Array Filtering Results in an Empty Array of Objects

I'm currently attempting to filter out all objects from the projects array that do not appear in the savedProjects array, but I'm ending up with an empty result. Could it be that I am approaching the filtering process incorrectly?

Here's my code snippet:

router.post('/get-related', async (req, res) => {
console.log(req.body);
try {
    const projects = await Projects.find({researchers: req.body.fullname});
    let savedProjects = await Projects.find({projectID: req.body.projectsIDs});
    projects.filter(p => savedProjects.includes(p) === false);
    res.json(projects);
} catch (err) { 
    console.log(err);
    res.json({ message: err }) };
});

Answer №1

To create a new array with filtered elements without modifying the original, you can utilize the array filter function. An example implementation would look something like this:

let filteredProjects = projects.filter(p => savedProjects.includes(p) === false);  res.json(filteredProjects);

If you want to learn more about Array.filter(), check out MDN's documentation on it.

Answer №2

After implementing the $nin specification, the issue was resolved. I first imported the saved projects and then retrieved all projects that did not contain any of the IDs from the savedProjects array.

router.post('/get-related', async (req, res) => {
try {
    const savedProjects = await Projects.find({projectID: req.body.projectsIDs});
    let IDs = savedProjects.map(p => p.projectID);
    const projects = await Projects.find({ category: req.body.researcharea,  projectID: { $nin: IDs }});
    res.json(projects);
} catch (err) { res.json({ message: err }) };

});

Answer №3

let recommendedOptions = choices.filter(c => savedChoices.some((c)=> c=== true);

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