I have a mongoose object which contains an array of ObjectIds, being used for population from another table. I want to be able to dedupe these. eg I have
[ '61e34f3293d9361bbb5883c7' ,'61e34f3293d9361bbb5883c7', '61e34f3293d9361bbb5883c7' ]
When i print and iterate through these they look like strings.
But they also have an _id property, so I think they're somehow "populated" or at least contain references to the child table.
What's the best way to do this? I tried:
const uniqueTokens = _.uniqBy(tokens, '_id') which doesn't seem to work as _id is some kind of Object.
converting to a string will allow me to dedupe:
const tokens = this.tokens || []
let newTokens: string[] = []
for (let t of tokens) {
const text = t.toString()
// clog.info('t', t, t._id, typeof t._id)
if (!newTokens.includes(text)) {
newTokens.push(text)
}
}
but then these aren't real Objects I can assign back to the original parent object.
// this.tokens = newTokens
await this.save()
I could maybe go through and re-find the objects, but that seems to be digging deeper into the hole!
Seems there must be a better way to handle these type of types...
related searches
How to compare mongoDB ObjectIds & remove duplicates in an array of documents using node.js?
I also tried using lean() on the tokens array to try and convert it back to a simple list of references, in case somehow the 'population' could be undone to help.
I'm down to creating a unique signature field for the referenced items and de-duping based on that.
Related
I have a few collections of data that are in JSON format and want to access specific data conditional data, an example I want to access which one has teacher:true and put it in a state.
I have tried it with conditions inside the loop and filter function.
[
0:{name:"Rou",id:"121"}
1:{name:"Sou",id:"122",teacher:"true"}
2:{name:"Tou",id:"123"}
3:{name:"Vou",id:"124",teacher:"true"}
4:{name:"Kou",id:"125",teacher:"false"}
5:{name:"Wou",id:"126"}
]
here I want to get only
1:{name:"Sou",id:"122",teacher:"true"}
3:{name:"Vou",id:"124",teacher:"true"}
which means only where the teacher is true.
This has nothing to do with react. It's a javascript array problem.
let people = [
{name:"Rou",id:"121"},
{name:"Sou",id:"122",teacher:"true"},
{name:"Tou",id:"123"},
{name:"Vou",id:"124",teacher:"true"},
{name:"Kou",id:"125",teacher:"false"},
{name:"Wou",id:"126"}
];
let teachers = people.filter((person) => person.teacher == "true");
Note that you need it's strongly recommended to use a boolean type instead of a string:
// Strongly discouraged
{name:"Sou",id:"122",teacher:"true"};
// Better
{name:"Sou",id:"122",teacher: true};
I've a REST api that returns the list of locales as dictionary:
{
"en-uk": "English UK",
"en-us": "English USA",
...
}
This dictionary is correctly ordered alphabetically by value.
When AngularJS receives it via HTTP, the dictionary gets automatically re-sorted by key, so when I bind to a select element the list of options is ordered by key, and the alphabetical order by key doesn't match the one by value, I get a wrong sorting.
The problem I suppose is due to the fact that such dictionary becomes basically one object with 800+ properties. How do I sort it by value?
First: You have to find all keys.
Second: Iterate all the keys.
Third: Then sort the array with values.
Please use the following:
let obj = {
"en-us": "English USA",
"en-uk": "English UK"
};
// Get an array of the keys:
let keys = Object.keys(obj);
// Then sort by using the keys to lookup the values in the original object:
keys.sort(function(a, b) { return obj[a] > obj[b] });
console.log(keys);
console.log(obj[keys[0]]);
You can modify the way you send the response from the server. Instead of sending the response as an object, send the stringified object.
The problem is indeed you cannot sort the values of the properties of an object. So I convert it to an array before binding it:
So,
languageResource.getCultures().then(function(cultures) {
vm.availableCultures = cultures;
});
becomes
languageResource.getCultures().then(function (culturesDictionary) {
var cultures = [];
angular.forEach(culturesDictionary, function (value, key) {
cultures.push({
lcid: key,
name: value
});
});
vm.availableCultures = cultures;
});
Seen this when the key is numerical. If the key's data type is string than it would keep its sorted state after an API call. If the key's data type is numerical, than, you would need set the key's value as a string and even add single quotes before and after the key's value, before the API sends it back.
I haven't tried the approach to stringfy the dictionary in the API. After the call you would parse the string back to an object with something like JSON.parse(string) might be your best bet.
I am trying compare two arrays. One array is an array of Person objects, each of which has an email property that is a String email address. The other array is an EmailAddress object which has a descriptive word like "work" or "personal" and the actual String email address.
Basically both objects have a String property for email address. I want to compare these arrays of objects to see if one of the objects from each array has the same email address. Right now I am using nested for loops as shown below but that is taking too long.
for person in self.allPeople! {
for e in EmailAddresses! {
if e.value == person.email {
return true
}
}
}
I thought about using set intersection but that looked like it would only work for comparing the same objects and not object's properties. Thanks.
