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|
// gitissue #28
/*
(reference: http://goessner.net/articles/JsonPath/)
Let's practice JSONPath expressions by some more examples. We start with a simple JSON structure built after an XML example representing a bookstore (original XML file).
{ "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.
*/
package main
import (
"fmt"
"github.com/clbanning/mxj/v2"
)
var data = []byte(`
{ "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
}
}
}`)
func main() {
m, err := mxj.NewMapJson(data)
if err != nil {
fmt.Println("NewMapJson err:", err)
return
}
// $.store.book[*].author the authors of all books in the store
list, err := m.ValuesForPath("store.book.author")
if err != nil {
fmt.Println("book author err:", err)
return
}
fmt.Println("authors:", list)
// $..author all authors
list, err = m.ValuesForKey("author")
if err != nil {
fmt.Println("author err:", err)
return
}
fmt.Println("authors:", list)
// $.store.* all things in store, which are some books and a red bicycle.
list, err = m.ValuesForKey("store")
if err != nil {
fmt.Println("store things err:", err)
}
fmt.Println("store things:", list)
// /store//price $.store..price the price of everything in the store.
list, err = m.ValuesForKey("price")
if err != nil {
fmt.Println("price of things err:", err)
}
fmt.Println("price of things:", list)
// $..book[2] the third book
v, err := m.ValueForPath("store.book[2]")
if err != nil {
fmt.Println("price of things err:", err)
}
fmt.Println("3rd book:", v)
// $..book[-1:] the last book in order
list, err = m.ValuesForPath("store.book")
if err != nil {
fmt.Println("list of books err:", err)
}
if len(list) <= 1 {
fmt.Println("last book:", list)
} else {
fmt.Println("last book:", list[len(list)-1:])
}
// $..book[:2] the first two books
list, err = m.ValuesForPath("store.book")
if err != nil {
fmt.Println("list of books err:", err)
}
if len(list) <= 2 {
fmt.Println("1st 2 books:", list)
} else {
fmt.Println("1st 2 books:", list[:2])
}
// $..book[?(@.isbn)] filter all books with isbn number
list, err = m.ValuesForPath("store.book", "isbn:*")
if err != nil {
fmt.Println("list of books err:", err)
}
fmt.Println("books with isbn:", list)
// $..book[?(@.price<10)] filter all books cheapier than 10
list, err = m.ValuesForPath("store.book")
if err != nil {
fmt.Println("list of books err:", err)
}
var n int
for _, v := range list {
if v.(map[string]interface{})["price"].(float64) >= 10.0 {
continue
}
list[n] = v
n++
}
list = list[:n]
fmt.Println("books with price < $10:", list)
// $..* all Elements in XML document. All members of JSON structure.
// 1st where values are not complex elements
list = m.LeafValues()
fmt.Println("list of leaf values:", list)
// $..* all Elements in XML document. All members of JSON structure.
// 2nd every value - even complex elements
path := "*"
list = make([]interface{}, 0)
for {
v, _ := m.ValuesForPath(path)
if len(v) == 0 {
break
}
list = append(list, v...)
path = path + ".*"
}
fmt.Println("list of all values:", list)
}
|
