How to make synchronous queries with Sequelize on Node.js

Question

I started to stew Node.js not long ago and I am using the division of logic into modules. I have a UserSessionController validates whether the user session is still valid:

module.exports.getUserSession = function ( userToken ) {
    models.UserSession.find( {where : Sequelize.and(
        { token: userToken }, { dataExpira { lte: Date() } }) } ).complete ( function (err, user) {
            if (!!err) {
                console.log('Ocorreu um erro ao buscar a sessão do usuário:', err);
                return null;
            } else {
                return user;
            };
    })
}

but when I try to execute this call from another module, when calling the code goes without receiving Return, because it will only be processed when the query is completed.

usuarioLogado = userSession.getUserSession(token)
if (!!usuarioLogado) { //aqui usuarioLogado está undefined
  //faz a ação
} else {
  res.send(401, "Você deve estar logado para realizar alterações.");
  next();
}

how this call is executed on a webservice REST the response to the WS client occurs before the query is executed in the database.

Is there a way to make a call Javascript is executed in a manner synchronous?

Answer 1

The "beauty" of the Node is in its asynchronicity. Pass two callback functions to getUserSession, thus:

userSession.getUserSession(token, 
    function(err){
        res.send(401, "Você deve estar logado para realizar alterações.");
        next();
    }, 
    function(user){
        // faz alguma coisa com o usuario retornado
    });

And in function:

module.exports.getUserSession = function (userToken, failure, success) {
    models.UserSession
               .find({where : Sequelize.and({token: userToken}, 
                                            {dataExpira : {lte: Date()}})
                      })
               .complete(function (err, user) {
                   if (!!err) {
                      return failure(err);
                   } else {
                      return success(user);
                   };
               });
}    

Since I can’t test, make sure you really need the return before the callbacks call.
Maybe you also want to return the code 403 - Forbidden if the user is not authenticated.