update a command through the api

cmd/api/command.go

@@ -73,6 +73,71 @@ func (app *application) createCommandHandler(w http.ResponseWriter, r *http.Requ
 	}
 }
 
+func (app *application) updateCommandHandler(w http.ResponseWriter, r *http.Request) {
+	name, err := app.readCommandNameParam(r)
+	if err != nil {
+		app.notFoundResponse(w, r)
+		return
+	}
+
+	command, err := app.Models.Commands.Get(name)
+	if err != nil {
+		switch {
+		case errors.Is(err, data.ErrRecordNotFound):
+			app.notFoundResponse(w, r)
+		default:
+			app.serverErrorResponse(w, r, err)
+		}
+		return
+	}
+
+	var input struct {
+		Name     *string `json:"name"`
+		Text     *string `json:"text"`
+		Category *string `json:"category"`
+		Level    *int    `json:"level"`
+	}
+
+	err = app.readJSON(w, r, &input)
+	if err != nil {
+		app.badRequestResponse(w, r, err)
+		return
+	}
+
+	// There is a name since we successfully queried the database for
+	// a command, so no need to check != nil.
+	command.Name = *input.Name
+
+	if input.Text != nil {
+		command.Text = *input.Text
+	}
+
+	if input.Category != nil {
+		command.Category = *input.Category
+	}
+
+	if input.Level != nil {
+		command.Level = *input.Level
+	}
+
+	err = app.Models.Commands.Update(command)
+	if err != nil {
+		switch {
+		case errors.Is(err, data.ErrEditConflict):
+			app.editConflictResponse(w, r)
+		default:
+			app.serverErrorResponse(w, r, err)
+		}
+		return
+	}
+
+	err = app.writeJSON(w, http.StatusOK, envelope{"command": command}, nil)
+	if err != nil {
+		app.serverErrorResponse(w, r, err)
+	}
+
+}
+
 func (app *application) deleteCommandHandler(w http.ResponseWriter, r *http.Request) {
 	name, err := app.readCommandNameParam(r)
 	if err != nil {

cmd/api/errors.go

@@ -38,3 +38,8 @@ func (app *application) notFoundResponse(w http.ResponseWriter, r *http.Request)
 	message := "the requested resource could not be found"
 	app.errorResponse(w, r, http.StatusNotFound, message)
 }
+
+func (app *application) editConflictResponse(w http.ResponseWriter, r *http.Request) {
+	message := "unable to update the record due to an edit conflict, please try again"
+	app.errorResponse(w, r, http.StatusConflict, message)
+}

cmd/api/routes.go

@@ -11,6 +11,7 @@ func (app *application) routes() *httprouter.Router {
 
 	router.HandlerFunc(http.MethodGet, "/v1/commands/:name", app.showCommandHandler)
 	router.HandlerFunc(http.MethodPost, "/v1/commands", app.createCommandHandler)
+	router.HandlerFunc(http.MethodPatch, "/v1/commands/:name", app.updateCommandHandler)
 	router.HandlerFunc(http.MethodDelete, "/v1/commands/:name", app.deleteCommandHandler)
 	return router
 }

internal/data/commands.go

@@ -8,9 +8,9 @@ import (
 type Command struct {
 	ID       int    `json:"id"`
 	Name     string `json:"name"`
-	Text     string `json:"text"`
-	Category string `json:"category"`
-	Level    int    `json:"level"`
+	Text     string `json:"text,omitempty"`
+	Category string `json:"category,omitempty"`
+	Level    int    `json:"level,omitempty"`
 }
 
 type CommandModel struct {
@@ -46,6 +46,33 @@ func (c CommandModel) Get(name string) (*Command, error) {
 	return &command, nil
 }
 
+func (c CommandModel) Update(command *Command) error {
+	query := `
+	UPDATE commands
+	SET text = $2, category = $3, level = $4
+	WHERE name = $1
+	RETURNING id`
+
+	args := []interface{}{
+		command.Name,
+		command.Text,
+		command.Category,
+		command.Level,
+	}
+
+	err := c.DB.QueryRow(query, args...).Scan(&command.ID)
+	if err != nil {
+		switch {
+		case errors.Is(err, sql.ErrNoRows):
+			return ErrEditConflict
+		default:
+			return err
+		}
+	}
+
+	return nil
+}
+
 // SetCategory queries the database for an entry with the provided name,
 // if there is one it updates the categories level with the provided level.
 func (c CommandModel) SetCategory(name string, category string) error {

internal/data/models.go

@@ -8,6 +8,7 @@ import (
 var (
 	ErrRecordNotFound             = errors.New("record not found")
 	ErrChannelRecordAlreadyExists = errors.New("channel already in database")
+	ErrEditConflict               = errors.New("edit conflict")
 	ErrCommandRecordAlreadyExists = errors.New("command already exists")
 	ErrUserAlreadyExists          = errors.New("user already in database")
 )
@@ -31,6 +32,7 @@ type Models struct {
 	Commands interface {
 		Get(name string) (*Command, error)
 		Insert(command *Command) error
+		Update(command *Command) error
 		SetLevel(name string, level int) error
 		SetCategory(name, category string) error
 		Delete(name string) error