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This example shows how to utilize the Go programming language to write an HTTP server. It implements methods for create, read, update and delete on a map of people. The data is stored in-memory and is therefore lost after stopping the server.
Start the server (from src directory)
go run http_srv.go
The following commands show how to interface with the server using the popular cURL program. Open another terminal instance to execute these commands.
Create a new person
curl -X POST http://localhost:8080/people/create \
-H "Content-Type: application/x-www-form-urlencoded" \
-d 'first_name=John&last_name=Doe'
### Output: created
When this command is executed, a new person gets stored in the people map.
The attributes fo the person, namely firstname and lastname, are specified in the POST body
URL-encoded. In this example John Doe is used.
The following snippet is responsible for creating new a ner person.
func createPerson(w http.ResponseWriter, r *http.Request) {
if r.Method == "POST" {
fn := r.FormValue("first_name")
ln := r.FormValue("last_name")
p := Person{
FirstName: fn,
LastName: ln,
}
people[lastId] = p
lastId++
w.WriteHeader(http.StatusCreated)
w.Write([]byte("created"))
} else {
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte("bad request"))
}
}
List all people
curl http://localhost:8080/people
### Output: {"0":{"first_name":"John","last_name":"Doe"}}
This command calls the readPeople() function.
It returns all the people currently stored in the data map in a JSON format.
func readPeople(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
err := json.NewEncoder(w).Encode(people)
if err != nil {
log.Println(err)
}
}
Update a person
When updating a person, an identifying key must be specified. for this we just use an incrementing integer value starting at zero. This key can be found in the output from the list function. For the first person inserted, this is (of course) 0.
curl -X PUT http://localhost:8080/people/update?id=0 \
-H "Content-Type: application/x-www-form-urlencoded" \
-d 'first_name=Alice&last_name=Smith'
### Output: updated
func updatePerson(w http.ResponseWriter, r *http.Request) {
id := r.FormValue("id")
intId, err := strconv.Atoi(id)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte("bad request"))
return
}
person, ok := people[intId]
if !ok {
w.WriteHeader(http.StatusNotFound)
w.Write([]byte("not found"))
return
}
person.FirstName = r.FormValue("first_name")
person.LastName = r.FormValue("last_name")
people[intId] = person
w.WriteHeader(http.StatusAccepted)
w.Write([]byte("updated"))
}
Now check again the list function
curl http://localhost:8080/people
### Output: {"0":{"first_name":"Alice","last_name":"Smith"}}
Delete a person
Deleting the only person in the map by calling the following HTTP endpoint with the ID 0.
curl -X DELETE http://localhost:8080/people/delete?id=0
### Output: deleted
func deletePerson(w http.ResponseWriter, r *http.Request) {
if r.Method == "DELETE" {
id := r.FormValue("id")
idInt, err := strconv.Atoi(id)
if err != nil {
log.Println(err)
}
_, ok := people[idInt]
if !ok {
w.WriteHeader(http.StatusNotFound)
return
}
delete(people, idInt)
w.WriteHeader(http.StatusOK)
w.Write([]byte("deleted"))
} else {
w.Write([]byte("bad request"))
}
}
The people map should now be empty.
Check this by calling the list function again
curl http://localhost:8080/people
### Output: {}
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