booking2/

README

Hotel Bookings

This is a clone of the booking application that uses the pongo2 and ace engines The Booking sample app demonstrates (browse the source):

• Using an SQL (SQLite) database and configuring the Revel DB module.

• Using the third party GORP ORM-ish library

• Interceptors for checking that an user is logged in.

• Using validation and displaying inline errors

  booking/app/ models # Structs and validation. booking.go hotel.go user.go

    controllers
    	init.go    # Register all of the interceptors.
    	gorp.go    # A plugin for setting up Gorp, creating tables, and managing transactions.
    	app.go     # "Login" and "Register new user" pages
    	hotels.go  # Hotel searching and booking
  
    views
    	...
  

sqlite Installation

The booking app uses go-sqlite3 database driver (which wraps the native C library).

To install on OSX:

1. Install Homebrew if you don't already have it.
2. Install pkg-config and sqlite3:

$ brew install pkgconfig sqlite3

To install on Ubuntu:

$ sudo apt-get install sqlite3 libsqlite3-dev

Once you have SQLite installed, it will be possible to run the booking app:

$ revel run github.com/revel/samples/booking

Database / Gorp Plugin

app/controllers/gorp.go defines GorpPlugin, which is a plugin that does a couple things:

• OnAppStart: Uses the DB module to open a SQLite in-memory database, create the User, Booking, and Hotel tables, and insert some test records.
• BeforeRequest: Begins a transaction and stores the Transaction on the Controller
• AfterRequest: Commits the transaction. Panics if there was an error.
• OnException: Rolls back the transaction.

Interceptors

app/controllers/init.go registers the interceptors that run before every action:

{% highlight go %} func init() { revel.OnAppStart(Init) revel.InterceptMethod((*GorpController).Begin, revel.BEFORE) revel.InterceptMethod(Application.AddUser, revel.BEFORE) revel.InterceptMethod(Hotels.checkUser, revel.BEFORE) revel.InterceptMethod((*GorpController).Commit, revel.AFTER) revel.InterceptMethod((*GorpController).Rollback, revel.FINALLY) } {% endhighlight %}

As an example, checkUser looks up the username in the session and redirects the user to log in if they are not already.

{% highlight go %} func (c Hotels) checkUser() revel.Result { if user := c.connected(); user == nil { c.Flash.Error("Please log in first") return c.Redirect(Application.Index) } return nil } {% endhighlight %}

Check out the user management code in app.go

Validation

The booking app does quite a bit of validation.

For example, here is the routine to validate a booking, from models/booking.go:

{% highlight go %} func (booking Booking) Validate(v *revel.Validation) { v.Required(booking.User) v.Required(booking.Hotel) v.Required(booking.CheckInDate) v.Required(booking.CheckOutDate)

v.Match(b.CardNumber, regexp.MustCompile(`\d{16}`)).
	Message("Credit card number must be numeric and 16 digits")

v.Check(booking.NameOnCard,
	revel.Required{},
	revel.MinSize{3},
	revel.MaxSize{70},
)

} {% endhighlight %}

Revel applies the validation and records errors using the name of the validated variable (unless overridden). For example, booking.CheckInDate is required; if it evaluates to the zero date, Revel stores a ValidationError in the validation context under the key "booking.CheckInDate".

Subsequently, the Hotels/Book.html template can easily access them using the field helper:

{% capture ex %}{% raw %} {{with $field := field "booking.CheckInDate" .}}

Check In Date: * {{$field.Error}} ss

{{end}} {% endraw %}{% endcapture %} {% highlight htmldjango %}{{ex}}{% endhighlight %}

The field template helper looks for errors in the validation context, using the field name as the key.

Developing notes

All examples must be in the root folder, no nesting since the travis scripts operate on a bash script to bulk modify the scripts you can do something like

for file in examples/*/ 
  do 
    echo "$file is a directory"
    cd $file && go mod tidy; 
    cd ../..;
    go mod edit -replace "github.com/revel/revel=<yourlocalpath>" $file/go.mod ; 
  done

Before committing change them back by doing

for file in examples/*/ 
  do 
    echo "$file is a directory"
    cd $file && go mod tidy; 
    cd ../..;
    go mod edit -dropreplace "github.com/revel/revel" $file/go.mod ; 
  done