README.md. Update about tutorial and test case.

Author: zhengchun

README.md

@@ -1,128 +1,230 @@
-jsonquery
-====
+# jsonquery
+
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 [![Coverage Status](https://coveralls.io/repos//antchfx/jsonquery/badge.svg?branch=master)](https://coveralls.io//antchfx/jsonquery?branch=master)
 [![GoDoc](https://godoc.org/.com/antchfx/jsonquery?status.svg)](https://godoc.org/.com/antchfx/jsonquery)
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-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.
+# Overview
 
+[jsonquery](https://.com/antchfx/jsonquery) is XPath query package for JSON document depended on [xpath](https://.com/antchfx/xpath) package, writing in go.
 
-XPath query for Golang
-===
+jsonquery helps you easy to extract any data from JSON using XPath query without using pre-defined object structure to unmarshal in go, saving your time.
 
 - [htmlquery](https://.com/antchfx/htmlquery) - XPath query package for HTML document
 
 - [xmlquery](https://.com/antchfx/xmlquery) - XPath query package for XML document.
 
-- [jsonquery](https://.com/antchfx/jsonquery) - XPath query package for JSON document
+### Install Package
 
+```
+go get .com/antchfx/jsonquery
+```
 
-Getting Started
-===
+## Get Started
 
-### Install Package
+The below code may be help your understand what it does. We don't need pre-defined strcutre or using regexp to extract some data in JSON file, gets any data is easy and fast in jsonquery now.
+
+```go
+s := `{
+"name":"John",
+"age":31,
+"female":false,
+"city":null
+}`
+doc, err := jsonquery.Parse(strings.NewReader(s))
+if err != nil {
+panic(err)
+}
+// iterate all json objects from child ndoes.
+for _, n := range doc.ChildNodes() {
+fmt.Printf("%s: %v[%T]\n", n.Data, n.Value(), n.Value())
+}
+// xpath query
+n := jsonquery.FindOne(doc, "//age")
+fmt.Printf("age: %.2f", n.Value().(float64))
+// select a child node with `age`. = jsonquery.FindOne(doc,"age")
+m := doc.SelectElement("age")
 ```
-go get .com/antchfx/jsonquery
+
+// Output:
+
 ```
+name: John[string]
+age: 31[float64]
+female: false[bool]
+city: <nil>[<nil>]
+```
+
+The default Json types and Go types are:
 
-#### Load JSON document from URL.
+| JSON | jsonquery(go) |
+| ------- | ------------- |
+| object | interface{} |
+| string | string |
+| number | float64 |
+| boolean | bool |
+| array | []interface{} |
+| null | nil |
+
+For more information about JSON & Go see the https://go.dev/blog/json
+
+## Getting Started
+
+#### Load JSON from URL.
 
 ```go
 doc, err := jsonquery.LoadURL("http://www.example.com/feed?json")
 ```
 
-#### Load JSON document from string.
+#### Load JSON from string.
 
 ```go
 s :=`{
 "name":"John",
-"age":31,
-"city":"New York"
+"age":31,
+"city":"New York"
 }`
 doc, err := jsonquery.Parse(strings.NewReader(s))
 ```
 
-#### Load JSON document from io.Reader.
+#### Load JSON from io.Reader.
 
 ```go
 f, err := os.Open("./books.json")
 doc, err := jsonquery.Parse(f)
 ```
 
-#### Find authors of all books in the store.
+#### Parse JSON array
+
+```go
+s := `[1,2,3,4,5,6]`
+doc, _ := jsonquery.Parse(strings.NewReader(s))
+list := jsonquery.Find(doc, "*")
+for _, n := range list {
+fmt.Print(n.Value().(float64))
+}
+```
+// Output: `1,2,3,4,5,6`
+
+#### Convert JSON object to XML
+```go
+doc, _ := jsonquery.Parse(strings.NewReader(s))
+fmt.Println(doc.OutputXML())
+```
+
+### Methods
+
+#### FindOne()
+
 ```go
-list := jsonquery.Find(doc, "store/book/*/author")
-// or equal to
-list := jsonquery.Find(doc, "//author")
-// or by QueryAll()
-nodes, err := jsonquery.QueryAll(doc, "//a")
+n := jsonquery.FindOne(doc,"//a")
 ```
 
