jsonpath golang 的使用范例

快速入门

• 安装依赖

go get github.com/oliveagle/jsonpath

• 例子程序

package main

import (
    "encoding/json"
    "fmt"
    // 0. 安装该依赖
    // go get github.com/oliveagle/jsonpath
    "github.com/oliveagle/jsonpath"
)

var dataStr string = `
{
    "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
        }
    },
    "expensive": 10
}
`

func main(){
    test1()
    test2()
    test3()
}

func test1()  {
    // 1. 数据准备把字符串转换到对象内存储
    var json_data interface{}
    json.Unmarshal([]byte(dataStr), &json_data)

    res, err := jsonpath.JsonPathLookup(json_data, "$.expensive")
    if err == nil {
        fmt.Println("step 1 res: $.expensive")
        fmt.Println(res)
    }
}

func test2()  {
    var json_data interface{}
    json.Unmarshal([]byte(dataStr), &json_data)
    //or reuse lookup pattern
    pat, _ := jsonpath.Compile(`$.store.book[?(@.price < $.expensive)].price`)
    res, _ := pat.Lookup(json_data)
    fmt.Println("step 2 res:")
    fmt.Println(res)
}

func test3()  {
    // 3. 未找到对象
    var json_data interface{}
    json.Unmarshal([]byte(dataStr), &json_data)

    res, err := jsonpath.JsonPathLookup(json_data, "$.expensive1")
    if err == nil {
        fmt.Println("step 3 res: $.expensive")
        fmt.Println(res)
    } else {
        fmt.Printf("dddd: %v ",err)
    }
}

符号定义

和java项目github.com/jayway/JsonPath的符号类似，一些差异如下：

Operator	Supported	Description
$	Y	json的根节点. 通常在表达式开始位置.
@	Y	The current node being processed by a filter predicate.
*	X	Wildcard. Available anywhere a name or numeric are required.
..	X	Deep scan. Available anywhere a name is required.
.	Y	Dot-notated child
['' (, '')]	X	Bracket-notated child or children
[ (, )]	Y	Array index or indexes
[start:end]	Y	Array slice operator
[?()]	Y	Filter expression. Expression must evaluate to a boolean value.

例子数据

{
    "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
        }
    },
    "expensive": 10
}

例子数据测试结果

jsonpath	result
$.expensive	10
$.store.book[0].price	8.95
$.store.book[-1].isbn	"0-395-19395-8"
$.store.book[0,1].price	[8.95, 12.99]
$.store.book[0:2].price	[8.95, 12.99, 8.99]
$.store.book[?(@.isbn)].price	[8.99, 22.99]
$.store.book[?(@.price > 10)].title	["Sword of Honour", "The Lord of the Rings"]
.expensive)].price	[8.95, 8.99]
$.store.book[:].price	[8.9.5, 12.99, 8.9.9, 22.99]
$.store.book[?(@.author =~ /(?i).*REES/)].author	"Nigel Rees"

Note: golang 支持正则表达式标志，格式如 (?imsU)pattern