-control.html1. Django Built-in Permission Management 1.1 Permission Categories Permission Used to define User A’s permission on Task. User If User A has permission on Model B, then User A has the corresponding permission on all instances in Model B. The user_permission field of the User object is used to manage微信公众号DjangoDevelopmentPermissionsPythonR&DLearningSecurityRBACAuthenticationhttps://www.chenshaowen.com/en/blog/several-methods-of-django-data-migration.htmlTue, 17 Jan 2017 23:29:15 +0000Tue, 17 Jan 2017 23:29:15 +0000https://www.chenshaowen.com/en/blog/several-methods-of-django-data-migration.html1. Background In the course of Web development, migrating data between multiple environments (local, testing, and production) comes up often. This article mainly discusses the possible data migration paths involved in Django development, and seeks feasible methods for them. 2. Scenarios There are four data migration targets in total: the微信公众号DjangoPythonDataMigrationR&Dhttps://www.chenshaowen.com/en/blog/python-coding.htmlTue, 08 Nov 2016 20:21:42 +0000Tue, 08 Nov 2016 20:21:42 +0000https://www.chenshaowen.com/en/blog/python-coding.htmlBackground: I had just finished a Django data-query web project. The data came from internal API queries, and every query had to call several APIs to fetch the data and render it on the front-end page. Since the relevant data does not change often, I designed a cache to improve微信公众号PythonEncodingR&DLearning