JsonPath小结

在查看DHC Assertions 模块说明的时候,无意间发现assert模块中JsonBody使用了 JSON Path ,兴趣使然,看了下,发现是类似解析xml用到的 XPath。通过路径来获取json对象的属性值

JSON Path提供了javascript与PHP版本

XPath表达式:/store/book[1]/title

JSON Path表达式:.store.book[0].title 或则 x['store']['book'][0]['title']

同时,官网也有提到,像javascript、Python、PHP等语言已经提供了类似JSON Path的能力了。

另外,JSON Path存在以下问题

  • be naturally based on those language characteristics.
  • cover only essential parts of XPath 1.0.
  • be lightweight in code size and memory consumption.
  • be runtime efficient.

 

常用的表达式

$.store.book[(@.length-1)].title

using the symbol '@' for the current object. Filter expressions are supported via the syntax ?(<boolean expr>) as in

$.store.book[?(@.price < 10)].title

 

XPath JSONPath Description
/ $ the root object/element
. @ the current object/element
/ . or [] child operator
.. n/a parent operator
// .. recursive descent. JSONPath borrows this syntax from E4X.
* * wildcard. All objects/elements regardless their names.
@ n/a attribute access. JSON structures don't have attributes.
[] [] subscript operator. XPath uses it to iterate over element collections and for predicates. In Javascript and JSON it is the native array operator.
| [,] Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set.
n/a [start:end:step] array slice operator borrowed from ES4.
[] ?() applies a filter (script) expression.
n/a () script expression, using the underlying script engine.
() n/a grouping in Xpath

 

{ "store": {
    "book": [ 
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      { "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      { "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
    }
  }
}
XPath JSONPath Result
/store/book/author $.store.book[*].author the authors of all books in the store
//author $..author all authors
/store/* $.store.* all things in store, which are some books and a red bicycle.
/store//price $.store..price the price of everything in the store.
//book[3] $..book[2] the third book
//book[last()] $..book[(@.length-1)]
$..book[-1:]
the last book in order.
//book[position()<3] $..book[0,1]
$..book[:2]
the first two books
//book[isbn] $..book[?(@.isbn)] filter all books with isbn number
//book[price<10] $..book[?(@.price<10)] filter all books cheapier than 10
//* $..* all Elements in XML document. All members of JSON structure.

 

 题外话:在了解JSON Path的时候,还发现了解析JSON的其他框架

传送门:http://blog.sina.com.cn/s/blog_6d425e1a01017sg4.html

JsonSQL、jfunk、TaffyDB、linq.js、objeq

 

posted @ 2016-01-07 19:40 draem0507 阅读(...) 评论(...) 编辑 收藏
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