I want to populate fields after mapReduce.
mongoose.connection.db.collection('createdCollectionNameForResults', function(err, collection) {
collection.find({}).populate('ref_field').toArray(function(err, items) {
res.send(200, items)
});
});
But here, it gives error:
TypeError: Object # has no method 'populate'
Because collection.find({}) returns mongodb cursor. How can I populate ref_field?
Considering that you have a Schema registered in mongoose named 'createdCollectionNameForResults'
var Model = mongoose.model('createdCollectionNameForResults');
Model.find({}).populate('ref_field').exec(function(err, results){
console.log(err, results);
});
Related
I'm trying to return create a paginated list. I used graphql to query the data. With my query, I pass the number of records I need (In a variable named first) and the ID of the last fetched record (In a varible called after). Now I managed to write a query (Note that I used mongoose) to fetch the records. Now what I need to do is get the relavant information to perform the pagination like hasNextPage, hasPreviousPage, currentPage and totalPages.
To get most of these information I need to get the total number of records in the database. To do that I need to send another db request.
I also need to know the position of the record in the table. No idea how.
Here's the query:
new Promise((resolve, reject) =>
Company.where('_id')
.gt(after)
.limit(first)
.lean()
.exec((error, doc) => {
if (error) {
reject(error);
}
resolve({
edges: doc,
pageInfo: {
hasNextPage: '...',
hasPreviousPage: '...',
currentPage: '...',
totalPages: '...'
}
});
}))
Any idea how to do this efficiently?
you can try this module mongoose-paginate
here what i uses, for pagination,
var current = req.query.filter.current;
var limit = req.query.filter.limit;
console.log('params.query.filter.current',current);
var skip = Number(limit)*Number(current)-Number(limit);
console.log('skip::',skip);
Cours.find({'attributes.version.status': true}).skip(skip).limit(limit).sort({_id:'asc'}).exec(function (err, resulta) {
if (err) {
console.log('erreur trouverCours');
res.json({
protecteds: err
});
}
console.log('cours ::', resulta);
res.json({
"data": resulta
});
});
I am writing a service class (mongo_service.js) in order to keep my CRUD operations seperate for a project.
Below is the code to update multiple items.
updateMultipleCollection(Model, searchObject, collectionNewToUpdate) {
return new Promise(function (resolve, reject) {
Model.update( searchObject, collectionNewToUpdate, {new:true, multi:true}, function (err, data) {
if (err) {
reject(err);
}
resolve (data);
console.info("Multiple updates successful");
});
});
};
This works fine but the promise won't return the updated objects and I was wondering whether there was any other way to overcome this??
NOTE: In mongoose documentation they have mentioned that .update() will not return the updated objects whereas .findOneAndUpdate() does.
you could do a .find() and that will return an array.
Then do a forEach over the array and do .save on each doc. The new doc should be in the callback of .save
I am sending a query to mongoDB using mongoose. The collection is named Step. I want the result of this query to be an array of _id values, one per step. Currently I am getting all of the step objects in their entirety, because req.query isn't defined in this case.
service:
this.getSteps = function() {
return $http({
method: 'GET',
url: '/api/step'
})
.then(function(response) {
return response.data;
});
};
controller:
readStep: function (req, res) {
Step.find(req.query, function(err, result) {
if (err) {
res.status(500).send(err);
}
res.status(200).send(result);
});
}
Set the second parameter of the find query to '_id' to retrieve only the _id of the objects.
Step.find(req.query, '_id', function(err, result) {
This will return data like this:
[{_id: 123}, {_id: 234}]
If you want to get an array of the Step ids on their own, use the javascript map function like so
result = result.map(function(doc) {
return doc._id;
});
which will give you an array like this:
[123, 234]
You'll need to use query.select, something like as shown below:
Step.find(query).select({ "_id": 1}).then(....);
I'm not able to type much because I'm responding from my handheld.
Hope this help!
All the examples I have seen for MongoDb & Mongoskin for update, have individual properties being updated, like so:
// this works when I specify the properties
db.collection('User').update({_id: mongoskin.helper.toObjectID(user._id)},
{'$set':{displayName:user.displayName}}, function(err, result) {
if (err) throw err;
if (result){ res.send(result)}
});
But what if I wanted the whole object/document to be updated instead:
// this does not appear to work
db.collection('User').update({_id: mongoskin.helper.toObjectID(user._id)}, {'$set':user},
function(err, result){
// do something
}
It returns the error:
// It appears Mongo does not like the _id as part of the update
MongoError: After applying the update to the document {_id: ObjectId('.....
To overcome this issue, this is what I had to do to make things work:
function (req, res) {
var userId = req.body.user._id
var user = req.body.user;
delete user._id;
db.collection('User').update({_id: mongoskin.helper.toObjectID(userId)},
{'$set':user}, function(err, result) {
if (err) throw err;
console.log('result: ' + result)
if (result){ res.send(result)}
});
})
It there a more elegant way of updating the whole document, instead of hacking it with:
delete user._id
If you want to update the whole object, you do not need a $set. I am not aware of mongoskin, but in shell you would do something like:
var userObj = {
_id: <something>
...
};
db.user.update({_id: user._id}, user);
Which I think can be translated in your mongoskin in the following way.
db.collection('User').update({_id: user._id}, user, function(){...})
But here is the problem. You can not update _id of the element in Mongo. And this is what your error tells you. So you can remove the _id from your user object and have it separately. Search by this separate _id and update with a user object without _id.
I'm using a MEAN stack and with Mongoose. Is there a way to query MongoDB with multiple ids to only return those specific IDs in one query e.g. /api/products/5001,5002,5003
Is this possible or would I need to query each product individually or add an additional attribute to the products and query by that.
Update: To clarify as suggested below I've managed to get it partially working using {'_id': { $in: [5001,5002,5003]} however I'm having problems figuring out how to pass the list from the api url to the find function.
Using Express.js for router
router.get('/list/:ids', controller.showByIDs);
exports.showByIDs = function(req, res) {
Product.find({'_id': { $in: [req.params.ids]}}, function (err, product) {
if(err) { return handleError(res, err); }
if(!product) { return res.send(404); }
return res.json(product);
})
};
Then trying /api/products/list/5001 works however /api/products/list/5001,5002 doesn't. I'm not sure if it's a syntax problem in the url or my router code that needs to change or the controller.
You can use the $in operator to query for multiple values at once:
Products.find({_id: {$in: [5001, 5002, 5003]}}, function (err, products) { ... });
On the Express side, you need to use a format for the ids parameter that lets you split it into an array of id values, like you had in your first example:
/api/products/5001,5002,5003
Then in your route handler, you can call the split function on the req.params.ids string to turn it into an array of id values that you can use with $in:
exports.showByIDs = function(req, res) {
var ids = req.params.ids.split(',');
Product.find({'_id': { $in: ids}}, function (err, product) {
if(err) { return handleError(res, err); }
if(!product) { return res.send(404); }
return res.json(product);
})
};