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load_struct.go
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/
load_struct.go
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package dotenv
import (
"fmt"
"os"
"reflect"
"strconv"
)
func LoadStruct(data interface{}) error {
dataType := reflect.TypeOf(data)
dataValue := reflect.ValueOf(data)
if dataType.Kind() != reflect.Ptr || dataValue.IsNil() {
return fmt.Errorf("data must be a pointer to a struct")
}
dataType = dataType.Elem()
dataValue = dataValue.Elem()
return parseFields(dataType, dataValue)
}
func parseFields(dataType reflect.Type, dataValue reflect.Value) error {
for i := 0; i < dataType.NumField(); i++ {
field := dataType.Field(i)
value := dataValue.Field(i)
if value.Kind() == reflect.Struct {
if err := parseFields(field.Type, value); err != nil {
return err
}
continue
}
envTag := field.Tag.Get("env")
if envTag == "" {
continue
}
envValue, found := os.LookupEnv(envTag)
if !found {
continue
}
switch value.Kind() {
case reflect.String:
value.SetString(envValue)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
intVal, err := strconv.ParseInt(envValue, 10, 64)
if err != nil {
return fmt.Errorf("failed to parse int field %s: %s", field.Name, err)
}
value.SetInt(intVal)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
uintVal, err := strconv.ParseUint(envValue, 10, 64)
if err != nil {
return fmt.Errorf("failed to parse uint field %s: %s", field.Name, err)
}
value.SetUint(uintVal)
case reflect.Bool:
boolVal, err := strconv.ParseBool(envValue)
if err != nil {
return fmt.Errorf("failed to parse bool field %s: %s", field.Name, err)
}
value.SetBool(boolVal)
case reflect.Float32, reflect.Float64:
floatVal, err := strconv.ParseFloat(envValue, 64)
if err != nil {
return fmt.Errorf("failed to parse float field %s: %s", field.Name, err)
}
value.SetFloat(floatVal)
default:
return fmt.Errorf("unsupported type for field %s", field.Name)
}
}
return nil
}