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

Name	Description
htmlquery	XPath query package for the HTML document
xmlquery	XPath query package for the XML document
jsonquery	XPath query package for the JSON document