jsonquery

Overview

jsonquery is an XPath query package for JSON document, lets you extract data from JSON documents through an XPath expression. Built-in XPath expression cache avoid re-compile XPath expression each query.

Getting Started

Install Package

go get github.com/antchfx/jsonquery

Load JSON document from URL.

doc, err := jsonquery.LoadURL("http://www.example.com/feed?json")

Load JSON document from string.

s :=`{
    "name":"John",
    "age":31, 
    "city":"New York" 
    }`
doc, err := jsonquery.Parse(strings.NewReader(s))

Load JSON document from io.Reader.

f, err := os.Open("./books.json")
doc, err := jsonquery.Parse(f)

Find authors of all books in the store.

list := jsonquery.Find(doc, "store/book/*/author")
// or equal to
list := jsonquery.Find(doc, "//author")
// or by QueryAll()
nodes, err := jsonquery.QueryAll(doc, "//a")

Find the third book.

book := jsonquery.Find(doc, "//book/*[3]")

Find the last book.

book := jsonquery.Find(doc, "//book/*[last()]")

Find all books that have an isbn number.

list := jsonquery.Find(doc, "//book/*[isbn]")

Find all books priced less than 10.

list := jsonquery.Find(doc, "//book/*[price<10]")

Examples

func main() {
	s := `{
		"name": "John",
		"age"      : 26,
		"address"  : {
		  "streetAddress": "naist street",
		  "city"         : "Nara",
		  "postalCode"   : "630-0192"
		},
		"phoneNumbers": [
		  {
			"type"  : "iPhone",
			"number": "0123-4567-8888"
		  },
		  {
			"type"  : "home",
			"number": "0123-4567-8910"
		  }
		]
	}`
	doc, err := jsonquery.Parse(strings.NewReader(s))
	if err != nil {
		panic(err)
	}
	name := jsonquery.FindOne(doc, "name")
	fmt.Printf("name: %s\n", name.InnerText())
	var a []string
	for _, n := range jsonquery.Find(doc, "phoneNumbers/*/number") {
		a = append(a, n.InnerText())
	}
	fmt.Printf("phone number: %s\n", strings.Join(a, ","))
	if n := jsonquery.FindOne(doc, "address/streetAddress"); n != nil {
		fmt.Printf("address: %s\n", n.InnerText())
	}
}

Implement Principle

If you are familiar with XPath and XML, you can easily figure out how to write your XPath expression.

{
"name":"John",
"age":30,
"cars": [
	{ "name":"Ford", "models":[ "Fiesta", "Focus", "Mustang" ] },
	{ "name":"BMW", "models":[ "320", "X3", "X5" ] },
	{ "name":"Fiat", "models":[ "500", "Panda" ] }
]
}

The above JSON document will be convert to similar to XML document by the JSONQuery, like below:

<name>John</name>
<age>30</age>
<cars>
	<element>
		<name>Ford</name>
		<models>
			<element>Fiesta</element>
			<element>Focus</element>
			<element>Mustang</element>
		</models>		
	</element>
	<element>
		<name>BMW</name>
		<models>
			<element>320</element>
			<element>X3</element>
			<element>X5</element>
		</models>		
	</element>
	<element>
		<name>Fiat</name>
		<models>
			<element>500</element>
			<element>Panda</element>
		</models>		
	</element>
</cars>

Notes: element is empty element that have no any name.

List of XPath query packages