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README
¶
Request binding & validation
Three endpoints, same JSON payload, same 400 envelope on validation failure — different shapes of success path.
| Endpoint | Helper | Success behaviour |
|---|---|---|
POST /users/echo |
server.JSONEcho[CreateUser]() |
Validates the body and echoes the value back. |
POST /users |
server.JSONHandler[In, Out] |
Validates, runs real logic (assigns ID, lowercases email), returns a different type. |
POST /users-manual |
server.BindJSON (manual) |
Same shape as the framework path, but built by hand to show what JSONHandler hides. |
Run
go run ./examples/binding &
curl -s -X POST localhost:8080/users \
-H 'Content-Type: application/json' \
-d '{"name":"Ada","email":"Ada@Example.com","age":36,"role":"admin"}'
curl -s -X POST localhost:8080/users/echo \
-H 'Content-Type: application/json' \
-d '{"name":"Ada","email":"a@b.com","age":36,"role":"admin"}'
Rule of thumb
If your handler is func(_, in) (in, nil), use JSONEcho. The moment you
need to compute, transform, or look anything up, use JSONHandler. Reach
for the manual path only when you need custom headers, streaming, or a
non-JSON response shape.
Documentation
¶
Overview ¶
Example: request binding + validation, three ways.
All three endpoints accept the same JSON payload and produce the same shape of 400 response. They differ in what they do on success:
POST /users/echo — server.JSONEcho[CreateUser](). Validates the
body and echoes the validated value back. No
business logic — useful for webhook acks, dev
stubs, and "did this payload pass validation?"
endpoints.
POST /users — server.JSONHandler. Validates, then runs real
business logic (here: assigns a server-side ID,
lowercases the email) and returns a different
response type.
POST /users-manual — uses the lower-level server.BindJSON and renders
the 400 envelope by hand. Useful when you need
to add headers, stream, or build a custom shape.
Rule of thumb: if your handler would be `func(_, in) (in, nil)`, reach for JSONEcho. The moment you need to compute, transform, or look anything up, reach for JSONHandler.
Try it:
go run ./examples/binding &
curl -s -X POST localhost:8080/users \
-H 'Content-Type: application/json' \
-d '{"name":"Ada","email":"Ada@Example.com","age":36,"role":"admin"}'
curl -s -X POST localhost:8080/users/echo \
-H 'Content-Type: application/json' \
-d '{"name":"Ada","email":"ada@example.com","age":36,"role":"admin"}'
curl -s -X POST localhost:8080/users \
-H 'Content-Type: application/json' \
-d '{"name":"A","email":"nope","age":12,"role":"superuser"}'
Source Files
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