MongoDB -Aggregation Pagination
let {
allPostsPage = 1,
followingPostsPage = 1,
limit = 25,
userId,
fetchOthersPosts,
} = req.query;
const blockedUsers = await BlockUsers.aggregate([
{
$match: {
$or: [
{ userId: mongoose.Types.ObjectId(userId) },
{ blockedUserId: mongoose.Types.ObjectId(userId) },
],
},
},
]);
allPostsPage = parseInt(allPostsPage);
followingPostsPage = parseInt(followingPostsPage);
const blockedUserIds = [];
blockedUsers.map((user) => {
if (user.userId.toString() === userId.toString()) {
blockedUserIds.push(user.blockedUserId);
} else if (user.blockedUserId.toString() === userId.toString()) {
blockedUserIds.push(user.userId);
}
});
let noMoreFollowingPosts = false;
let posts = [];
let fakeTotalPagesFlag = false;
let initialPosts = [];
const followingList = await Followers.aggregate([
{ $match: { following: mongoose.Types.ObjectId(userId) } },
{ $project: { userId: 1, _id: 0, requestAccepted: 1 } },
]);
const followingListIds = []
followingList.map((e) => {
if (e.requestAccepted === true || !e.hasOwnProperty("requestAccepted")) {
followingListIds.push(mongoose.Types.ObjectId(e.userId));
}
});
let noFollowers = false;
if (followingListIds.length < 1) {
fetchOthersPosts = "true";
noFollowers = true;
}
// let queryFilter=;
if (fetchOthersPosts === "false") {
posts = await Post.aggregate([
{
$lookup: {
from: "users",
let: { userId: "$userId" },
pipeline: [
{
$match: {
$expr: { $eq: ["$_id", "$$userId"] },
},
},
{ $project: { fullName: 1, userName: 1, email: 1, image: 1, privateAccount: 1 } },
],
as: "users",
},
},
{
$addFields: {
userId: {
$arrayElemAt: ["$users", 0],
},
dayssince: {
$trunc: {
$divide: [
{ $subtract: [new Date(), "$createdAt"] },
1000 * 60 * 60 * 24,
],
},
},
},
},
{
$match: {
$or: [
{ "userId._id": { $in: followingListIds } },
{
$and: [
{ "userId._id": mongoose.Types.ObjectId(userId) },
{ dayssince: { $lt: 2 } },
],
},
],
},
},
{
$lookup: {
from: "ingredients",
localField: "ingredients.id",
foreignField: "_id",
as: "output"
}
},
{
$addFields: {
"ingredients.name": "$output.name"
}
},
{ $project: { output: 0, postLikes: 0, userLiked: 0, ingredient: 0, dayssince: 0, users: 0, comments: 0, image: 0, video: 0 } },
{ $sort: { createdAt: -1 } },
{
$facet: {
stage1: [{ $group: { _id: null, count: { $sum: 1 } } }],
stage2: [
{
$skip: (followingPostsPage - 1) * limit,
},
{ $limit: limit * 1 },
],
},
},
{
$unwind: {
path: "$stage1",
},
},
{
$project: {
count: "$stage1.count",
data: "$stage2",
},
},
]);
let filteredPostsCount = posts[0] ? posts[0].data.length : 0;
let count = posts[0] ? posts[0].count : 0;
