router/context.go

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package router
import (
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"bytes"
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"encoding/json"
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"io"
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"net/http"
"github.com/julienschmidt/httprouter"
)
// Context is passed to handlers and middlewares
type Context struct {
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router *Router
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Request *http.Request
Response http.ResponseWriter
Param func(string) string
store map[string]interface{}
}
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func newContext(router *Router, res http.ResponseWriter, req *http.Request, param httprouter.Params) *Context {
return &Context{router, req, res, param.ByName, make(map[string]interface{})}
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}
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// QueryParam returns the specified parameter from the query string.
// Returns an empty string if it doesn't exist. Returns the first parameter if multiple instances exist
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func (c *Context) QueryParam(param string) string {
params := c.Request.URL.Query()[param]
if params == nil {
return ``
}
return params[0]
}
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// Redirect sends a redirect to the client
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func (c *Context) Redirect(code int, url string) error {
http.Redirect(c.Response, c.Request, url, code)
return nil
}
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// Bytes returns the given status code and writes the bytes to the body
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func (c *Context) Bytes(code int, b []byte) error {
c.Response.WriteHeader(code)
_, err := c.Response.Write(b)
return err
}
// String returns the given status code and writes the string to the body
func (c *Context) String(code int, s string) error {
c.Response.Header().Set(`Content-Type`, `text/plain`)
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c.Response.WriteHeader(code)
_, err := c.Response.Write([]byte(s))
return err
}
// StatusText returns the given status code with the matching status text
func (c *Context) StatusText(code int) error {
return c.String(code, http.StatusText(code))
}
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// NoContent returns the given status code without writing anything to the body
func (c *Context) NoContent(code int) error {
c.Response.WriteHeader(code)
return nil
}
// JSON returns the given status code and writes JSON to the body
func (c *Context) JSON(code int, data interface{}) error {
c.Response.Header().Set(`Content-Type`, `application/json`)
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c.Response.WriteHeader(code)
return json.NewEncoder(c.Response).Encode(data) // TODO: Encode to buffer first to prevent partial responses on error
}
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// Render renders a templating using the Renderer set in router
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func (c *Context) Render(code int, template string, data interface{}) error {
if c.router.Renderer == nil {
panic(`Cannot call render without a renderer set`)
}
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var b bytes.Buffer
err := c.router.Renderer.Render(&b, template, data, c)
if err != nil {
return err
}
c.Response.Header().Set(`Content-Type`, `text/html`)
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c.Response.WriteHeader(code)
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_, _ = io.Copy(c.Response, &b)
return nil
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}
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// Set sets a value in the context. Set is not safe to be used concurrently
func (c *Context) Set(key string, value interface{}) {
c.store[key] = value
}
// Get retrieves a value from the context.
func (c *Context) Get(key string) interface{} {
return c.store[key]
}