cascadiavsbeautifulsoup
cascadia is a library for Go that provides a CSS selector engine, allowing you to use CSS selectors to select elements from an HTML document.
It is built on top of the html package in the Go standard library, and provides a more efficient and powerful way to select elements from an HTML document.
beautifulsoup is a Python library for pulling data out of HTML and XML files. It creates parse trees from the source code that can be used to extract data from HTML, which is useful for web scraping. With beautifulsoup, you can search, navigate, and modify the parse tree. It sits atop popular Python parsers like lxml and html5lib, allowing users to try out different parsing strategies or trade speed for flexibility.
beautifulsoup has a number of useful methods and attributes that can be used to extract and manipulate data from an HTML or XML document. Some of the key features include:
- Searching the parse tree
You can search the parse tree using the various search methods that beautifulsoup provides, such as find(), find_all(), and select(). These methods take various arguments to search for specific tags, attributes, and text, and return a list of matching elements. - Navigating the parse tree
You can navigate the parse tree using the various navigation methods that beautifulsoup provides, such as next_sibling, previous_sibling, next_element, previous_element, parent, and children. These methods allow you to move up, down, and around the parse tree. - Modifying the parse tree
You can modify the parse tree using the various modification methods that beautifulsoup provides, such as append(), extend(), insert(), insert_before(), and insert_after(). These methods allow you to add new elements to the parse tree, or to change the position of existing elements. - Accessing tag attributes
You can access the attributes of a tag using the attrs property. This property returns a dictionary of the tag's attributes and their values. - Accessing tag text
You can access the text within a tag using the string property. This property returns the text as a string, with any leading or trailing whitespace removed.
With the above feature one can easily extract data out of HTML or XML files. It is widely used in web scraping and other data extraction projects.
It also has features for parsing XML files, special methods for dealing with HTML forms, pretty printing HTML and a few other functionalities.
Highlights
Example Use
package main
import (
"fmt"
"github.com/andybalholm/cascadia"
"golang.org/x/net/html"
"strings"
)
func main() {
// Create an HTML string
html := `<html>
<body>
<div id="content">
<p>Hello, World!</p>
<a href="http://example.com">Example</a>
</div>
</body>
</html>`
// Parse the HTML string into a node tree
doc, err := html.Parse(strings.NewReader(html))
if err != nil {
fmt.Println("Error:", err)
return
}
// Compile the CSS selector
sel, err := cascadia.Compile("p")
if err != nil {
fmt.Println("Error:", err)
return
}
// Use the Selector.Match method to select elements from the document
matches := sel.Match(doc)
if len(matches) > 0 {
fmt.Println(matches[0].FirstChild.Data)
// > Hello, World!
}
}
from bs4 import BeautifulSoup
# this is our HTML page:
html = """
<head>
<title>Hello World!</title>
</head>
<body>
<div id="product">
<h1>Product Title</h1>
<p>paragraph 1</p>
<p>paragraph2</p>
<span class="price">$10</span>
</div>
</body>
"""
soup = BeautifulSoup(html)
# we can iterate using dot notation:
soup.head.title
"Hello World"
# or use find method to recursively find matching elements:
soup.find(class_="price").text
"$10"
# the selected elements can be modified in place:
soup.find(class_="price").string = "$20"
# beautifulsoup also supports CSS selectors:
soup.select_one("#product .price").text
"$20"
# bs4 also contains various utility functions like HTML formatting
print(soup.prettify())
"""
<html>
<head>
<title>
Hello World!
</title>
</head>
<body>
<div id="product">
<h1>
Product Title
</h1>
<p>
paragraph 1
</p>
<p>
paragraph2
</p>
<span class="price">
$20
</span>
</div>
</body>
</html>
"""