I'm trying to single fetch a value from my database.
I have a collection named: randoms
Model's Name: Random
Inside the collection, I have one object and with a name field. I want to retrieve that value of 'name' and display it in my console.
The result in the console should be: 'TestName' only.
This has been my approach:
Random.find({}, (err, randoms) => {
if(err) throw err
// console.log(randoms)
res.render('entries', console.log(randoms.name))
})
The console displays the result: undefined.
Here's the database.
If I console.log(randoms) instead of console.log(randoms.name) I get the result:
[{
_id: 5e256c819f972c268493488c,
name: 'TestName',
defination: 'Home page paragraph text',
count: 2,
__v: 0
}]
so that means the connection is alright.
db.collection.find returns a Cursor which is A pointer to the result set of a query. Clients can iterate through a cursor to retrieve results.
yourCollection.find().forEach(function(item){})
Related
Apologies if this is basic but I'm struggling to get my head around how to set this up.
I'm using MongoDB/Mongoose for my backend which returns a user object with nested arrays:
{
username: {
type: String,
unique: true
},
name: String,
avatar: String,
recommendations: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Media' }],
watchlist: [{
media: { type: mongoose.Schema.Types.ObjectId, ref: 'Media' },
date_added: Date,
}],
}
If a user visits their watchlist or recommendations page, the nested array gets populated, using mongoose populate(), with the referenced recommendations/watchlist items that they've added.
On the frontend I'm using React Query to handle the data returned from the server. Currently visiting either of the pages returns the whole user object, if I were to cache the entire object using the query key ['user'] the nested array not being populated will be stored as an array of reference id's. Instead I was thinking of maybe trying to update the nested arrays using setQueryData, however this doesn't work if the page is refreshed:
function useWatchlist() {
const { user } = useAuth()
const queryClient = useQueryClient()
const result = useQuery({
queryKey: ['user'],
queryFn: () =>
axios.get(`${baseUrl}/${user.profile_id}/watchlist`).then(response => response.data)
},
{onSuccess: (watchlist) => {
queryClient.setQueryData(['user'], oldUser => {
oldUser.watchlist === watchlist
})
}
})
return {...result, profile: result.data }
}
Should the recommendation/watchlist arrays instead be stored separately using different query keys - ['watchlist']/['recommendations'] or should I attempt to keep the user object structure being returned from the backend?
I would say that yes, you should store them separately. Yet, using relative keys (e.g. ['user', 'watchlist'] and ['user', 'recommendations']) as explained here under Structure:
Structure your Query Keys from most generic to most specific, with as many levels of granularity as you see fit in between
So, you can invalidate them both when the user is refetched.
When I store data such as the "watch list", which only changes when the user changes it, I put a staleTime: Infinity and use setQueryData in the onSuccess of the relevant mutation (when a user updates his watch list).
For the "recommendation list", it's different story, as it would be constantly changing by some logic in the backend. So, I would use invalidateQuery whenever the 'user' key is fetched (or expire the cache, if you update the list each certain interval), and populate it again, on the onSuccess for that query.
I'm trying to get specific info from a javascript object from a mongo database. My code is
tags.find({tagName: tagArgs[1]}, function (err, tag) {
if (err) {
} else {
msg.channel.send(tag.tagContent)
}
})
What I want happened is for the content of the tag to be sent, however, instead it sends nothing. If I instead did
msg.channel.send(tag)
I would get an object
{
_id: 6071ce10c7b87d58acfeac7e,
tagName: 'Test',
tagContent: 'hello world',
__v: 0
}
but trying to tap into tagContent returns nothing, what am I doing wrong?
I can find a document on my database. A call to:
subject = await Subject.find({ name: 'Math' });
res.send(subject);
returns the document correctly:
{
"topics": [],
"_id": "5ab71fe102863b28e8fd1a3a",
"name": "Math",
"__v": 0
}
The problem is when I try to access the properties of subject. Any of the following calls returns nothing:
res.send(subject._id);
res.send(subject.name);
I've tried subject.toObject() and subject.toArray() but I receive an error:
(node:2068) UnhandledPromiseRejectionWarning: TypeError: subject.toObject is not a function
Any help will be appreciated. Thanks!
NB:
before res.send(subject), I called console.log(subject) and the output is:
[ { topics: [],
_id: 5ab71fe102863b28e8fd1a3a,
name: 'cocei5',
__v: 0 } ]
That is because find method in MongoDB always returns an array.
subject = await Subject.find({ name: 'Math' });
So in above line the Subject.find({name: 'Math'}) is returning an array. Which you are storing in subject variable. if you are getting only single object from DB then you might access the object properties by using subject[0].propertyName.
like if you want to send just an id you can do it by
res.send(subject[0]._id);
You can always use the es6 destructuring feature to get the first element returned in the array, as long as you are sure the result will always be on the 0th index.
const [subject] = await Subject.find({ name: 'Math' });
res.send(subject._id);
res.send(subject.name);
ref: Destructuring arrays and objects
Details for find api
OR you can either use
const subject = await Subject.findOne({ name: 'Math' });
res.send(subject._id);
res.send(subject.name);
As findOne return object whereas find returns an array of objects.
ref: Details for findOne api
ExtJS 5.1.x, with several stores using rest proxy.
