Detailed explanation of Python's sample code for modifying content using the Beautiful Soup module

Beautiful Soup is a Python library that can extract data from HTML or XML files. It enables you to navigate, find, and modify documents in your usual way through your favorite converter. He can also modify the content of HTML/XML documents. This article mainly introduces how Python uses the Beautiful Soup module to modify content. Friends in need can refer to it.

Preface

In fact, in addition to searching and navigating, the Beautiful Soup module can also modify the content of HTML/XML documents. This means being able to add or delete tags, modify tag names, change tag attribute values, modify text content, and more. This article introduces to you in great detail how Python uses the Beautiful Soup module to modify content. I won’t go into details below, but let’s take a look at the detailed introduction.

Modify tag

The sample HTML document used is still as follows:

html_markup="""
 <p class="ecopyramid">
 <ul id="producers">
  <li class="producerlist">
  <p class="name">plants</p>
  <p class="number">100000</p>
  </li>
  <li class="producerlist">
  <p class="name">algae</p>
  <p class="number">100000</p>
  </li>
 </ul>
 </p>
 """

Modify tag name

soup = BeautifulSoup(html_markup,'lxml')
producer_entries = soup.ul
print producer_entries.name
producer_entries.name = "p"
print producer_entries.prettify()

Modify the tag attribute value

# 修改标签属性
# 更新标签现有的属性值
producer_entries['id'] = "producers_new_value"
print producer_entries.prettify()
# 标签添加新的属性值
producer_entries['class'] = "newclass"
print producer_entries.prettify()
# 删除标签属性值
del producer_entries['class']
print producer_entries.prettify()

Add a new tag

We can use the new_tag method to generate a new tag, and then use the append() , insert(), insert_after(), insert_before() methods to add the tag to HTML In the tree.

For example, add a li tag to the ul tag of the above HTML document. First, a new li tag is generated and then inserted into the HTML tree structure. And insert the corresponding p tag in the li tag.

# 添加新的标签
# new_tag 生成一个 tag 对象
new_li_tag = soup.new_tag("li")
# 标签对象添加属性的方法
new_atag = soup.new_tag("a",href="www.example.com" rel="external nofollow" )
new_li_tag.attrs = {'class':'producerlist'}
soup = BeautifulSoup(html_markup,'lxml')
producer_entries = soup.ul
# 使用 append() 方法添加到末尾
producer_entries.append(new_li_tag)
print producer_entries.prettify()
# 生成两个 p 标签,将其插入到 li 标签中
new_p_name_tag = soup.new_tag("p")
new_p_name_tag['class'] = "name"
new_p_number_tag = soup.new_tag("p")
new_p_number_tag["class"] = "number"
# 使用 insert() 方法指定位置插入
new_li_tag.insert(0,new_p_name_tag)
new_li_tag.insert(1,new_p_number_tag)
print new_li_tag.prettify()

Modify the string content

You can use new_string(), append( ), insert() method.

# 修改字符串内容
# 使用 .string 属性修改字符串内容
new_p_name_tag.string = 'new_p_name'
# 使用 .append() 方法添加字符串内容
new_p_name_tag.append("producer")
# 使用 soup 对象的 new_string() 方法生成字符串
new_string_toappend = soup.new_string("producer")
new_p_name_tag.append(new_string_toappend)
# 使用insert() 方法插入
new_string_toinsert = soup.new_string("10000")
new_p_number_tag.insert(0,new_string_toinsert)
print producer_entries.prettify()

Delete label nodes

Beautiful Soup module provides decompose() and extract() methods to delete nodes .

decompose() The method to delete a node will not only delete the current node, but also delete all its child nodes.

extract() method is used to delete nodes or string content from the HTML tree.

# 删除节点
third_producer = soup.find_all("li")[2]
# 使用 decompose() 方法删除 p 节点
p_name = third_producer.p
p_name.decompose()
print third_producer.prettify()
# 使用 extract() 方法删除节点
third_producer_removed = third_producer.extract()
print soup.prettify()

Delete tag content

A tag may have a NavigableString object or a Tag object as its child nodes. To remove all these child nodes, use clear( ) method. This will remove all .content from the tag.

Other methods for modifying content

In addition to the methods mentioned above, there are other methods for modifying content.

insert_after() and insert_before() Methods

The above two methods can insert a label before or after the label or string or string. Methods can only accept one parameter, either a NavigableString object or a Tag object.

replace_with() Method

This method is to replace the original label or string with a new label or string content, and can receive a label or string as enter.

wrap() and unwrap() Method

wrap() The method is to wrap a tag with another tag label or string.

unwrap() method is the opposite of wrap() method.

# wrap()方法
li_tags = soup.find_all('li')
for li in li_tags:
 new_p_tag = soup.new_tag('p')
 li.wrap(new_p_tag)
print soup.prettify()
# unwrap()方法
li_tags = soup.find_all("li")
for li in li_tags:
 li.p.unwrap()
print soup.prettify()

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