I want to use groupBy clause on a pouchdb query. As per the documentation https://www.npmjs.com/package/pouchdb-gql the code goes like this:
import PouchDB from 'pouchdb-react-native';
var GQL = require('GQL');
PouchDB.plugin({ gql: GQL });
db.gql({select: "count(*)", groupBy: "columnX"},
function(err, results) {
console.log(results);
});
I get "Unable to resolve module GQL". Tried replacing the GQL with "pouchdb-gql", I get db.gql is not a function. Please help.
Is there a way to achieve "groupBy" using pouchdb-find?
Related
I am trying to add a number to an item in a document in MongoDB
I have this code:
const schema = require('./commands/serverstats')
const data = await schema.findOne({ Main:'Main' })
data.TotalBobuxGiven += Number(args[0])
data.TotalRobuxGiven += Number(args[1])
await data.save()
message.reply(`Done`)
console.log('done')
It doesn't return done or it doesn't add the data properly. The schema is correct, and I am using the correct variables. There are no errors. What am I doing wrong?
Query
try update, and 1 query, making the update faster atomic and safe
*i dont use mongoose, but you dont need find and save, update is the right way to do it
Test code here
db.collection.update({
Main: "Main"
},
{
$inc: {
"TotalBobuxGiven": Number(args[0]),
"TotalRobuxGiven": Number(args[1])
}
})
I am trying to use Mongoose pre and post hooks in my MongoDB backend in order to compare the document in its pre and post-saved states, in order to trigger some other events depending on what's changed. So far however I'm having trouble getting the document via the Mongoose pre hook.
According to the docs "pre hooks work for both doc.save() and doc.update(). In both cases this refers to the document itself... ". So I here's what I tried. First in my model/schema I have the following code:
let Schema = mongoose
.Schema(CustomerSchema, {
timestamps: true
})
.pre("findOneAndUpdate", function(next) {
trigger.preSave(next);
})
// other hooks
}
... And then in my triggers file I have the following code:
exports.preSave = function(next) {
console.log("this: ", this);
}
};
But this is what logs to the console:
this: { preSave: [Function], postSave: [AsyncFunction] }
So clearly this didn't work. This didn't log out the document as I was hoping for. Why is this not the document itself here, as the docs themselves appear to indicate? And is there a way I can get a hold of the document with a pre hook? If not, is there another approach people have used to accomplish this?
You can't retrieve the document in the pre hook.
According to the documentation pre is a query middleware and this refers to the query and not the document being updated.
The confusion arises due to the difference in the this context within each of the kinds of middleware functions. During document pre or post middleware, you can use this to access the document model, but not in the other hooks.
There are three kinds of middleware functions, all of which have pre and post stages.
In document middleware functions, this refers to the document (model).
init, validate, save, remove
In query middleware functions, this refers to the query.
count,find,findOne,findOneAndRemove,findOneAndUpdate,update
In aggregate middleware, this refers to the aggregation object.
aggregate
It's explained here https://mongoosejs.com/docs/middleware.html#types-of-middleware
Therefore you can simply access the document during pre("init"), pre("init"), pre("validate"), post("validate"), pre("save"), post("save"), pre("remove"), post("remove"), but not in any of the others.
I've seen examples of people doing more queries within the other middleware hooks, to find the model again, but that sounds pretty dangerous to me.
The short answer seems to be, you need to change the original query to be document oriented, not query or aggregate style. It does seem like an odd limitation.
As per documentation you pre hook cannot get the document in function, but it can get the query as follow
schema.pre('findOneAndUpdate', async function() {
const docToUpdate = await this.model.findOne(this.getQuery());
console.log(docToUpdate); // The document that findOneAndUpdate() will modify
});
If you really want to access document (or id) in query middleware functions
UserSchema.pre<User>(/^(updateOne|save|findOneAndUpdate)/, async function (next) {
const user: any = this
if (!user.password) {
const userID = user._conditions?._id
const foundUser = await user.model.findById(userID)
...
}
If someone needs the function to hash password when user password changes
UserSchema.pre<User>(/^(updateOne|save|findOneAndUpdate)/, async function (next) {
const user: any = this
if (user.password) {
if (user.isModified('password')) {
user.password = await getHashedPassword(user.password)
}
return next()
}
const { password } = user.getUpdate()?.$set
if (password) {
user._update.password = await getHashedPassword(password)
}
next()
})
user.password exists when "save" is the trigger
user.getUpdate() will return props that changes in "update" triggers
In Mongoose, I can use a query populate to populate additional fields after a query. I can also populate multiple paths, such as
Person.find({})
.populate('books movie', 'title pages director')
.exec()
However, this would generate a lookup on book gathering the fields for title, pages and director - and also a lookup on movie gathering the fields for title, pages and director as well. What I want is to get title and pages from books only, and director from movie. I could do something like this:
Person.find({})
.populate('books', 'title pages')
.populate('movie', 'director')
.exec()
which gives me the expected result and queries.
