deal with the previous changes

2 files changed, 9 insertions, 3 deletions

diff --git a/entity/id.go b/entity/id.go
index 1b78aacd..08916987 100644
--- a/entity/id.go
+++ b/entity/id.go
@@ -8,8 +8,8 @@ import (
 	"github.com/pkg/errors"
 )
 
-const IdLengthSHA1 = 40
-const IdLengthSHA256 = 64
+// sha-256
+const idLength = 64
 const humanIdLength = 7
 
 const UnsetId = Id("unset")
@@ -55,7 +55,7 @@ func (i Id) MarshalGQL(w io.Writer) {
 
 // IsValid tell if the Id is valid
 func (i Id) Validate() error {
-	if len(i) != IdLengthSHA1 && len(i) != IdLengthSHA256 {
+	if len(i) != idLength {
 		return fmt.Errorf("invalid length")
 	}
 	for _, r := range i {
diff --git a/entity/interface.go b/entity/interface.go
index dd5d69b1..fb4735e4 100644
--- a/entity/interface.go
+++ b/entity/interface.go
@@ -2,5 +2,11 @@ package entity
 
 type Interface interface {
 	// Id return the Entity identifier
+	//
+	// This Id need to be immutable without having to store the entity somewhere (ie, an entity only in memory
+	// should have a valid Id, and it should not change if further edit are done on this entity).
+	// How to achieve that is up to the entity itself. A common way would be to take a hash of an immutable data at
+	// the root of the entity.
+	// It is acceptable to use such a hash and keep mutating that data as long as Id() is not called.
 	Id() Id
 }