How to use JsonPath for Python Json read and write operations

Python Json read and write operations_Detailed explanation of JsonPath usage

1. Introduction

JSONPath is an information extraction class library, which is derived from A tool for extracting specified information from JSON documents, providing multiple language implementation versions, including Javascript, Python, PHP and Java.

The installation method of JSONPath is as follows: pip install jsonpath

Comparing JSONPath syntax and XPATH syntax, JSON has a clear structure, high readability, low complexity, and is very easy to match. . The syntax of JSONPath is similar to XPath. The following table shows the syntax comparison between JSONPath and XPath:

2. Code example

bookJson = {
  "store": {
    "book":[
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ],
    "bicycle": {
      "color": "red",
      "price": 19.95
    }
  }
}

The variable bookJson is already included This JSON string can be deserialized by the following code to obtain a JSON object:

books=json.loads(bookJson)

1) View the color attribute of the bicycle under the store:

checkurl = "$.store.bicycel.color"
print(jsonpath.jsonpath(books, checkurl))
# 输出：['red']

2) Output the content contained in the book node All objects:

checkurl = "$.store.book[*]"
object_list=jsonpath.jsonpath(books, checkurl)
print(object_list)

3) Output the first object of the book node:

checkurl = "$.store.book[0]"
obj = jsonpath.jsonpath(books, checkurl)
print(obj)
# 输出: ['category': 'reference', 'author': 'Nigel Rees', 'title': 'Sayings of the Century', 'price': 8.95}]

4) Output the attribute title values ​​corresponding to all objects in the book node:

checkurl = "$.store.book[*].title"
titles = jsonpath.jsonpath(books, checkurl)
print(titles)
# 输出: ['Sayings of the Century', 'The Lord of the Rings']

5 ) Output all objects in the book node whose category is fiction:

checkurl = "$.store.book[?(@.category=='fiction')]”
books=jsonpath.jsonpath(books, checkurl)
print(books)
# 输出:[{'category': 'fiction', 'author': 'J. R. R. Tolkien', 'title': 'The Lordof the Rings', 'isbn': '0-395-19395-8'， 'price': 22.99}]

6) Output all objects in the book node whose price is less than 10:

checkurl="$.store.book[?(@.price<10)]"
books = jsonpath.jsonpath(books, checkurl)
print(books)
# 输出: [{&#39;category&#39;: &#39;reference&#39;, &#39;author&#39;: &#39;Nigel Rees&#39;, &#39;title&#39;:&#39;Sayings of the Century&#39;, &#39;price&#39;: 8.95}]

7) Output all objects in the book node that contain isb :

checkurl = "$.store.book[?(@.isb)]"
books = jsonpath.jsonpath(books，checkurl)
print(books)
# 输出: [{'category': 'fiction', 'author': 'J. R. R. Tolkien', 'title': 'The Lord of the Rings', 'isbn': '0-395-19395-8'， 'price': 22.99}]

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