Here is an example:
Ext.define('cardioCatalogQT.store.TestResults', {
extend: 'Ext.data.Store',
alias: 'store.TestResults',
config:{
fields: [
{name: 'attribute', type: 'string'},
{name: 'sid', type: 'string'},
{name: 'value_s', type: 'string'},
{name: 'value_d', type: 'string'}
],
model: 'cardioCatalogQT.model.TestResult',
storeId: 'TestResults',
autoLoad: true,
pageSize: undefined,
proxy: {
url: 'http://127.0.0.1:5000/remote_results_get',
type: 'rest',
reader: {
type: 'json',
rootProperty: 'results'
}
}
}
});
This store gets populated when certain things happen in the API. After the store is populated, I need to do some basic things, like count the number of distinct instances of an attribute, say sid, which I do as follows:
test_store = Ext.getStore('TestResults');
n = test_store.collect('sid').length);
The problem is that I have to refresh the browser to get the correct value of 'n,' otherwise, the count is not right. I am doing a test_store.load() and indeed, the request is being sent to the server after the .load() is issued.
I am directly querying the backend database to see what data are there in the table and to get a count to compare to the value given by test_store.collect('sid').length);. The strange thing is that I am also printing out the store object in the debugger, and the expected records (when compared to the content in the database table) are displayed under data.items array, but the value given by test_store.collect('sid').length is not right.
This is all done sequentially in a success callback. I am wondering if there is some sort of asynchronous behavior giving me the inconsistent results between what is is the store and the count on the content of the store?
I tested this with another store that uses the rest proxy and it has the same behavior. On the other hand, using the localStorage proxy gives the correct count consistent with the store records/model instances.
Here is the relevant code in question, an Ajax request fires off and does its thing correctly, and hit this success callback. There really isn't very much interesting going on... the problem section is after the console.log('TEST STORE HERE'); where I get the store, print the contents of the store, load/sync then print the store (which works just fine) and then finally print the length of uniquely grouped items by the sid attribute (which is what is not working):
success: function(response) {
json = Ext.decode(response.responseText);
if(json !== null && typeof (json) !== 'undefined'){
for (i = 0, max = json.items.length; i < max; i += 1) {
if (print_all) {
records.push({
sid: json.items[i].sid,
attribute: json.items[i].attribute,
string: json.items[i].value_s,
number: json.items[i].value_d
});
}
else {
records.push({
sid: json.items[i].sid
})
}
}
//update store with data
store.add(records);
store.sync();
// only add to store if adding to search grid
if (!print_all) {
source.add({
key: payload.key,
type: payload.type,
description: payload.description,
criteria: payload.criteria,
atom: payload.atom,
n: store.collect('sid').length // get length of array for unique sids
});
source.sync();
}
console.log('TEST STORE HERE');
test_store = Ext.getStore('TestResults');
test_store.load();
test_store.sync();
console.log(test_store);
console.log(test_store.collect('sid').length)
}
// update grid store content
Ext.StoreMgr.get('Payload').load();
Ext.ComponentQuery.query('#searchGrid')[0].getStore().load();
}
For completeness, here is the data.items array output items:Array[2886]
which is equivalent count of unique items grouped by the attribute sid and finally the output of console.log(test_store.collect('sid').length), which gives the value from the PREVIOUS run of this: 3114...
I'm building an app that has clickable 'filters'; I'm creating a list of objects(?) that I want to pass to a mongo 'find', so that I can pull out listings if selected attributes match a certain score.
My data is structured like this (a snippet):
name: 'Entry One',
location: {
type: 'Point',
coordinates: [-5.654182,50.045414]
},
dogs: {
score: '1',
when: 'seasonal',
desc: 'Dogs allowed from October to April'
},
lifeguard: {
score: '1',
when: 'seasonal',
desc: 'A lifeguard hut is manned between April and October',
times: ''
},
cafe: {
score: '1',
name:'Lovely cafe',
open:'seasonal'
}, ...
My search variable is a list of objects (I think?) that I assign to a session variable. If I output this session var ('searchString') via JSON.stringify, it looks like this:
{"cafe":{"score":"1"},"dogs":{"score":"1"}}
I'd like to pass this to my mongo find so that it only lists entries that match these scores on these attributes, but it's returning zero results. Do I need to somehow make this an $and query?
Currently it looks like this:
Beaches.find(searchString);
Unfortunately as soon as I drop searchString into the find, I get zero results even if it's empty {}. (When it's just a find() the entries list fine, so the data itself is ok)
What am I doing wrong? I'm relatively new to mongo/meteor, so I apologise in advance if it's something stupidly obvious!
Don't stringify the query. Flatten the object instead. Example:
Beaches.find({
"cafe.score": 1,
"dogs.score": 1,
});