-#### Find the third book.
+#### Find()
 
 ```go
-book := jsonquery.Find(doc, "//book/*[3]")
+list := jsonquery.Find(doc,"//a")
 ```
 
-#### Find the last book.
+#### QuerySelector()
 
 ```go
-book := jsonquery.Find(doc, "//book/*[last()]")
+n := jsonquery.QuerySelector(doc, xpath.MustCompile("//a"))
 ```
 
-#### Find all books that have an isbn number.
+#### QuerySelectorAll()
 
 ```go
-list := jsonquery.Find(doc, "//book/*[isbn]")
+list :=jsonquery.QuerySelectorAll(doc, xpath.MustCompile("//a"))
 ```
 
-#### Find all books priced less than 10.
+#### Query()
 
 ```go
-list := jsonquery.Find(doc, "//book/*[price<10]")
+n, err := jsonquery.Query(doc, "*")
 ```
 
-Examples
-===
+#### QueryAll()
 
 ```go
-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())
-}
+list, err := jsonquery.QueryAll(doc, "*")
+```
+
+#### Query() vs FindOne()
+
+- `Query()` will return an error if give xpath query expr is not valid.
+
+- `FindOne` will panic error and interrupt your program if give xpath query expr is not valid.
+
+#### OutputXML()
+
+Convert current JSON object to XML format.
+
+# Examples
+
+```json
+{
+"store": {
+"book": [
+{
+"id": 1,
+"category": "reference",
+"author": "Nigel Rees",
+"title": "Sayings of the Century",
+"price": 8.95
+},
+{
+"id": 2,
+"category": "fiction",
+"author": "Evelyn Waugh",
+"title": "Sword of Honour",
+"price": 12.99
+},
+{
+"id": 3,
+"category": "fiction",
+"author": "Herman Melville",
+"title": "Moby Dick",
+"isbn": "0-553-21311-3",
+"price": 8.99
+},
+{
+"id": 4,
+"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
 }
+
 ```
+
+#### Tests
+
+| Query | Matched | Native Value Types | Native Values |
+| ------- | -------------| -------- | -------------|
+| `//book` | 1 | []interface{} | `{"book": [{"id":1,... }, {"id":2,... }, {"id":3,... }, {"id":4,... }]}` |
+| `//book/*` | 4 | [map[string]interface{}] |`{"id":1,... }`, `{"id":2,... }`, `{"id":3,... }`, `{"id":4,... }` |
+| `//*[price<12.99]` | 2 | slice, [map[string]interface{}] | `{"id":1,...}`, `{"id":3,...}` |
+| `//book/*/author` | 4 | []string | `{"author": "Nigel Rees"}`, `{"author": "Evelyn Waugh"}`, `{"author": "Herman Melville"}`, `{"author": "J. R. R. Tolkien"}` |
+| `//book/*[last()]` | 1 | map[string]interface {} | `{"id":4,...}` |
+| `//book/*[1]` | 1 | map[string]interface {} | `{"id":1,...}` |
+| `//book/*[2]` | 1 | map[string]interface{} | `{"id":2,...}` |
+| `//*[isbn]` | 2 | [map[string]interface{}] | `{"id":3,"isbn":"0-553-21311-3",...}`,`{"id":4,"isbn":"0-395-19395-8",...}` |
+| `//*[isbn='0-553-21311-3']` | 1 | object, map[string]interface{} | `{"id":3,"isbn":"0-553-21311-3",...}` |
+| `//bicycle` | 1 | object, map[string]interface {} | `{"bicycle":{"color":...,}}` |
+| `//bicycle/color[text()='red']` | 1 | map[string]interface {} | `{"color":"red"}` |
+| `//*/category[contains(.,'refer')]` | 1 | string | `{"category": "reference"}` |
+| `//price[.=22.99]` | 1 | float64 | `{"price": 22.99}` |
+| `//expensive/text()` | 1 | string | `10` |
+
+For more supports XPath feature and function see https://.com/antchfx/xpath