But is there any way to have the behavior of the second snippet using a similar "single line" syntax like the first snippet? The reason for that, is that I want to programmatically determine the arguments for the populate function and feed it in. I cannot do that for multiple populate calls.
After looking into the sourcecode of mongoose, I solved this with:
var populateQuery = [{path:'books', select:'title pages'}, {path:'movie', select:'director'}];
Person.find({})
.populate(populateQuery)
.execPopulate()
you can also do something like below:
{path:'user',select:['key1','key2']}
You achieve that by simply passing object or array of objects to populate() method.
const query = [
{
path:'books',
select:'title pages'
},
{
path:'movie',
select:'director'
}
];
const result = await Person.find().populate(query).lean();
Consider that lean() method is optional, it just returns raw json rather than mongoose object and makes code execution a little bit faster! Don't forget to make your function (callback) async!
This is how it's done based on the Mongoose JS documentation http://mongoosejs.com/docs/populate.html
Let's say you have a BookCollection schema which contains users and books
In order to perform a query and get all the BookCollections with its related users and books you would do this
models.BookCollection
.find({})
.populate('user')
.populate('books')
.lean()
.exec(function (err, bookcollection) {
if (err) return console.error(err);
try {
mongoose.connection.close();
res.render('viewbookcollection', { content: bookcollection});
} catch (e) {
console.log("errror getting bookcollection"+e);
}
//Your Schema must include path
let createdData =Person.create(dataYouWant)
await createdData.populate([{path:'books', select:'title pages'},{path:'movie', select:'director'}])
I am working on a express js project.I have got all my basic routing set up working perfectly. Usually when I want to search a record based on id I do this:
router.route('/sensors_home/:sensor_id')
.get(function (req, res) {
Sensor.findById(req.params.sensor_id,function(err, sensorInfo) {
if (err)
res.send(err);
res.send(sensorInfo);
});
});
This allows me to retrieve the data when I do http://localhost:4000/sesnors_home/45000cbsfdhjbnabfbajhdb
(45000cbsfdhjbnabfbajhdb = Object id from the MongoDB )
Now my goal is to have several users to my application. I have my mongoose schema set up and the mongoDB looks like this :
Here is the issue: I wanna retrieve data corresponding to John Peterson based on his _id that is "John".Instead of doing this http://localhost:4000/sesnors_home/45000cbsfdhjbnabfbajhdb I wanna do something like this http://localhost:4000/sesnors_home/John and retrieve all the data specific to John. I tried various methods but still stuck with this issue. I tried using req.params._id and also some Mongodb queries on the User Collection but still no luck. Please suggest some ideas.
Thanks!
UPDATE:
I tried using the following code :
router.route('/sensors_home/:id')
.get(function (req, res) {
res.send(_id.toString());
User.findOne({_id: req.params._id} ,function(err, sensorInfo) {
if (err)
res.send(err);
res.send(sensorInfo);
});
});
This gives me the following error :
ReferenceError: _id is not defined
Have you tried the following?
router.route('/sensors_home/:_id')
.get(function (req, res) {
Sensor.findOne({_id: req.params._id},function(err, sensorInfo) {
if (err)
res.send(err);
res.send(sensorInfo);
});
});
I want to add to the return data from a mongoose query:
User.findById(userId, function(err, data) {
if (!err) {
data.newvar = 'Hello, world';
}
});
However, when I console log the output, the newvar does not exist. I've also tried this using Underscore's extend:
_.extend(data, {'newvar': 'Hello, world'});
With no luck either. Since I have nested documents, using a shallow copy won't work. Is there any way to append data here?
One way to handle this is to convert your mongoose model instance into a plain object that you have full control over by calling toObject() on it:
User.findById(userId, function(err, data) {
if (!err) {
data = data.toObject();
data.newvar = 'Hello, world';
}
});
If you want a more structured solution, you can add virtual attributes to your schema as described here.
As it turns out, Mongoose documents are their own special class and not standard Javascript objects. In order to get a javascript option that can be extended, you must use the toObject() method.
Now you can use lean() method to return a plain js object:
User.findById(userId)
.lean()
.exec( function(err, data) {
if (!err) {
data.newvar = 'Hello, world';
}
});
Why can't you modify the data returned by a Mongoose Query (ex: findById)