Implement a mandatory route in Express

Question

Implement a mandatory route in Express

Is it possible to enforce a specific route?

Scenario:

Consider the following route A:

notiSchema = notification model

router.get('/set', function(req, res){
    User.findById("userId", function(err, foundUser){
        foundUser.notiSchemaSent.forEach(function(notiSchema, i){
            if(req.user.notifications.length === 0){
                req.user.notifications.unshift(notiSchema);
                req.user.save();
            } else {
                req.user.notifications.forEach(function(userSchema, i){
                    if(req.user.notifications.indexOf(notiSchema) === -1){
                         req.user.notifications.unshift(notiSchema);
                         req.user.save();
                    }
                });
            }
        });
    });

    res.json(req.user.notifications);
});

The issue here is that the 'res.json' line is executed before userB is updated

Therefore, I have created another route B:

router.get('/get', middleware.isLoggedIn, function(req, res){
  res.json(req.user.notifications);
});

Here is my Ajax request:

$.get('/set', function(data){
    // Adding "fa-spin" class here only
}).then(function(){
    $.get('/get', function(data){
        $(data).each(function(i, item){
            $('.notDrop').prepend(item);
        });

        // Remove the "fa-spin" class
    });
});

However, there are instances where route "B" is called before route "A" is fully completed;

Thus, I am curious to know if it's feasible to trigger route "B" only after route "A" has completely finished processing.

javascript ajax mongodb express asynchronous

Answer 1

Answer №1

I have revised the route to consolidate all changes into req.user.notifications, saving only once at the end if the array was modified. This approach allows for a single .save() operation with a callback function to indicate when it's completed.

Key modifications:

Accumulate changes in the array and save at the end.
Save only if the array was altered.
Removed special case for .length === 0 as it's unnecessary.
Implemented a callback on req.user.save() for tracking completion and sending response post-save.
Incorporated error handling for both .save() and .findById().

Here is the updated code snippet:

router.get('/set', function(req, res){
    User.findById("userId", function(err, foundUser){
        // Error handling for finding user
        if (err) {
           console.log(err);
           res.status(500).send("Error finding user.")
           return;
        }
        let origLength = req.user.notifications.length;
        foundUser.notiSchemaSent.forEach(function(notiSchema, i){
            req.user.notifications.forEach(function(userSchema, i){
                if(req.user.notifications.indexOf(notiSchema) === -1){
                    req.user.notifications.unshift(notiSchema);
                }
            });
        });
        // Save only if there are modifications in notifications array
        if (req.user.notifications.length !== origLength) {
            req.user.save(function(err) {
                // Error handling for saving user notifications
                if (err) {
                    console.log(err);
                    res.status(500).send("Error saving user notifications.")
                } else {
                    res.json(req.user.notifications);
                }
            });
        } else {
            res.json(req.user.notifications);
        }
    });
});

If you adjust your database code to retrieve an array of users from the find operation, you can process them as follows:

router.get('/set', function(req, res){
    User.find({_id: {$in: arrayOfIds}}, function(err, foundUsers){
        // Error handling for finding multiple users
        if (err) {
           console.log(err);
           res.status(500).send("Error finding user.")
           return;
        }
        let origLength = req.user.notifications.length;
        foundUsers.forEach(function(foundUser) {
            foundUser.notiSchemaSent.forEach(function(notiSchema, i){
                req.user.notifications.forEach(function(userSchema, i){
                    if(req.user.notifications.indexOf(notiSchema) === -1){
                        req.user.notifications.unshift(notiSchema);
                    }
                });
            });
        });
        // Save only if there are modifications in notifications array
        if (req.user.notifications.length !== origLength) {
            req.user.save(function(err) {
                // Error handling for saving user notifications
                if (err) {
                    console.log(err);
                    res.status(500).send("Error saving user notifications.")
                } else {
                    res.json(req.user.notifications);
                }
            });
        } else {
            res.json(req.user.notifications);
        }
    });
});

Answer 2

I have revised the route to consolidate all changes into req.user.notifications, saving only once at the end if the array was modified. This approach allows for a single .save() operation with a callback function to indicate when it's completed.

Key modifications:

Accumulate changes in the array and save at the end.
Save only if the array was altered.
Removed special case for .length === 0 as it's unnecessary.
Implemented a callback on req.user.save() for tracking completion and sending response post-save.
Incorporated error handling for both .save() and .findById().

Here is the updated code snippet:

router.get('/set', function(req, res){
    User.findById("userId", function(err, foundUser){
        // Error handling for finding user
        if (err) {
           console.log(err);
           res.status(500).send("Error finding user.")
           return;
        }
        let origLength = req.user.notifications.length;
        foundUser.notiSchemaSent.forEach(function(notiSchema, i){
            req.user.notifications.forEach(function(userSchema, i){
                if(req.user.notifications.indexOf(notiSchema) === -1){
                    req.user.notifications.unshift(notiSchema);
                }
            });
        });
        // Save only if there are modifications in notifications array
        if (req.user.notifications.length !== origLength) {
            req.user.save(function(err) {
                // Error handling for saving user notifications
                if (err) {
                    console.log(err);
                    res.status(500).send("Error saving user notifications.")
                } else {
                    res.json(req.user.notifications);
                }
            });
        } else {
            res.json(req.user.notifications);
        }
    });
});

If you adjust your database code to retrieve an array of users from the find operation, you can process them as follows:

router.get('/set', function(req, res){
    User.find({_id: {$in: arrayOfIds}}, function(err, foundUsers){
        // Error handling for finding multiple users
        if (err) {
           console.log(err);
           res.status(500).send("Error finding user.")
           return;
        }
        let origLength = req.user.notifications.length;
        foundUsers.forEach(function(foundUser) {
            foundUser.notiSchemaSent.forEach(function(notiSchema, i){
                req.user.notifications.forEach(function(userSchema, i){
                    if(req.user.notifications.indexOf(notiSchema) === -1){
                        req.user.notifications.unshift(notiSchema);
                    }
                });
            });
        });
        // Save only if there are modifications in notifications array
        if (req.user.notifications.length !== origLength) {
            req.user.save(function(err) {
                // Error handling for saving user notifications
                if (err) {
                    console.log(err);
                    res.status(500).send("Error saving user notifications.")
                } else {
                    res.json(req.user.notifications);
                }
            });
        } else {
            res.json(req.user.notifications);
        }
    });
});

Implement a mandatory route in Express

Answer №1

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