I have two Sequelize queries that I need to run in a specific order, the first creates a model and the second creates multiple models from an array. It works in that it inserts obj1 first and then the array of transactions, however the final 'then()' doesn't seem to get called... What am I doing wrong?
var fn = function addTransaction(transaction) {
return new Promise(function() {
return Transaction.create(transaction, { fields: [ 'Id', 'Name' ]});
}
};
var transactions = [...]; //array of transaction objects
Model1.create(obj1, { fields: [ 'Id', 'Name' ,'Description' ]}).then(function() {
var actions = transactions.map(fn);
var results = Promise.all(actions).then(function(data) {
return Promise.all(data.map(fn));
});
results.then(function() {
console.log("Done?"); //not getting called
});
}).catch(function(err) {
console.log(err);
});
addTransaction() is never going to resolve the promise it creates. You create an outer promise and return it, but never resolve it. You would at least have to declare a resolve argument to that callback and then call resolve() somewhere.
But, if Transaction.create() already returns a promise, then you can change addTransaction() to this:
var fn = function addTransaction(transaction) {
return Transaction.create(transaction, { fields: [ 'Id', 'Name' ]});
};
It's also unclear why you're using the same fn to process both the transactions array and the data array that results from each of those transactions. That seems a little odd from a logic point of view. Are you sure that's the correct way to write your code? For us to help you with the design of that part of the code, you'd have to explain more about what you're trying to accomplish by calling fn on both the first array of transactions and then again on the results from that.
I'm not sure if this will solve your problem exactly, but I think you are missing a return:
...
return results.then(function() {
console.log("Done?"); //not getting called
});
...
Without it the Model1.create promise would resolve before the results finish.
Related
Recently, I changed key of object in MongoDB.
{
links: {
changed: 'value',
notchanged: 'value'
}
}
This is what I get from my MongoDB collection. Data which key is not changed is still readable by links.notchanged but data which key is changed like links.changed is not readable and only outputs undefined. Node.js gets and reads the whole links data correctly but when it comes to links.changed it doesn't. How do I solve this problem? Code below:
scheme.findOne({}, (err, data) => {
if (err) res.send('ERR')
else {
console.log(data) // prints full data, same as JSON above
console.log(data.links.changed) // undefined
}
}
You are matching {class:'210'}.. Is it available in document. Probably Your query returns empty object in data . Confirm the match query... Otherwise your code seems ok.
await db1.findOne({class: "210"}, (err, data) => {
console.log(data.links.changed) // returns value
})
Or Try the code like this
await db1.find({ class: "210" }).toArray()
.then(data => {
console.log(data[0].links.changed) //"value"
});
You should make a variable instead of an object for this. For example: Use changed and assign it value as true or false
Good morning.
I'm quite new to NodeJS / sequelize world and I'm currently facing a problem while trying to display a dashboard on screen.
This dashboard has three filters: two dates (period), client name, and employee name. The user can select none, one, two, or all the filters and my database needs to work accordingly.
That being said, my problem is with Sequelize because I don't know how to treat this problem of parameters not being "always" there.
I've seen this question:
Sequelize optional where clause parameters?
but this answer doesn't work anymore. I also tried another way of building the where clause, but I failed on it as well (mainly due to sequelize operators).
The last thing I tried was to make a single query with all parameters included but try to find some value (or flag) that would make sequelize ignore the parameter, for the case when the parameter was no there*, but it looks like Sequelize doesn't have anything like that.
* I've read a question here that has an answer saying that {} would do the trick but I tried that as well but didn't work.
In summary: I need to make a query that can "change" over time, for example:
Foo.findAll({
where: {
id : 1,
}
});
Foo.findAll({
where: {
id {
[Op.in] : [1,2,3,4,5]
},
name: "palmeiira",
}
});
Do you know a way of doing it without the need of using a lot if / switch statements?
I'm currently using Sequelize v. 5.5.1.
Update
I tried doing as suggested by #Anatoly and created a function to build the parameters. It was something like that. (I tried a "smaller" version just to test)
async function test() {
const where = {};
where[Op.and] = [];
where[Op.eq].push({
id: {
[Op.in]: [1,2,3]
}
});
return where;
}
I setted the return value to a const:
const query = await test()
And tried console.log(query)
The result was: { [Symbol(and)]: [ { id: [Object] } ] }, which made me believe that the problem was parsing the Op part so i tried using 'Op.and' and 'Op.in' to avoid that and it solved this problem, but led to another on sequelize that said Invalid value
Do you have any idea where is my error ?
P.S.: #Anatoly very nice idea you gave me on original answer. Thank you very much.
