JSONQ is XPath inspired JSON processing library for Go. It provides functions for traversing JSON structures and for extracting attributes into Go data structures.
Type-safe getters access JSON structures and return type-checked values.
var v interface{}
err := json.Unmarshal([]byte(`{
"issue": {
"fields": {
"project": {
"name": "Operations"
}
}
}
}`), &v)
if err != nil {
log.Fatal(err)
}
name, err := GetString(v, "issue.fields.project.name")
if err != nil {
log.Fatal(err)
}
fmt.Println(name)
// Output: OperationsThe Context type allows you to select elements from JSON data and
extract values into Go data structures. The basic extraction works by
annotating Go structurs with the jsonq structure tags:
var v interface{}
err := json.Unmarshal([]byte(`{
"issue_event_type_name": "issue_assigned",
"issue": {
"fields": {
"project": {
"name": "Operations"
}
},
"key": "OP-1"
}
}`), &v)
if err != nil {
log.Fatal(err)
}
var issue struct {
Key string `jsonq:"issue.key"`
Name string `jsonq:"issue.fields.project.name"`
EventType string `jsonq:"issue_event_type_name"`
}
err = Ctx(v).Extract(&issue)
if err != nil {
log.Fatal(err)
}
fmt.Printf("key=%s, name=%s, type=%s\n", issue.Key, issue.Name, issue.EventType)
// Output: key=OP-1, name=Operations, type=issue_assignedThe Context.Select() function allows you to filter data based on JSON attributes:
var v interface{}
err := json.Unmarshal([]byte(`{
"issue": {
"changelog": {
"items": [
{
"fieldId": "comment",
"toString": "This is cool!",
"fromString": ""
},
{
"fieldId": "assignee",
"toString": "Veijo Linux",
"fromString": null
}
]
}
}
}`), &v)
if err != nil {
log.Fatal(err)
}
var assign struct {
From string `jsonq:"?fromString"`
To string `jsonq:"?toString"`
}
err = Ctx(v).
Select(`issue.changelog.items[fieldId=="assignee"][0]`).
Extract(&assign)
if err != nil {
log.Fatal(err)
}
fmt.Printf("assign from '%s' to '%s'\n", assign.From, assign.To)
// Output: assign from '' to 'Veijo Linux'Note that if the JSON attribute name is prefixed with question mark, the field is optional.
- Getters:
- Number
- Boolean
- Expressions:
- Comparison: ==, !=, <, > <=, >=
- Parenthesized sub-expressions
- Chaining logical expressions
- Number expressions