You can still use Set functionality by first creating a set of all the emails. map helps turn one collection into another, in this case changing your collection of allPeople into a collection of those people's emails. This will be faster because now EmailAddresses is iterated once, instead of once per person.
let personEmails = Set(self.allPeople!.map { $0.email })
let matchingEmails = EmailAddresses!.map { $0.value }
return !personEmails.isDisjoint(with: matchingEmails)
Realmswift Data Model
class User {
let id = RealmOptional<Int>()
dynamic var name = ""
let albums = List<Album>()
override static func primaryKey() -> String {
return "id"
}
}
class Album: Object {
dynamic albumName = ""
let imageIDs = List<ImageID>()
}
class ImageID: Object {
let imageId = RealmOptional<Int>()
}
JSON data
{
"10001": {
"id" : 10001,
"name": "John",
"album": {
"albums": [
{
"albumName": "Summer1999",
"imageIds": [11223, 11224, 11227]
},
{
"albumName": "Xmas1999",
"imageIds": [22991, 22997]
},
{
"albumName": "NewYear2000",
"imageIds": [5556, 776, 83224, 87543]
}
]
}
}
}
I have the above json data and I m using SwiftyJSON to parse the data then write into realm. Everything is working great except for checking and updating of data (for example imageIds on json file have changed).
Question: How do i compare the JSON arrays and RealmSwift List to determine it any updates need to be written into the database?
You can take advantage of your primary key here. As Realm Swift documentation states:
Creating and Updating Objects With Primary Keys: If your model class
includes a primary key, you can have Realm intelligently update or add
objects based off of their primary key values using
Realm().add(_:update:).
So (I assume that you get the JSON from some kind of a request (REST etc.) and then parse it with SwiftyJSON to create a 'User' object) you can treat the new 'User' object as regular new 'User' and try to add it to Realm as usual, but 'update' parameter must be 'true'. If there already was a user with the id of the 'User' object you are trying to add, it will just update the existing 'User' i.e. changing its modified values from the new 'User' created by parsing new JSON data. This might look something like this:
//Parse JSON and create a 'User'
let newUserFromJSON = parseAndCreateUserFromJSON(JSONData)
let realm = try! Realm()
do {
try realm.write {
realm.add(newUserFromJSON, update: true)
}
} catch let error as NSError {
print("error writing to realm: \(error.description) & \(error)")
} catch {
print("error writing to realm: UNKNOWN ERROR")
}
I'm afraid there's probably no easy answer to this. There's no mechanism in Realm to compare the contents of a Realm Object to an external object to see if their data matches. You would need to iterate through each object in the Realm object and manually compare it.
This wouldn't be too much code to write (Since you can get a list of all of the Realm file's properties via the objectSchema property of Realm objects, and then use key-value coding to pull them out in a single for loop), but would still be a fair amount of overhead to perform the compare.
That being said, if what you're wanting to look at is just certain properties that might change (i.e. like you said, just the imageIDs property), then you could easily just check the values you need.
What bcamur has suggested is definitely the quickest (And usually preferred for JSON handing) solution here. As long as you've set your primary key properly, you can call Realm.add(_:, update:) with update set to true to update the object.
Please keep in mind this doesn't merge the new data with what was already in Realm; it'll completely overwrite the old object with the new values, which if it sounds like your ID numbers are changing, would be the best course of action.
Say I'd like to fetch only items that contains keys: "-Ju2-oZ8sJIES8_shkTv", "-Ju2-zGVMuX9tMGfySko", and "-Ju202XUwybotkDPloeo".
var items = new Firebase("https://hello-cambodia.firebaseio.com/items");
items.orderByKey().equalTo("-Ju2-gVQbXNgxMlojo-T").once('value', function(snap1){
items.orderByKey().equalTo("-Ju2-zGVMuX9tMGfySko").once('value', function(snap2){
items.orderByKey().equalTo("-Ju202XUwybotkDPloeo").once('value', function(snap3){
console.log(snap1.val());
console.log(snap2.val());
console.log(snap3.val());
})
})
});
I don't feel that this is the right way to fetch the items, especially, when I have 1000 keys over to fetch from.
If possible, I really hope for something where I can give a set of array
like
var itemKeys = ["-Ju2-gVQbXNgxMlojo-T","-Ju2-zGVMuX9tMGfySko", "-Ju202XUwybotkDPloeo"];
var items = new Firebase("https://hello-cambodia.firebaseio.com/items");
items.orderByKey().equalTo(itemKeys).once('value', function(snap){
console.log(snap.val());
});
Any suggestions would be appreciated.
Thanks
Doing this:
items.orderByKey().equalTo("-Ju2-gVQbXNgxMlojo-T")
Gives exactly the same result as:
items.child("-Ju2-gVQbXNgxMlojo-T")
But the latter is not only more readable, it will also prevent the need for scanning indexes.
But what you have to answer is why want to select these three items? Is it because they all have the same status? Because they fell into a specific date range? Because the user selected them in a list? As soon as you can identify the reason for selecting these three items, you can look to convert the selection into a query. E.g.
var recentItems = ref.orderByChild("createdTimestamp")
.startAt(Date.now() - 24*60*60*1000)
.endAt(Date.now());
recentItems.on('child_added'...
This query would give you the items of the past day, if you had a field with the timestamp.
You can use Firebase child. For example,
var currFirebaseRoom = new Firebase(yourFirebaseURL)
var userRef = currFirebaseRoom.child('users');
Now you can access this child with
userRef.on('value', function(userSnapshot) {
//your code
}
You generally should not be access things using the Firebase keys. Create a child called data and put all your values there and then you can access them through that child reference.