We Keep Coding

javascript - JSON file use a value only if key exists

I'm retrieving an OSM Json from an overpass call, to obtain a list of features that I have to save on a database. Since the data are very different from one another (for example, some of them do have a a tag called "addr:city", and some of them not), I would like to check if a key exists, and only in that case save the corresponding value. I've found only this question but it's not my case, since I do not know a priori which keys one element will have and which not, and since I'm working with a great load of data, I really can't check the elements one by one and of course I can't write an IF for each case.
Is there a way to solve this? I was thinking something about "if key has null value, ignore it", while looping over the elements, but I don't know if something like that exists
EDIT:
This is my query:
https://overpass-api.de/api/interpreter?data=[out:json][timeout:25];(node[~%22^(tourism|historic)$%22~%22.%22](44.12419,%2012.21259,%2044.15727,%2012.27696);way[~%22^(tourism|historic)$%22~%22.%22](44.12419,%2012.21259,%2044.15727,%2012.27696););out%20center;
and this is the code I'm using to save the data on firebase:
results.elements.forEach(e=>{
var ref = firebase.database().ref('/point_of_interest/');
var key = firebase.database().ref().child('point_of_interest').push().key;
var updates = {};
var data = {
città: e.tags["addr:city"],
tipologia: e.tags["amenity"],
indirizzo: e.tags["addr:street"],
nome: e.tags["name"],
lat: e.lat,
lon: e.lon
}
updates['/point_of_interest/'+key] = data;
firebase.database().ref().update(updates);
})
"results" is the response in json format

You could use something like that:
var attrs = ["addr:city", "amenity", "addr:street", "name"];
var labels = ["città", "tipologia", "indirizzo", "nome"]
var data = { };
attrs.forEach((a, i) => {
if (e.tags[a]) { data[labels[i]] = e.tags[a]; }
});
You could even make this more dynamic, if you can query the attribute names and labels from somewhere.

Delete a field from Firestore, with a dynamic key

I am trying to delete a single field from a Document in Firestore
The Key of the field is held in a variable e.g.
var userId = "random-id-1"
In the document I have a field of members structured like this:
{
members:{
random-id-1:true,
random-id-2:true
}
}
I would like to delete random-id-1:true, but keep random-id-2:true
How is this possible without getting the entire members object and writing an updated object?
I have tried this, however I get the error: Document references must have an even number of segments
and I also tried this:
db.collection('groups').doc(this.props.groupId).set({
members: {
[userId]: firebase.firestore.FieldValue.delete()
}
},{merge: true})
However I get the error: Function DocumentReference.update() called with invalid data. FieldValue.delete() can only appear at the top level of your update data
Thanks for any help

I have managed to delete a field like this:
let userId = "this-is-my-user-id"
let groupId = "this-is-my-group-id"
db.collection('groups').doc(groupId).update({
['members.' + userId]: firebase.firestore.FieldValue.delete()
})
This is using the dot operator method described here
Please let me know if there are any alternative methods to this
Thanks

I had to import FieldValue
https://firebase.google.com/docs/firestore/manage-data/delete-data#fields
// Get the `FieldValue` object
var FieldValue = require('firebase-admin').firestore.FieldValue;
// Create a document reference
var cityRef = db.collection('cities').doc('BJ');
// Remove the 'capital' field from the document
var removeCapital = cityRef.update({
capital: FieldValue.delete()
});

Nested array into backbone model

I have the following backbone model:
var Info = Backbone.Model.extend({
urlRoot: 'http://localhost:8080/info',
defaults : {
nombre: '',
tipo : '',
telf : 0,
icono : '',
direccion:[{
direccion:'',
latitud:'',
longitud:''
}]
},
idAttribute:"_id"
});
I want to change the value of the "direccion" atribute of the array inside "direccion".
I have used the following code but is not working:
//clone the array
var direccionArray = _.clone(this.collection.get(idInfo).get('direccion'));
direccionArray.direccion = this.$('#dir-info-edit').val();
Here I obtain the array with the values changed and works fine:
console.log(direccionArray);
Now I set the array into my backbone model as follow and is not working (the model don't change) and I get the same model (changing other atributes like "nombre" or "tipo" works fine but not with the array):
this.collection.get(idInfo).set('direccion',direccionArray);
console.log(this.collection.get(idInfo));
Could someone help me please?

As stated direccion attribute of model is an array that contains object at index 0.
When you trying to do:
//clone the array
var direccionArray = _.clone(this.collection.get(idInfo).get('direccion'));
direccionArray.direccion = this.$('#dir-info-edit').val();
This will not update the direccionArray[0], which you want to update, and just will add new attribute to your array object.
What you want to do is:
direccionArray[0].direccion = this.$('#dir-info-edit').val();
Try console.dir(direccionArray) the old array and you will see the difference.
Update:
Please see this jsfiddle with the explanation of the issue. The main reason for your case can be that you are tring to get the value with jquery's val() method on an element that is not an input.

