v0.3.0
, the package requires Go 1.17+, due to the usage of new additions to the reflect package.
package main
import "json"
import "github.com/simonnilsson/ask"
func main() {
// Use parsed JSON as source data
var object map[string]interface{}
json.Unmarshal([]byte(`{ "a": [{ "b": { "c": 3 } }] }`), &object)
// Extract the 3
res, ok := ask.For(object, "a[0].b.c").Int(0)
fmt.Println(res, ok)
// Output: 3 true
// Attempt extracting a string at path .d that does not exist
res2, ok := ask.For(object, "a[0].b.d").String("nothing")
fmt.Println(res2, ok)
// Output: nothing false
}
Internally ask uses type assertions to traverse down the path supplied. Each invocation starts by calling For() with your data structure source and the path in this structure to extract.
For(source interface{}, path string) *Answer
Additional paths can be traversed by calling Path() on the resulting answer.
(a *Answer) Path(path string) *Answer
After receiving an *Answer
from a call to For() it can be asserted to a type. The methods for this is seen below. Each function takes a default value as a parameter that will be returned in case the value can not be asserted from the answer. A second return value is used to indicate if the assertion was successful.
String(d string) (string, bool)
Bool(d bool) (bool, bool)
Int(d int64) (int64, bool)
Uint(d uint64) (uint64, bool)
Float(d float64) (float64, bool)
Slice(d []interface{}) ([]interface{}, bool)
Map(d map[string]interface{}) (map[string]interface{}, bool)
If a number is found but it is of different type than requested it will be casted to desired type and return success. If the value would not fit within the valid range of requested type the operation will fail however and the default parameter will be returned instead.
Two additional methods are available, one to check if the answer has a value (not nil) and one to return the raw value as a interface{}.
Exists() bool
Value() interface{}
For full documentation see pkg.go.dev.