From ea42a7b2e44bb7ee56ae09f582db99ec75da298c Mon Sep 17 00:00:00 2001
From: EwenQuim <ewen.quimerch@gmail.com>
Date: Mon, 8 Jul 2024 11:06:30 +0200
Subject: [PATCH] Better transformation guide

---
 documentation/docs/guides/transformation.mdx | 39 +++++++++++++++++++-
 documentation/src/components/FlowChart.js    |  1 +
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/documentation/docs/guides/transformation.mdx b/documentation/docs/guides/transformation.mdx
index 6787aeac..95d6077e 100644
--- a/documentation/docs/guides/transformation.mdx
+++ b/documentation/docs/guides/transformation.mdx
@@ -42,7 +42,7 @@ In the example above, we have a `User` struct with two fields: `FirstName` and `
 When using the following controller, the data will be transformed before it is unmarshaled into the `User` struct.
 
 ```go
-func myController(c fuego.ContextWithBody[User]) (User, error) {
+func echoCapitalized(c fuego.ContextWithBody[User]) (User, error) {
 	user, err := c.Body()
 	if err != nil {
 		return User{}, err
@@ -53,3 +53,40 @@ func myController(c fuego.ContextWithBody[User]) (User, error) {
 	return u, nil
 }
 ```
+
+## Recursion
+
+Transformation is not recursive. If you have nested structs, you will need to transform each struct individually. This is done on purpose to give you more control over the transformation process.
+
+```go
+type Address struct {
+	Street string `json:"street"`
+	City   string `json:"city"`
+}
+
+func (a *Address) InTransform(ctx context.Context) error {
+	a.Street = strings.TrimSpace(a.Street)
+	a.City = strings.ToUpper(a.City)
+	return nil
+}
+
+type User struct {
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+	// highlight-next-line
+	Address   Address `json:"address"` // Nested struct
+}
+
+func (u *User) InTransform(ctx context.Context) error {
+	u.FirstName = strings.ToUpper(u.FirstName)
+	u.LastName = strings.TrimSpace(u.LastName)
+
+// highlight-next-line
+	err := u.Address.InTransform(ctx) // Transform the nested struct
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+```
diff --git a/documentation/src/components/FlowChart.js b/documentation/src/components/FlowChart.js
index 82efb16f..c05a9fd1 100644
--- a/documentation/src/components/FlowChart.js
+++ b/documentation/src/components/FlowChart.js
@@ -32,6 +32,7 @@ subgraph fuego
  click ErrorHandler "/fuego/docs/guides/errors" "Error Handling"
 end
 
+ErrorHandler -- JSON{b:'Error!'} --> resp(Response)
 Serialization -- JSON{b:'My Response!'} --> resp(Response)
 Controller -. JSON{b:'Custom Response!'} .-> resp(Response)