executing query via middleware - middleware

Question

While using strongloop loopback I want check the database for accesstoken and username existence in every request.
So i am making a middleware code:
module.exports = function() {
return function xAuth(req, res, next) {
console.log(req);
};
};
I have added it to :initial" middleware json
"initial": {
"compression": {},
"cors": {
"params": {
"origin": true,
"credentials": true,
"maxAge": 86400
}
},
"./middleware/trumptAuth": {},
"helmet#xssFilter": {},
"helmet#frameguard": {
"params": [
"deny"
]
},
"helmet#hsts": {
"params": {
"maxAge": 0,
"includeSubdomains": true
}
},
"helmet#hidePoweredBy": {},
"helmet#ieNoOpen": {},
"helmet#noSniff": {},
"helmet#noCache": {
"enabled": false
}
}
i want to execute an sql query here but i have no idea on how can i do that, I probably just need "app" variable access or directly "dataSource" access.
Any help is appreciated.

Answer 1

From the docs, "Using variables in middleware" (https://docs.strongloop.com/display/LB/Defining+middleware#Definingmiddleware-Usingvariablesinvalues), it looks like you can pass any part of the app object using this syntax: ${var}. The datasource property exists under the core app object, so you should be able to pass it in that way.

Answer 2

To access "app" variable from middleware use
app.use(function(req, res, next) {
var app = req.app;
...
});
To access "dataSource" variable from middleware use
app.use(function(req, res, next) {
var dataSource = app.datasources.db;
...
});
To access an specific model from middleware use
app.use(function(req, res, next) {
var app = req.app;
var modelName = app.model.modelName;
...
});
for more methods/sources use this documentation link
https://docs.strongloop.com/display/public/LB/Working+with+LoopBack+objects