Call a function from different controller in express - node.js

Question

I have a function in questionController
show: function (req, res) {
var id = req.params.id;
questionModel.findOne({_id: id}, function (err, question) {
if (err) {
return res.status(500).json({
message: 'Error when getting question.',
error: err
});
}
if (!question) {
return res.status(404).json({
message: 'No such question'
});
}
//var user = userController.show();
return res.render("questions/question", question);
});
},
And i want to somehow use the function from userController so that i would get the user that posted the question. This is the function i want to use:
show: function (req, res) {
var id = req.params.id;
userModel.findOne({_id: id}, function (err, user) {
if (err) {
return res.status(500).json({
message: 'Error when getting user.',
error: err
});
}
if (!user) {
return res.status(404).json({
message: 'No such user'
});
}
return res.json(user);
});
},
Or is there a better way i can achieve this? I should note, i usually use relationship databases.
Code i wish to achieve (in a more elegant way if possible):
//this is a questionController function
show: function (req, res) {
var id = req.params.id;
questionModel.findOne({_id: id}, function (err, question) {
if (err) {
return res.status(500).json({
message: 'Error when getting question.',
error: err
});
}
if (!question) {
return res.status(404).json({
message: 'No such question'
});
}
var userID = question.userID;
//this is a function i copied from userController that i would like to call from userController so it would be a bit more elegant
userModel.findOne({_id: userID}, function (err, user) {
if (err) {
return res.status(500).json({
message: 'Error when getting user.',
error: err
});
}
if (!user) {
return res.status(404).json({
message: 'No such user'
});
}
question.username = user.username;
return res.render("questions/question", question);
});
});
},

Answer 1

I believe I understood what you want, please, let me know if got it right.
Try this:
Answer: you must use mySchema.methods
In the same file you are defining your User schema, before mongoose.model(...) (i.e., before you compile the model):
UserSchema.methods.doYourThing(id){
//--------------------------------------------------------
//this is just the function you had to copy, and want to use
this.model("User").findOne({_id: id}, function (err, user) {
if (err) {
return res.status(500).json({
message: 'Error when getting user.',
error: err
});
}
if (!user) {
return res.status(404).json({
message: 'No such user'
});
}
return res.json(user);
});
},
}
Then, when you need to use it, you could do something like:
const user= mongoose.model("User")
..........
user.doYourThing(userid);
I have done the code from my head (i.e., I did not test it), and I do not have information about your schema; you will need to fix my typos and/or adapt to your code; I hope you get the idea.
References
Mongoose "this.model is not a function"
https://mongoosejs.com/docs/models.html
https://mongoosejs.com/docs/guide.html#methods

Answer 2

You should try to import the controller and then call the function;
const userController = require("userController");
userController.show();