If these three conditions should work together then you can use Op.and with an array of conditions:
const where = {}
if (datesFilter || clientNameFilter || employeenameFilter) {
where[Op.and] = []
if (datesFilter) {
where[Op.and].push({
dateField: {
[Op.between]: [datesFilter.start, datesFilter.finish]
}
})
}
if (clientNameFilter) {
where[Op.and].push({
name: {
[Op.iLike]: `%${clientNameFilter.value}%`
}
})
}
if (employeenameFilter) {
where[Op.and].push({
employeeName: {
[Op.iLike]: `%${employeenameFilter.value}%`
}
})
}
}
const dashboardItems = await DashboardItem.findAll({ where }, {
// some options here
})
If the conditions should work as alternatives then just replace Op.and with Op.or
I'm developing a small NodeJS web app using Mongoose to access my MongoDB database. A simplified schema of my collection is given below:
var MySchema = mongoose.Schema({
content: { type: String },
location: {
lat: { type: Number },
lng: { type: Number },
},
modifierValue: { type: Number }
});
Unfortunately, I'm not able to sort the retrieved data from the server the way it is more convenient for me. I wish to sort my results according to their distance from a given position (location) but taking into account a modifier function with a modifierValue that is also considered as an input.
What I intend to do is written below. However, this sort of sort functionality seems to not exist.
MySchema.find({})
.sort( modifierFunction(location,this.location,this.modifierValue) )
.limit(20) // I only want the 20 "closest" documents
.exec(callback)
The mondifierFunction returns a Double.
So far, I've studied the possibility of using mongoose's $near function, but this doesn't seem to sort, not allow for a modifier function.
Since I'm fairly new to node.js and mongoose, I may be taking a completely wrong approach to my problem, so I'm open to complete redesigns of my programming logic.
Thank you in advance,
You might have found an answer to this already given the question date, but I'll answer anyway.
For more advanced sorting algorithms you can do the sorting in the exec callback. For example
MySchema.find({})
.limit(20)
.exec(function(err, instances) {
let sorted = mySort(instances); // Sorting here
// Boilerplate output that has nothing to do with the sorting.
let response = { };
if (err) {
response = handleError(err);
} else {
response.status = HttpStatus.OK;
response.message = sorted;
}
res.status(response.status).json(response.message);
})
mySort() has the found array from the query execution as input and the sorted array as output. It could for instance be something like this
function mySort (array) {
array.sort(function (a, b) {
let distanceA = Math.sqrt(a.location.lat**2 + a.location.lng**2);
let distanceB = Math.sqrt(b.location.lat**2 + b.location.lng**2);
if (distanceA < distanceB) {
return -1;
} else if (distanceA > distanceB) {
return 1;
} else {
return 0;
}
})
return array;
}
This sorting algorithm is just an illustration of how sorting could be done. You would of course have to write the proper algorithm yourself. Remember that the result of the query is an array that you can manipulate as you want. array.sort() is your friend. You can information about it here.
When I make a Sequelize query it returns to me an object (or array) which I'm guessing is a Sequelize model (or array of Models (a collection type??)) but it's not documented anywhere, so I'm just guessing. I would always like the results to be JSON. Is there anything I can pass in the query to force this? I would prefer not to hand massage every result I get back to be JSON if possible.
The documentation show this to return a string:
console.log(JSON.stringify(users))
So there's some built in serialization. Right now I'm doing this, using the undocumented toJSON() method:
query().then(function(result) {
if(result.length) {
return result.toJSON();
} else {
return result.map(function(item) {
return item.toJSON();
});
}
});
which is cumbersome.
You can use raw: true in the Query however this does not always behave as you might expect, especially with associations.
query({
// ...
raw: true
}).then(function(result) {
// Result is JSON!
});
However in the case where you're using associations you may get something like this:
{
foo: true,
"associated.bar": true
}
Instead of what you might expect:
{
foo: true,
associated: {
bar: true
}
}
When you retrieve the model from the database, you can call the .get({ plain: true}) on the result and it will handle the conversion for you. You can assign the value of the function call to a variable. For example
..).then(function(user){
var _user = user.get({ plain: true});
console.log(_user); //Should be valid json object
});
Hope this helps.
If you're doing a query with which has multiple results you should expect an array to be returned. You should find that each element in the result array is a JSON object.
You should be able to access a given field like this: result[0].myfieldname
This is likely a simple answer but I'm relatively new to asynchronous programming and I'm looking for somebody to point me in the right direction.
My question is this - What is the best way to go about finding or creating a number of documents from an array of names (I'm using Mongoose) and then returning an array of _id's?
So to be clear, I want to:
Given an array of names, find or create a document with each name
Return an array of the existing or newly created documents _ids
You can use async module and within it it's async.parallel() method -
https://github.com/caolan/async#quick-examples
async.parallel([
function(){ ... },
function(){ ... }
], callback);
Or you can use promises and then Q.all() to get the array of ids back -
https://github.com/kriskowal/q#combination
Q.all(arrayOfFindOps).then(function(rows) {
return _.pluck(rows, '_id')
}
If you don't want to use any of the above and do it with callbacks, then you have to keep track of the count of array length, keep adding the ids to an array and when your completion counter reaches array length, call another function with the array you made.
This code can be easily modified to meet your requirements. Call this function for each document that required to be created if doesn't exist.
function(req, reply) {
// return document. if not found, create docuemnt.
docModel.findOne( {'name': req.params.name}, function ( err , doc) {
if(err){
//handle error
}
if(doc===null){
//find failed, time to create.
doc = new docModel( {'name': req.params.name} );
doc.save(function(err){
if(err){
//handle error
}
});
}
return reply(user._id);
});
}