Value of $self->req->json is undef

app.pl

put '/source' => sub {
    my $self   = shift;
    my $schema = $self->schema;

    #my $json = $self->req->body;
    say Dumper( $self->req->json );
    # $VAR1 = undef;
    my $source;

    #my $source = $schema->resultset( 'Source' )->create( $json );
    if ( $source ) {
        $self->res->code( 200 );
        $self->render( json => { source_id => $source->id } );
    }
    else {
        $self->res->code( 422 );
        $self->render( json => { error => "Unable to create source." } );
    }
};


# This is the PUT request
PUT /source.json HTTP/1.1
Host: localhost:3000
Content-Type: application/json
Cache-Control: no-cache
Postman-Token: e2a040fd-0a0d-7c0c-5759-ea4fc949c4fd

{ 
  'name': 'Test name',
  'description': 'Test description',
  'url':         'http://domain.com'
}

# Setup
CORE
  Perl        (v5.18.1, darwin)
  Mojolicious (5.24, Tiger Face)

OPTIONAL
  EV 4.0+                 (not installed)
  IO::Socket::IP 0.20+    (not installed)
  IO::Socket::Socks 0.64+ (not installed)
  IO::Socket::SSL 1.84+   (1.953)