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JavaScript Ember with Sails

I'm working with EmberJS and SailsJS. Now I've been asked to make a statistics page and handle the filtering process in the SailsJS.
I have a model for departments and another model for requests the relationship between these models is (request belongsTo department). For some reason my manager prevented me to make a (hasMany) relationship.
Now what I want to do is to loop through all the departments and store them in new Object, inside that loop I want to loop through all the requests by Using Request.count({where : { department : department.id }}) and get the number of requests for each department in the departments Array Of Object.
I tried to do it as I explained but the problem is when I log the department inside the request loop it gives me the result as I imagined but when I add (.id) it shows me 'undefined'.
Here is my code:
Department.find().then((departments) => {
report.departments = departments;
Request.count({ department : departments.id}).exec(function countMe(err, count) {
console.log(count);
})
})
PS: if there's any other approach for this task please tell me, I'm kind of a beginner.

Your departments object in the .then callback is an array of department objects. To get an id you'd need to do something like departments[0].id.
I might not recommend using .count because that means a separate trip to the database for each department. Sails waterline may have some way for you to count up Requests grouped by department id, but just to get a steamroller working example, I would first just get everything and do some processing in your code:
Department.find().then((departments) => {
Request.find().then((requests) => {
var requestCounts = {}; // we'll store the counts in this object
for (var idx = 0; idx < requests.length; idx++) {
if (!requestCounts[requests[idx].department]) {
requestCounts[requests[idx].department] = 0;
}
requestCounts[requests[idx].department]++;
}
// use requestCounts...
});
});
Creating a separate object like that may not be what you want to do, but something like this should serve whatever purpose you have. Notice, the code I wrote did not require finding all the department objects, but whatever you are doing likely will...
If you're interested in efficiency, then once you get this working, you can see if there is some way you can query the database to directly get the counts you want instead of this in-code processing. But I would start with something simple like this.
EDIT:
It sounds like you may be able to use something like:
Request.find().groupBy('department').sum('count').exec(function (err, results){
console.log(results);
});
But I'm finding conflicting reports on whether this works with sails-mongo, so take this as a "maybe this will work" recommendation.

I assume Request has a property department which is an ObjectId related to departments.
The quick one is to correct the following:
the 2nd line does not make sense as reports is not used
do
let departmentIds = _.map(departments, 'id');
and use departmentIds in the count query object
However, you are anyway finding all departments in the initial query, I would assume you count all the Requests anyway. Finding the departments first only makes sense in case you have query object there limiting the number of returned departments.
In addition, if you know the departmentIds in question you might not need to query them. Otherwise you might use a projection to just return the departmentIds instead of all the properties of all the departments

