10060nam a22002177a 4500 2435 2435 OSt 20200224131928.0 200117b ||||| |||| 00| 0 eng d 978-93-5213-699-5 Allied Informatics, Jaipur 7084 13/01/2020 2019-20 BSDU English BSDU 006.8 GRI Grinberg, Miguel Flask Web Development: Developing web applications with python 2nd Mumbai Shroff Publishers & Distributors Pvt. Ltd. 2019 291 Take full creative control of your web applications with Flask, the Python-based microframework. With the second edition of this hands-on book, you’ll learn Flask from the ground up by developing a complete, real-world application created by author Miguel Grinberg. This refreshed edition accounts for important technology changes that have occurred in the past three years. Explore the framework’s core functionality, and learn how to extend applications with advanced web techniques such as database migrations and an application programming interface. The first part of each chapter provides you with reference and background for the topic in question, while the second part guides you through a hands-on implementation. If you have Python experience, you’re ready to take advantage of the creative freedom Flask provides. Three sections include: A thorough introduction to Flask: explore web application development basics with Flask and an application structure appropriate for medium and large applications Building Flasky: learn how to build an open source blogging application step-by-step by reusing templates, paginating item lists, and working with rich text Going the last mile: dive into unit testing strategies, performance analysis techniques, and deployment options for your Flask application Contents Table of Contents Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Part I. Introduction to Flask 1. Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Creating the Application Directory 2 Virtual Environments 2 Creating a Virtual Environment with Python 3 3 Creating a Virtual Environment with Python 2 3 Working with a Virtual Environment 4 Installing Python Packages with pip 5 2. Basic Application Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Initialization 7 Routes and View Functions 8 A Complete Application 9 Development Web Server 10 Dynamic Routes 12 Debug Mode 13 Command-Line Options 15 The Request-Response Cycle 17 Application and Request Contexts 17 Request Dispatching 18 The Request Object 19 Request Hooks 20 Responses 21 Flask Extensions 23 v 3. Templates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 The Jinja2 Template Engine 26 Rendering Templates 26 Variables 27 Control Structures 28 Bootstrap Integration with Flask-Bootstrap 30 Custom Error Pages 33 Links 36 Static Files 37 Localization of Dates and Times with Flask-Moment 38 4. Web Forms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Configuration 44 Form Classes 44 HTML Rendering of Forms 47 Form Handling in View Functions 48 Redirects and User Sessions 51 Message Flashing 53 5. Databases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 SQL Databases 57 NoSQL Databases 58 SQL or NoSQL? 59 Python Database Frameworks 59 Database Management with Flask-SQLAlchemy 61 Model Definition 62 Relationships 64 Database Operations 66 Creating the Tables 66 Inserting Rows 66 Modifying Rows 68 Deleting Rows 68 Querying Rows 68 Database Use in View Functions 71 Integration with the Python Shell 72 Database Migrations with Flask-Migrate 73 Creating a Migration Repository 73 Creating a Migration Script 74 Upgrading the Database 75 Adding More Migrations 76 vi | Table of Contents 6. Email. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 Email Support with Flask-Mail 79 Sending Email from the Python Shell 81 Integrating Emails with the Application 81 Sending Asynchronous Email 83 7. Large Application Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Project Structure 85 Configuration Options 86 Application Package 88 Using an Application Factory 88 Implementing Application Functionality in a Blueprint 90 Application Script 93 Requirements File 93 Unit Tests 94 Database Setup 96 Running the Application 97 Part II. Example: A Social Blogging Application 8. User Authentication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Authentication Extensions for Flask 101 Password Security 102 Hashing Passwords with Werkzeug 102 Creating an Authentication Blueprint 105 User Authentication with Flask-Login 107 Preparing the User Model for Logins 107 Protecting Routes 108 Adding a Login Form 109 Signing Users In 111 Signing Users Out 112 Understanding How Flask-Login Works 113 Testing Logins 114 New User Registration 115 Adding a User Registration Form 115 Registering New Users 117 Account Confirmation 118 Generating Confirmation Tokens with itsdangerous 118 Sending Confirmation Emails 120 Account Management 125 Table of Contents | vii 9. User Roles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Database Representation of Roles 127 Role Assignment 131 Role Verification 132 10. User Pro€les. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Profile Information 137 User Profile Page 138 Profile Editor 141 User-Level Profile Editor 141 Administrator-Level Profile Editor 143 User Avatars 146 11. Blog Posts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Blog Post Submission and Display 151 Blog Posts on Profile Pages 154 Paginating Long Blog Post Lists 155 Creating Fake Blog Post Data 155 Rendering in Pages 157 Adding a Pagination Widget 158 Rich-Text Posts with Markdown and Flask-PageDown 161 Using Flask-PageDown 162 Handling Rich Text on the Server 164 Permanent Links to Blog Posts 165 Blog Post Editor 167 12. Followers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Database Relationships Revisited 171 Many-to-Many Relationships 172 Self-Referential Relationships 174 Advanced Many-to-Many Relationships 174 Followers on the Profile Page 178 Querying Followed Posts Using a Database Join 181 Showing Followed Posts on the Home Page 183 13. User Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 Database Representation of Comments 189 Comment Submission and Display 191 Comment Moderation 193 14. Application Programming Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Introduction to REST 199 viii | Table of Contents Resources Are Everything 200 Request Methods 201 Request and Response Bodies 201 Versioning 202 RESTful Web Services with Flask 203 Creating an API Blueprint 203 Error Handling 204 User Authentication with Flask-HTTPAuth 206 Token-Based Authentication 208 Serializing Resources to and from JSON 210 Implementing Resource Endpoints 213 Pagination of Large Resource Collections 216 Testing Web Services with HTTPie 217 Part III. The Last Mile 15. Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 Obtaining Code Coverage Reports 221 The Flask Test Client 224 Testing Web Applications 225 Testing Web Services 228 End-to-End Testing with Selenium 230 Is It Worth It? 234 16. Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Logging Slow Database Performance 237 Source Code Profiling 239 17. Deployment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 Deployment Workflow 241 Logging of Errors During Production 242 Cloud Deployment 243 The Heroku Platform 244 Preparing the Application 244 Testing with Heroku Local 253 Deploying with git push 254 Deploying an Upgrade 255 Docker Containers 256 Installing Docker 256 Building a Container Image 257 Running a Container 261 Table of Contents | ix Inspecting a Running Container 262 Pushing Your Container Image to an External Registry 263 Using an External Database 264 Container Orchestration with Docker Compose 265 Cleaning Up Old Containers and Images 269 Using Docker in Production 270 Traditional Deployments 270 Server Setup 271 Importing Environment Variables 271 Setting Up Logging 272 18. Additional Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 Using an Integrated Development Environment (IDE) 275 Finding Flask Extensions 276 Getting Help 276 Getting Involved with Flask 277 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 x | Table of Contents Python ddc BK 0 0 ddc 0 0 BSDU BSDU GEN 2020-01-17 750.00 1 006.8 GRI 017989 2022-10-15 00:00:00 2022-10-01 750.00 2020-01-17 BK