Say I have an object that looks like this:
{
_id: ObjectID(1234),
name: 'Corvid',
friends: [{
name: 'Magpie',
friends: [{
name: 'Raven'
}, {
name: 'Jackdaw',
friends: [{
name: Friends.ALL_FRIENDS
}]
}]
}, {
name: 'Jay'
}]
}
Essentially, what I am trying to do is, for every entry in list of friends, replace the current object with the result of Friends.findOne({ name: obj.name }).
I am easy able to iterate through the structure like so.
function populate(obj=friends) {
if (obj.friends) {
return populate(obj.friends);
}
return friends.findOne({ name: obj.name });
}
However, what I am having trouble with is replacing that object at that specific area. How would one go about doing this?
Related
For example, I have
[
{ name: "John" },
{ name: "Mike" },
{ name: "Homer" },
{ name: "Bart" },
{ name: "Dmitry" },
{ name: "Dan" }
]
How will I choose many objects with mongoose, if I use .limit(2) I will get [{ name: "John" }, { name: "Mike" }], I need to choose [{ name: "Bart" }, { name: "Dmitry" }]. In default JS this method looks like .slice(3,5). How will I do it with mongoose?
You can try something like this:
Model.find({name: {$in: ["Bart", "Dmitry"]}});
You can achieve this in mongodb by using skip(3).limit(2).
In Mongoose you can achieve this with myModel.find({}, 'name', {skip: 3, limit: 2}), you just have to insert values of skip and limit you want in third parameter of find.
Here's documentation with an example of skip and here's a link to a more popular answer of similar problem.
Edit: Note that this is a short-sighted solution, you should use something else for large or changing database.
I am currently having problems using my data in react-d3-tree. The data coming from the server is not compatible with the format that react-d3-tree accepts.
I was told that doing the process using a foreach function for every item will work, but I think that will be really slow, especially whe the data is too big.
The data (as shown in my console) right now is like this:
0: {
series: 'Fate'
type: 'Servant'
class: 'Saber',
},
1: {
series: 'Fate',
type: 'Servant'
class: 'Archer',
},
2: {
series: 'Fate',
type: 'Demi-servant'
class: 'Shielder',
}
And I want to achieve this structure:
[
{
name: 'Fate',
children: [
{
name: 'Servant',
children: [
{
name: 'Saber',
children: []
},
{
name: 'Archer',
children: []
}
]
},
{
name: 'Demi-servant',
children: [
{
name: 'Shielder',
children: []
}
]
}
]
}
]
This is only sample data, and later on, and I might be converting data with more children. Is there any npm package that can be helpful?
Nevermind, I actually found my answer.
I'll share these useful links in case anyone finds this question too.
https://www.npmjs.com/package/shape-json
https://www.npmjs.com/package/shape-array
Consider the array which I get as response from API call. what if the position of any one of the attributes gets changed and I want to get the attribute salary/id/idProperty i.e., If I am not sure about attribute position how can get its value without hard coding the array with index?
var arr = [
{
id: "alex",
idProperty: {
args: [
{
name: "alex_name"
},
{
salary: "16L"
}
]
}
},
{
id: "john",
idProperty: {
args: [
{
name: "john_name"
},
{
salary: "14L"
}
]
}
}
];
I want to update an element of an array inside mongodb's document (I am using mongoose). Schema is something like:
{
..
arr : [{
foo: Number,
bar: [String],
name: String
}]
..
}
And my query is:
SomeModel.update({
_id: "id of the document",
arr: {
$elemMatch: {
_id: "_id assigned by mongoose to array element"
}
}
}, {
'arr.$': {
name: 'new name'
}
}).exec()
It just replaces whole array element say:
{
_id: "some objectId",
name: 'old name',
foo: 0,
}
to:
{
name: 'new name'
}
what I want:
{
_id: "some objectId",
name: 'new name',
foo: 0,
}
What I am curious to know if it is possible to achieve this in single update query ? (May be there is a silly mistake in my query :P or another approach)
I would also like to do update query like so:
{
$inc: { foo: 1},
$push: { bar: "abc"}
}
If you are still struggling with the whole implementation the full application of your statement is as follows:
SomeModel.update(
{
"arr._id": "123"
},
{
"$set": { "arr.$.name": "new name" },
"$inc": { "arr.$.foo": 1},
"$push": { "arr.$.bar": "abc" }
}
)
,function(err,numAffected) {
});
So each operation is performed in turn.
How can I browse a store and find the number of records which have one attribute the same?
I have tired filterBy but there you can only enter a concrete value not an attribute
Let's say I have this records:
record1{
name: 'John'
}
record2{
name'John'
}
record3{
name:'Steve'
}
Return the records with the same name
Just loop over the collection:
var seen = {};
store.each(function(rec) {
var name = rec.get('name');
if (!seen.hasOwnProperty(name)) {
seen[name] = 0;
}
++seen[name];
});
You might also be interested by Grouping:
var myStore = Ext.create('Ext.data.Store', {
groupField: 'name',
groupDir : 'DESC'
});
myStore.getGroups(); // returns:
[
{
name: 'yellow',
children: [{
name: 'John'
}, {
name: 'John'
}]
},
{
name: 'Steve',
children: [{
name: 'Steve'
}]
}
]
Then you can count how many children there is in each group.
(More details here: http://docs.sencha.com/extjs/4.2.0/#!/api/Ext.data.Store)