Merge pull request #19 from segmentio/add-data-manipulation

Add mod tag an allow modification of the data

load.go

@@ -2,6 +2,7 @@ package conf
 
 import (
  "bytes"
+ "context"
  "errors"
  "flag"
  "fmt"
@@ -12,13 +13,22 @@ import (
  "sort"
  "strings"
 
+ "gopkg.in/go-playground/mold.v2/modifiers"
+
  validator "gopkg.in/validator.v2"
 
  // Load all default adapters of the objconv package.
  _ "github.com/segmentio/objconv/adapters"
  "github.com/segmentio/objconv/yaml"
 )
 
+var (
+ // Modifier is the default modification lib using the "mod" tag; it is
+ // exposed to allow registering of custom modifiers and aliases or to
+ // be set to a more central instance located in another repo.
+ Modifier = modifiers.New()
+)
+
 // Load the program's configuration into cfg, and returns the list of leftover
 // arguments.
 //
@@ -139,6 +149,10 @@ func (ld Loader) Load(cfg interface{}) (cmd string, args []string, err error) {
  return
  }
 
+ if err = Modifier.Struct(context.Background(), cfg); err != nil {
+ return
+ }
+
  if err = validator.Validate(v.Interface()); err != nil {
  err = makeValidationError(err, v.Type())
  }

load_test.go

@@ -407,6 +407,22 @@ func TestValidator(t *testing.T) {
  }
 }
 
+func TestModifiers(t *testing.T) {
+ config := struct {
+ Email string `conf:"email" validate:"nonzero" mod:"trim,lcase"`
+ }{
+ Email: " [email protected]",
+ }
+
+ _, _, err := (Loader{}).Load(&config)
+ if err != nil {
+ t.Error("bad error:", err)
+ }
+ if config.Email != "[email protected]" {
+ t.Error("bad mod value:", config.Email)
+ }
+}
+
 func parseURL(s string) url.URL {
  u, _ := url.Parse(s)
  return *u