Response Handling

Response Types

Lemmego’s Context provides several response methods.

JSON

func MyHandler(c app.Context) error {
    return c.JSON(app.M{
        "id":    1,
        "name":  "John",
        "email": "john@example.com",
    })
}

HTML

func MyHandler(c app.Context) error {
    return c.HTML([]byte("<h1>Hello</h1>"))
}

Text

func MyHandler(c app.Context) error {
    return c.Text([]byte("Hello, World!"))
}

XML

Return XML responses from structs, maps, or raw strings:

// From a map
func MyHandler(c app.Context) error {
    return c.XML(app.M{
        "status": "ok",
        "count":  42,
    })
}
// Produces: <response><status>ok</status><count>42</count></response>

// From a struct
type Item struct {
    XMLName xml.Name `xml:"item"`
    ID      int      `xml:"id"`
    Name    string   `xml:"name"`
}

func MyHandler(c app.Context) error {
    return c.XML(Item{ID: 1, Name: "test"})
}
// Produces: <item><id>1</id><name>test</name></item>

// From a raw string or bytes
func MyHandler(c app.Context) error {
    return c.XML("<status>ok</status>")
}

Combine with content negotiation:

if c.WantsXML() {
    return c.XML(data)
}
return c.JSON(data)

Redirect

func MyHandler(c app.Context) error {
    return c.Redirect("/dashboard")
}

func MyHandler(c app.Context) error {
    return c.Back() // redirect to referrer
}

File Responses

// Serve a file from the filesystem
func MyHandler(c app.Context) error {
    return c.File("path/to/file.pdf")
}

// Serve a file from a storage disk
func MyHandler(c app.Context) error {
    return c.StorageFile("uploads/report.pdf")
}

// Download a file with a custom filename
func MyHandler(c app.Context) error {
    return c.Download("path/to/file.pdf", "report.pdf")
}

Template Rendering

Go Templates

Render Go HTML templates using the res package:

import "github.com/lemmego/api/res"

func MyHandler(c app.Context) error {
    tmpl := res.NewTemplate(c, "index.page.gohtml")
    tmpl = tmpl.WithData(map[string]any{
        "title": "Hello World",
    })
    return c.Render(tmpl)
}

Templates follow naming conventions:

*.page.gohtml — page templates
*.layout.gohtml — layout templates
*.partial.gohtml — partial/reusable templates

The template engine automatically discovers layouts and partials in parent directories.

Templ

Render Templ components using the templ package:

import "github.com/lemmego/templ"

func MyHandler(c app.Context) error {
    return c.Templ(components.Hello("World"))
}

Alternatively:

return templ.Respond(c, components.Hello("World"))

Inertia

For Inertia.js responses:

import "github.com/lemmego/inertia"

func MyHandler(c app.Context) error {
    return inertia.Respond(c, "Users/Index", inertia.Props{
        "users": users,
    })
}

Status Codes

Set custom HTTP status codes:

func MyHandler(c app.Context) error {
    c.SetStatus(http.StatusCreated)
    return c.JSON(app.M{"id": 1})
}

Setting Headers

func MyHandler(c app.Context) error {
    c.SetHeader("X-Custom", "value")
    c.SetHeader("Cache-Control", "no-cache")
    return c.JSON(app.M{"ok": true})
}

Response Status Helpers

c.NoContent()           // 204
c.Error(status, err)    // Custom error with status

Request Handling Error Handling