Cover Page

Backend Page

Go with Echo

handlers.go

Change to your chatterd folder and edit handlers.go:

server$ cd ~/reactive/chatterd
server$ vi handlers.go

Add one new property to the Chatt struct:

type Chatt struct {
    // . . .
    Audio  *string    `json:"audio"`
}

To the back-end database, audio is just a string. Since the audio string optional, we set the type to *string, which can take a null pointer, nil in Go.

To handle audio data uploads, make a copy of your postchatt() function inside your handlers.go file and name the copy postaudio(). Replace the call to chatterDB.Exec() with:

	_, err := chatterDB.Exec(background, `INSERT INTO chatts (username, message, id, audio) VALUES ($1, $2, gen_random_uuid(), $3)`, chatt.Username, chatt.Message, chatt.Audio)

which extracts the audio entry from the JSON object and insert it into the chatts table, along with the rest of its associated chatt.

Next, make a copy of your getchatts() function inside your handlers.go file and name the copy getaudio(). Replace the SELECT statement with: SELECT username, message, id, time, audio FROM chatts. This will retrieve all data, including our new audio string from the PostgreSQL database.

Still in getaudio(), replace the rows.Scan() call in the for rows.Next() {} block with:

		err = rows.Scan(&chatt.Username, &chatt.Message, &chatt.Id, &chatt.Timestamp, &chatt.Audio)

and if the returned err is nil:

        chattArr = append(chattArr, []any{chatt.Username, chatt.Message, chatt.Id, chatt.Timestamp, chatt.Audio})

In addition to the original columns, we added reading the audio column and included it in the chatt data returned to the front end.

We’re done with handlers.go. Save and exit the file.

main.go

Edit the file main.go:

server$ vi main.go

Find the global variable router and add the following new routes for the new APIs /getaudio and /postaudio:

    {"GET", "/getaudio/", getaudio},
    {"POST", "/postaudio/", postaudio},

We’re done with main.go. Save and exit the file.

Build and test run

To build your server:

server$ go build

Go is a compiled language, like C/C++ and unlike Python, which is an interpreted language. This means you must run go build each and every time you made changes to your code, for the changes to show up in your executable.

To run your server:

server$ sudo ./chatterd
# Hit ^C to end the test

The cover backend spec provides instructions for Testing audio upload.