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Gin Web Framework

Query string parameters

Query string parameters are the key-value pairs that appear after the ? in a URL (for example, /search?q=gin&page=2). Gin provides two methods to read them:

  • c.Query("key") returns the value of the query parameter, or an empty string if the key is not present.
  • c.DefaultQuery("key", "default") returns the value, or the specified default value if the key is not present.

Both methods are shortcuts for accessing c.Request.URL.Query() with less boilerplate.

package main


import (
  "net/http"


  "github.com/gin-gonic/gin"
)


func main() {
  router := gin.Default()


  // Query string parameters are parsed using the existing underlying request object.
  // The request responds to a url matching:  /welcome?firstname=Jane&lastname=Doe
  router.GET("/welcome", func(c *gin.Context) {
    firstname := c.DefaultQuery("firstname", "Guest")
    lastname := c.Query("lastname") // shortcut for c.Request.URL.Query().Get("lastname")


    c.String(http.StatusOK, "Hello %s %s", firstname, lastname)
  })
  router.Run(":8080")
}

Test it

Terminal window
# Both parameters provided
curl "http://localhost:8080/welcome?firstname=Jane&lastname=Doe"
# Output: Hello Jane Doe


# Missing firstname -- uses default value "Guest"
curl "http://localhost:8080/welcome?lastname=Doe"
# Output: Hello Guest Doe


# No parameters at all
curl "http://localhost:8080/welcome"
# Output: Hello Guest

See also