update, instead of replace, list used for ng-repeat

How it is
I have an array of objects called vm.queued_messages (vm is set to this in my controller), and vm.queued_messages is used in ng-repeat to display a list of div's.
When I make an API call which changes the underlying model in the database, I have the API call return a fresh list of queued messages, and in my controller I set the variable vm.queued_messages to that new value, that fresh list of queued messages.
vm.queued_messages = data; // data is the full list of new message objects
The problem
This "full replacement" of vm.queued_messages worked exactly as I wanted, at first. But what I didn't think about was the fact that even objects in that list which had no changes to any properties were leaving and new objects were taking their place. This made no different to the display because the new objects had identical keys and values, they were technically different objects, and thus the div's were secretly leaving and entering every time. THIS MEANS THERE ARE MANY UNWANTED .ng-enter's AND .ng-leave's OCCURRING, which came to my attention when I tried to apply an animation to these div's when they entered or left. I would expect a single div to do the .ng-leave animation on some click, but suddenly a bunch of them did!
My solution attempt
I made a function softRefreshObjectList which updates the keys and values (as well as any entirely new objects, or now absent objects) of an existing list to match those of a new list, WITHOUT REPLACING THE OBJECTS, AS TO MAINTAIN THEIR IDENTITY. I matched objects between the new list and old list by their _id field.
softRefreshObjectList: function(oldObjs, newObjs) {
var resultingObjList = [];
var oldObjsIdMap = {};
_.each(oldObjs, function(obj) {
oldObjsIdMap[obj._id] = obj;
});
_.each(newObjs, function(newObj) {
var correspondingOldObj = oldObjsIdMap[newObj._id];
if (correspondingOldObj) {
// clear out the old obj and put in the keys/values from the new obj
for (var key in correspondingOldObj) delete correspondingOldObj[key];
for (var key in newObj) correspondingOldObj[key] = newObj[key];
resultingObjList.push(correspondingOldObj);
} else {
resultingObjList.push(newObj);
};
});
return resultingObjList;
}
which works for certain things, but with other ng-repeat lists I get odd behavior, I believe because of the delete's and values of the objects being references to other controller variables. Before continuing down this rabbit hole, I want to make this post in case I'm thinking about this wrong, or there's something I'm missing.
My question
Is there a more appropriate way to handle this case, which would either make it easier to handle, or bypass my issue altogether?
Perhaps a way to signal to Angular that these objects are identified by their _id instead of their reference, so that it doesn't make them leave and enter as long as the _id doesn't change.
Or perhaps a better softRefreshObjectList function which iterates through the objects differently, if there's something fishy about how I'm doing it.

Thanks to Petr's comment, I now know about track by for ng-repeat. It's where you can specify a field in your elements that "identifies" that element, so that angular can know when that element really is leaving or entering. In my case, that field was _id, and adding track by message._id to my ng-repeat (ng-repeat="message in ctrl.queued_messages track by message._id") solved my issue perfectly.
Docs here. Search for track by.

CouchDB - Variables in map function

I am quite new to CouchDB and have a very basic question:
Is there any possibility to pass a variable from the client into the map function, e.g.:
function (doc, params) {
if (doc.property > params.property) emit(doc, null);
}
Thanks for your help,
Christian

While Dominic's answer is true, the example in the actual question can probably be implemented as a map function with an appropriate key and a query that includes a startkey. So if you want the functionality that you show in your example you should change your view to this:
function(doc) {
if( doc.property )
emit( doc.property, null);
}
And then your query would become:
/db_name/_design/view_doc/_view/view_name?startkey="property_param"&include_docs=true
Which would give you what your example suggests you're after.
This is the key (puns are funny) to working with CouchDB: create views that allow you to select subsets of the view based on the key using either key, keys or some combination of startkey and/or endkey

No, map functions are supposed to create indexes that always take the same input and yield the same output so they can remain incremental. (and fast)
If you need to do some sort of filtering on the results of a view, consider using a _list function, as that can take client-supplied querystring variables and use them in their transformation.

Backbone multi-collection global search

I'm playing around with the idea of creating a global search that allows me to find any model in any of a number of collections by any of the model's attributes. For example:
I have the following collections:
Users
Applications
Roles
I don't know ahead of time what attributes each User, Applicaion and Role will have but for illustration purposes lets say I have:
User.name
User.last_name
User.email
Application.title
Application.description
Role.name
Role.description
Now, lets say I create a model called Site with a method called search. I want Site.search(term) to search through all the items in each collection where term matches any of the attributes. In essence, a global model search.
How would you suggest I approach this? I can brute-force it by iterating through all the collections' models and each model's attributes but that seems bloated and inefficient.
Any suggestions?
/// A few minutes later...
Here's a bit of code I tried just now:
find: function(query) {
var results = {}; // variable to hold the results
// iterate over the collections
_.each(["users", "applications", "roles"], _.bind(function(collection){
// I want the result to be grouped by type of model so I add arrays to the results object
if ( !_.isUndefined(results[collection]) || !_.isArray(results[collection]) ) {
results[collection] = [];
}
// iterate over the collection's models
_.each(this.get(collection).models, function(model){
// iterate over each model's attributes
_.each(model.attributes, function(value){
// for now I'm only considering string searches
if (_.isString(value)) {
// see if `query` is in the attribute's string/value
if (value.indexOf(query) > -1) {
// if so, push it into the result's collection arrray
results[collection].push(model);
}
};
});
});
// a little cleanup
results[collection] = _.compact(results[collection]);
// remove empty arrays
if (results[collection].length < 1) {
delete results[collection];
}
},this));
// return the results
return results;
}
This yields the expected result and I suppose it works fine but it bothers me that I'm iterating over three arrays. there may not be another solution but I have a feeling there is. If anyone can suggest one, thank you! Meanwhile I'll keep researching.
Thank you!

