Package jsonpath
Package jsonpath is an implementation of http://goessner.net/articles/JsonPath/
If a JSONPath contains one of
[key1, key2 ...], .., *, [min:max], [min:max:step], (? expression)
all matchs are listed in an []interface{}
The package comes with an extension of JSONPath to access the wildcard values of a match.
If the JSONPath is used inside of a JSON object, you can use placeholder '#' or '#i' with natural number i
to access all wildcards values or the ith wildcard
This package can be extended with gval modules for script features like multiply, length, regex or many more.
So take a look at github.com/PaesslerAG/gval.
▾ Example (Gval)
Code:
builder := gval.Full(jsonpath.PlaceholderExtension())
path, err := builder.NewEvaluable("{#1: $..[?@.ping && @.speed > 100].name}")
if err != nil {
fmt.Println(err)
os.Exit(1)
}
v := interface{}(nil)
err = json.Unmarshal([]byte(`{
"device 1":{
"name": "fancy device",
"ping": true,
"speed": 200,
"subdevice 1":{
"ping" : true,
"speed" : 99,
"name" : "boring subdevice"
},
"subdevice 2":{
"ping" : true,
"speed" : 150,
"name" : "fancy subdevice"
},
"not an device":{
"name" : "ping me but I have no speed property",
"ping" : true
}
},
"fictive device":{
"ping" : false,
"speed" : 1000,
"name" : "dream device"
}
}`), &v)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
devices, err := path(context.Background(), v)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
for device, name := range devices.(map[string]interface{}) {
fmt.Printf("%s -> %v\n", device, name)
}
Output:
device 1 -> fancy device
subdevice 2 -> fancy subdevice
func Get(path string, value interface{}) (interface{}, error)
Get executes given JSONPath on given value
▾ Example
Code:
v := interface{}(nil)
json.Unmarshal([]byte(`{
"welcome":{
"message":["Good Morning", "Hello World!"]
}
}`), &v)
welcome, err := jsonpath.Get("$.welcome.message[1]", v)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
fmt.Println(welcome)
Output:
Hello World!
▾ Example (Filter)
Code:
v := interface{}(nil)
json.Unmarshal([]byte(`[
{"key":"a","value" : "I"},
{"key":"b","value" : "II"},
{"key":"c","value" : "III"}
]`), &v)
values, err := jsonpath.Get(`$[? @.key=="b"].value`, v)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
for _, value := range values.([]interface{}) {
fmt.Println(value)
}
Output:
II
▾ Example (Wildcard)
Code:
v := interface{}(nil)
json.Unmarshal([]byte(`{
"welcome":{
"message":["Good Morning", "Hello World!"]
}
}`), &v)
welcome, err := jsonpath.Get("$.welcome.message[*]", v)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
for _, value := range welcome.([]interface{}) {
fmt.Printf("%v\n", value)
}
Output:
Good Morning
Hello World!
func Language() gval.Language
Language is the JSONPath Language
func New(path string) (gval.Evaluable, error)
New returns an selector for given JSONPath
func PlaceholderExtension() gval.Language
PlaceholderExtension is the JSONPath Language with placeholder