将文档插入数据库之前，MongoDB空集合

Question

I'm trying to implement a function to empty the collection every time I populate document into the database. This doesn't work for me. I also tried using async.series , but still no luck. Why doesn't this code below work? The output always with db.users.find().count() gave me 0 .

function emptyThenInsert(db) {
  UserSchema.collection.remove({}, function(err) {
    if(err) console.log(err);
    UserSchema.collection.insert(db, function(err, data) {
      console.log(data);
      if (err) console.log(err);
      UserSchema.collection.find({}, function(err, data) {
        console.log(data);
        if (err) console.log(err);
      });
    });
  });
}

It works if I take out UserSchema.collection.remove .

Answer 1

This seem to work for me.

function emptyThenInsert(db) {
  UserSchema.remove({}, function(err) {
    if(err) console.log(err);
    UserSchema.collection.insert(db, function(err, data) {
      if (err) console.log(err);
      UserSchema.collection.find({}, function(err, data) {
        if (err) console.log(err);
      });
      process.exit(1);
    });
  });
}

Answer 2

尝试使用写关注点：

UserSchema.collection.insert(db, {w:1}, function(err, data) {