Html To Pdf Python Flask
Latrisha Adan
Note: You can use Git, a version control system, to effectively manage and track the development process for your project. To learn how to use Git, you might want to check out our Introduction to Git Installation Usage and Branches article.
You use the python command line interface with the option -c to execute Python code. Next you import the flask package with import flask; then print the Flask version, which is provided via the flask.__version__ variable.
Warning Flask uses a simple web server to serve our application in a development environment, which also means that the Flask debugger is running to make catching errors easier. This development server should not be used in a production deployment. See the Deployment Options page on the Flask documentation for more information, you can also check out this Flask deployment tutorial.
You can now leave the development server running in the terminal and open another terminal window. Move into the project folder where hello.py is located, activate the virtual environment, set the environment variables FLASK_ENV and FLASK_APP, and continue to the next steps. (These commands are listed earlier in this step.)
Opening the URL :5000/ in your browser will result in the debugger page informing you that the index.html template was not found. The main line in the code that was responsible for this error will be highlighted. In this case, it is the line return render_template('index.html').
Then create another directory called css inside the static directory to host .css files. This is typically done to organize static files in dedicated folders, as such, JavaScript files typically live inside a directory called js, images are put in a directory called images (or img), and so on. The following command will create the css directory inside the static directory:
You might have guessed that making another HTML template would mean repeating most of the HTML code you already wrote in the index.html template. You can avoid unnecessary code repetition with the help of a base template file, which all of your HTML files will inherit from. See Template Inheritance in Jinja for more information.
Most of the code in the preceding block is standard HTML and code required for Bootstrap. The tags provide information for the web browser, the tag links the Bootstrap CSS files, and the tags are links to JavaScript code that allows some additional Bootstrap features, check out the Bootstrap documentation for more.
In this new version of the index.html template, you use the % extends % tag to inherit from the base.html template. You then extend it via replacing the content block in the base template with what is inside the content block in the preceding code block.
This content block contains an tag with the text Welcome to FlaskBlog inside a title block, which in turn replaces the original title block in the base.html template with the text Welcome to FlaskBlog. This way, you can avoid repeating the same text twice, as it works both as a title for the page and a heading that appears below the navigation bar inherited from the base template.
You first import the sqlite3 module and then open a connection to a database file named database.db, which will be created once you run the Python file. Then you use the open() function to open the schema.sql file. Next you execute its contents using the executescript() method that executes multiple SQL statements at once, which will create the posts table. You create a Cursor object that allows you to use its execute() method to execute two INSERT SQL statements to add two blog posts to your posts table. Finally, you commit the changes and close the connection.
In this new version of the index() function, you first open a database connection using the get_db_connection() function you defined earlier. Then you execute an SQL query to select all entries from the posts table. You implement the fetchall() method to fetch all the rows of the query result, this will return a list of the posts you inserted into the database in the previous step.
You close the database connection using the close() method and return the result of rendering the index.html template. You also pass the posts object as an argument, which contains the results you got from the database, this will allow you to access the blog posts in the index.html template.
You display the title using a literal variable delimiter ( ... ). Remember that post will be a dictionary-like object, so you can access the post title with post['title']. You also display the post creation date using the same method.
Inside the function, you use the get_db_connection() function to open a database connection and execute a SQL query to get the blog post associated with the given post_id value. You add the fetchone() method to get the result and store it in the post variable then close the connection. If the post variable has the value None, meaning no result was found in the database, you use the abort() function you imported earlier to respond with a 404 error code and the function will finish execution. If however, a post was found, you return the value of the post variable.
Type the following code in this new post.html file. This will be similar to the index.html file, except that it will only display a single post, in addition to also displaying the contents of the post:
You can now navigate to the following URLs to see the two posts you have in your database, along with a page that tells the user that the requested blog post was not found (since there is no post with an ID number of 3 so far):
Here, you pass 'post' to the url_for() function as a first argument. This is the name of the post() view function and since it accepts a post_id argument, you give it the value post['id']. The url_for() function will return the proper URL for each post based on its ID.
The value of the post title input is request.form['title'] and the text area has the value request.form['content'] , this is done so that the data you enter does not get lost if something goes wrong. For example, if you write a long post and you forget to give it a title, a message will be displayed informing you that the title is required. This will happen without losing the post you wrote since it will be stored in the request global object that you have access to in your templates.
This form submits a POST request to your create() view function. However, there is no code to handle a POST request in the function yet, so nothing happens after filling in the form and submitting it.
You then extract the submitted title and content from the request.form object that gives you access to the form data in the request. If the title is not provided, the condition if not title would be fulfilled, displaying a message to the user informing them that the title is required. If, on the other hand, the title is provided, you open a connection with the get_db_connection() function and insert the title and the content you received into the posts table.
You then commit the changes to the database and close the connection. After adding the blog post to the database, you redirect the client to the index page using the redirect() function passing it the URL generated by the url_for() function with the value 'index' as an argument.
Edit the file by adding a new
- tag following the About link inside the tag. Then add a new for loop directly above the content block to display the flashed messages below the navigation bar. These messages are available in the special get_flashed_messages() function Flask provides:
The post you edit is determined by the URL and Flask will pass the ID number to the edit() function via the id argument. You add this value to the get_post() function to fetch the post associated with the provided ID from the database. The new data will come in a POST request, which is handled inside the if request.method == 'POST' condition.
Just like when you create a new post, you first extract the data from the request.form object then flash a message if the title has an empty value, otherwise, you open a database connection. Then you update the posts table by setting a new title and new content where the ID of the post in the database is equal to the ID that was in the URL.
This code follows the same pattern except for the request.form['title'] or post['title'] and request.form['content'] or post['content'] syntax. This displays the data stored in the request if it exists, otherwise it displays the data from the post variable that was passed to the template containing current database data.
However you can access this route via a form that sends a POST request passing in the ID of the post you want to delete. The function will receive the ID value and use it to get the post from the database with the get_post() function.
Then you open a database connection and execute a DELETE FROM SQL command to delete the post. You commit the change to the database and close the connection while flashing a message to inform the user that the post was successfully deleted and redirect them to the index page.
This tutorial introduced essential concepts of the Flask Python framework. You learned how to make a small web application, run it in a development server, and allow the user to provide custom data via URL parameters and web forms. You also used the Jinja template engine to reuse HTML files and use logic in them. At the end of this tutorial, you now have a fully functioning web blog that interacts with an SQLite database to create, display, edit, and delete blog posts using the Python language and SQL queries. If you would like to learn more about working with Flask and SQLite check out this tutorial on How To Use One-to-Many Database Relationships with Flask and SQLite.
You can further develop this application by adding user authentication so that only registered users can create and modify blog posts, you may also add comments and tags for each blog post, and add file uploads to give users the ability to include images in the post. See the Flask documentation for more information.
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