Loop through all Mongo collections and execute query

First of, I'm quite new to mongodb. Here's my question I've not been able to find a solution to.
Let's say I have 3 different collections.
mongos> show collections
collectionA
collectionB
collectionC
I want to create a script that iterates over all collections ind this database and find the last inserted timestamp in each of these collections. Here's what works inside mongos.
var last_element = db.collectionA.find().sort({_id:-1}).limit(1);
printjson(last_element.next()._id.getTimestamp());
ISODate("2014-08-28T06:45:47Z")
1. Problem (Iterate over all collections)
Is there any possibility to to sth. like.
var my_collections = show collections;
my_collections.forEach(function(current_collection){
print(current_collection);
});
Problem here, the assignment for my_collections does not work.
I get SyntaxError: Unexpected identifier. Do I need to quote the 'show' statement ? Is it even possible ?
2. Problem (storing collection in js var)
I can workaround Problem 1 by doing this:
var my_collections = ["collectionA", "collectionB", "collectionC"];
my_collections.forEach(function(current_collection){
var last_element = db.current_collection.find().sort({_id:-1}).limit(1);
print(current_collection);
printjson(last_element.next()._id.getTimestamp());
});
The last_element.next() produces the following error:
error hasNext: false at src/mongo/shell/query.js:124
It seems that last_element isn't saved correctly.
Any suggestions on what I'm doing wrong??
UPDATE
Neils answer lead me to this solution. In addition to his code I had to check if the function getTimestamp really exist. For some 'virtual' collections there seem to be no _id property.
db.getCollectionNames().forEach(function(collname) {
var last_element = db[collname].find().sort({_id:-1}).limit(1);
if(last_element.hasNext()){
var next = last_element.next();
if(next._id !== undefined && typeof next._id.getTimestamp == 'function'){
printjson(collname + " >> "+next._id.getTimestamp());
}else{
print(collname + " undefined!! (getTimestamp N/A)")
}
}
});

There is the db.getCollectionNames() helper method that does this for you. You can then implement your code:
db.getCollectionNames().forEach(function(collname) {
// find the last item in a collection
var last_element = db[collname].find().sort({_id:-1}).limit(1);
// check that it's not empty
if (last_element.hasNext()) {
// print its timestamp
printjson(last_element.next()._id.getTimestamp());
}
})
You probably also want a .hasNext() check in there to cater for possible empty collections.

Rename the collection name present in all the records using the following script:
db = db.getSiblingDB("admin");
dbs = db.runCommand({ "listDatabases": 1 }).databases;
dbs.forEach(function(database) {
db = db.getSiblingDB(database.name);
db.currentname.renameCollection("newname");
});

Length of and iterating array that is using custom properties

var profileDataCalls = [];
profileDataCalls['Profile'] = GetUserAttributesWithDataByGroup;
profileDataCalls['Address'] = GetUserAddresses;
profileDataCalls['Phone'] = GetUserPhoneNumbers;
profileDataCalls['Certs'] = GetUserCertifications;
profileDataCalls['Licenses'] = GetUserLicenses;
profileDataCalls['Notes'] = GetUserNotes;
My problem is the above JavaScript array is only a length of 0. I need an array that can be iterated over and holds the key(string) and value?

You want:
var profileDataCalls = {
'Profile' : GetUserAttributesWithDataByGroup,
'Address' : GetUserAddresses,
'Phone' : GetUserPhoneNumbers,
'Certs' : GetUserCertifications,
'Licenses' :GetUserLicenses,
'Notes' : GetUserNotes
};
Then you can access the values with, for example, profileDataCalls.profile or profileDataCalls[profile] (to retrieve whatever value is represented by the variable GetUserAttributesWithDataByGroup)
To iterate through the object, use:
for (var property in profileDataCalls) {
if (profileDataCalls.hasOwnProperty(property)) {
console.log(property + ': ' + profileDataCalls[property));
}
}

Javascript doesnt have associative arrays per say , what you are doing is adding properties to the Array instance. IE doint something like
profileDataCalls.Notes = GetUserNotes;
so you cant really use length to know how many properties your array would have.
now if your issue is iterating over your object properties , you dont need an array , just use an object :
profileDataCalls = {}
then use a for in loop to iterate over the keys :
for(var i in profileDataCalls ){
// i is a key as a string
if(profileDataCalls.hasOwnProperty(i)){
//do something with profileDataCalls[i] value , or i the key
}
}
it you have different requirements then explain it.
now the tricky part is profileDataCalls[0]="something" would be valid for an object({}), you would create a property only available through the lookup (obj[0]) syntax since it is not a valid variable name for javascript.
other "crazy stuffs" :
o={}
o[0xFFF]="foo"
// gives something like Object {4095:"foo"} in the console

Actually it also works like this:
var profileDataCalls = [{
Profile: GetUserAttributesWithDataByGroup(),
Address: GetUserAddresses(),
Phone: GetUserPhoneNumbers(),
Certs: GetUserCertifications(),
Licenses: GetUserLicenses(),
Notes: GetUserNotes()
}];
Then you can access the values with, for example, profileDataCalls[0].profile or profileDataCalls[0]["profile"].
To iterate through the object, you can use:
for (key in profileDataCalls[0]) {
console.log(profileDataCalls[0][key]);
}
Since this is an associative array, I never understood why people are saying its not possible in Javascript...in JS, everything is possible.
Even more, you could expand this array easily like this:
var profileDataCalls = [{
Profile: GetUserAttributesWithDataByGroup(),
Address: GetUserAddresses(),
Phone: GetUserPhoneNumbers(),
Certs: GetUserCertifications(),
Licenses:GetUserLicenses(),
Notes: GetUserNotes()
}{
Profile: GetUserAttributesWithDataByGroup(),
Address: GetUserAddresses(),
Phone: GetUserPhoneNumbers(),
Certs: GetUserCertifications(),
Licenses: GetUserLicenses(),
Notes: GetUserNotes()
}];
And access the array entries with profileDataCalls[0]["profile"] or profileDataCalls[1]["profile"] respectively.

What you want is an object:
Try
var profileDataCalls = new Object();
then reference your data as you do already.