I would strongly discourage you from doing this, unless you have a very limited set of data and performance is not really a problem for you.
Iteration over everything is a no-no if you want to perform search. Search engines index data and make the process feasible. It is hard to build search, and there is no client-side library that does that effectively.
Which is why everybody is doing searching on the server. There exist easy (or sort of) to use search engines such as solr or the more recent and my personal preference elasticsearch. Presumably you already store your models/collections on the server, it should be trivial to also index them. Then searching becomes a question of making a REST call from your client.

KnockoutJS: Update/Insert data to a viewModel using mapping

I've been trying to figure this out for quite some time now. I couldn't find anything that addresses this problem, but please correct me if I'm wrong.
The problem:
I have data from a JSON API comming in, with an nested array/object structure. I use mapping to initially fill the model with my data. To update this, I want to extend the model if new data arrives, or update the existing data.
As far as I found out, the mapping option key, should do this trick for me, but I might have misunderstood the functionality of the mapping options.
I've boiled down the problem to be represented by this example:
var userMapping = {
key: function(item) {
return ko.utils.unwrapObservable(item.id);
}
};
// JSON call replaced with values
var viewModel = {
users: ko.mapping.fromJS([], userMapping)
};
// Should insert new - new ID?
ko.mapping.fromJS([{"id":1,"name":"Foo"}, {"id":2,"name":"Bar"}], userMapping, viewModel.users);
// Should only update ID#1 - same ID?
ko.mapping.fromJS([{"id":1,"name":"Bat"}], userMapping, viewModel.users);
// Should insert new - New ID?
ko.mapping.fromJS([{"id":3,"name":"New"}, {"id":4,"name":"New"}], userMapping, viewModel.users);
ko.applyBindings(viewModel);​
Fiddle: http://jsfiddle.net/mikaelbr/gDjA7/
As you can see, the first line inserts the data. All good. But when I try to update, it replaces the content. The same for the third mapping; it replaces the content, instead of extening it.
Am I using it wrong? Should I try to extend the content "manually" before using mapping?
Edit Solution:
I solved this case by having a second helper array storing all current models. On new data i extended this array, and updated the view model to contain the accumulated items.
On update (In my case a WebSocket message), I looped through the models, changed the contents of the item in question, and used method valueHasMutated() to give notice of changed value to the Knockout lib.

From looking at your example code the mapping plugin is behaving exactly as I would expect it to. When you call fromJS on a collection you are effectively telling the mapping plugin this is the new contents of that collection. For example:
On the second line, How could it know whether you were updating or whether you had simply removed id:2?
I can't find any mention of a suitable method that treats the data as simply an update, although you could add one. Mapped arrays come with some helpful methods such as mappedIndexOf to help you find particular items. If you receive an update data set simply loop through it, find the item and update it with a mapping.fromJS call to that particular item. This can easily be generalized into reusable method.

You can use ko.mapping.updateFromJS() to update existing values. However, it does not add new values so that would be a problem in your instance. Take a look at the link below for more details.
Using updateFromJS is replacing values when it should be adding them

Yes, you should first collect all data into a list or array and then apply the mapping to that list. Otherwise you are going to overwrite the values in your viewModel.