c:\\code\\test\\mysite<\/code><\/p>\nI then enter that directory to make sure any commands I do take place within it. I need a virtual environment to house Flask. When I install Flask, I don’t want to do it system-wide. This part was pretty simple too:<\/p>\n
virtualenv venv<\/code><\/p>\n(Remember, the venv<\/code> at the end is just the name of the directory the virtualenv will be installed into. You can actually name it anything you want, but \u00a0venv<\/code> is standard practice.) After creating the virtual environment, I need to enter it. I do this by running the activate<\/code> script in the Scripts<\/code> sub-directory:<\/p>\nvenv\\Scripts\\activate<\/code><\/p>\nThe prompt now changes to show that the virtual environment is active. If I wish to exit the virtual environment, all I need to do is type deactivate<\/code>. Finally, I need to install Flask into the virtual environment using pip<\/code>. This is quite simple:<\/p>\npip install flask<\/code><\/p>\nBoom! All done! Flask is installed into a virtual environment and ready to use. I should note that the file structure here is different from the one noted in\u00a0Miguel Grinberg’s Flask tutorial<\/a>. Miguels says that the file structure should look like this:<\/p>\nmicroblog\\\r\n\u00a0 \u00a0 flask\\\r\n <virtual environment files>\r\n\u00a0 \u00a0 app\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 static\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 templates\\\r\n __init__.py\r\n views.py\r\n\u00a0 \u00a0 tmp\\\r\n run.py<\/pre>\nBut I find that mine looks like this:<\/p>\n
mysite\\\r\n\u00a0 \u00a0 venv\\\r\n\u00a0 \u00a0 \u00a0 \u00a0\u00a0include\\\r\n\u00a0 \u00a0 \u00a0 \u00a0\u00a0Lib\\\r\n\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 __pycache__\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 collections\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 distutils\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 encodings\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 importlib\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 site-packages\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 flask\\\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 <other packages>\r\n\u00a0 \u00a0 \u00a0 \u00a0\u00a0Scripts\\<\/pre>\nI can think of a few reasons why this might be. For starters,\u00a0this entry was last updated in September 2014. About a year ago. Flask may have changed a lot since then. Another reason for the difference might be that I’m doing this on Windows and Miguel was doing it on Linux and they change things between systems. I will have to investigate this more and find out why there are discrepancies.<\/p>\n
EDIT: Aha! I found one of the discrepancies! In the tutorial, Miguel uses the command virtualenv flask<\/code> instead of virtualenv venv<\/code>. That would explain why he has a folder titled “flask” in his microblog<\/code> directory.<\/p>\nHere’s the purpose of\u00a0the other folders he created:<\/p>\n
The app<\/code><\/span> folder will be where we will put our application package.
\nThe static<\/code><\/span> sub-folder is where we will store static files like images, javascripts, and cascading style sheets.
\nThe templates<\/code><\/span> sub-folder is obviously where our templates will go.<\/p><\/blockquote>\nAnd here are the files that he created:<\/p>\n
__init__.py<\/span><\/code><\/p>\nfrom flask import Flask\r\n\r\napp = Flask(__name__)\r\nfrom app import views<\/pre>\nThe\u00a0__init__.py<\/span><\/code>\u00a0file’s purpose is to create the application object (of class Flask<\/code><\/span>) and then import the views<\/code><\/span> module.\u00a0The views are the handlers that respond to requests from web browsers or other clients. In Flask handlers are written as Python functions. Each view function is mapped to one or more request URLs.<\/p>\nviews.py<\/span><\/code><\/p>\nfrom app import app\r\n\r\n@app.route('\/')\r\n@app.route('\/index')\r\ndef index():\r\n return \"Hello, World!\"<\/pre>\nThe function in the views.py<\/code> <\/span>file just returns a string, to be displayed on the client’s web browser. The two route<\/code><\/span> decorators above the function create the mappings from URLs \/<\/code><\/span> and\u00a0\/index<\/code><\/span> to this function.<\/p>\nrun.py<\/code><\/span><\/p>\n#!flask\/bin\/python\r\nfrom app import app\r\napp.run(debug=True)<\/pre>\nThe run.py script starts up the development web server with our application. It imports the app<\/code><\/span> variable from our app package and invokes its run<\/code><\/span> method to start the server.<\/p>\nFinally, I should mention that I am a very visual learner, so the following drawing is my understanding of what’s happening when you enter\u00a0flask\\Scripts\\python run.py<\/code>:<\/p>\n![\"what's](\"https:\/\/www.tayloraliss.com\/blog\/wp-content\/uploads\/2015\/08\/whats-going-on-300x203.png\")
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