Map/Reduce in mongodb

map-reduce.js

var mapStaff = function() {
    var values = {
        department: this.department,
        grade: this.grade,
        role: this.role,
        gender: this.gender,
        preferredName: this.preferredName,
        loginName: this.loginName,
        hireDate: this.hireDate,
        totalExperience: this.totalExperience,
        twExperience: this.twExperience,
        assignable: this.assignable,
        homeOffice: this.homeOffice,
        workingOffice: this.workingOffice
    };

    emit(this.employeeId, values);
}


var mapSkill = function() {
    var values = {skills: this.skills};
    emit(this.employeeId, values);
}

var reduce = function(k, values) {
    var result = {};
    values.forEach(function(value) {
        var field;
        for (field in value) {
            if (value.hasOwnProperty(field)) {
                result[field] = value[field];
            }
        }
    });
    return result;
};

db.staff.mapReduce(mapStaff, reduce, {"out": {"reduce": "staff_skills"}});
db.skills.mapReduce(mapSkill, reduce, {"out": {"reduce": "staff_skills"}});
db.staff_skills.find().pretty();

map-reduce.md

purpose

I have a collection which contains items in the following structure:

{
	"_id" : ObjectId("55efa44a23588e5686f045e7"),
	"gender" : "Male",
	"preferredName" : "Alan Turning",
	"hireDate" : "2013-06-04",
	"totalExperience" : 4.27,
	"employeeId" : "00001"
}

and also I have another collection like this:

{
	"_id" : ObjectId("55efd19123588e5686f054b7"),
	"skills" : [ ],
	"employeeId" : "00001"
}

and I want to merge those two collection as :

{
	"_id" : ObjectId("55efa44a23588e5686f045e7"),
	"gender" : "Male",
	"preferredName" : "Alan Turning",
	"hireDate" : "2013-06-04",
	"totalExperience" : 4.27,
	"employeeId" : "00001",
	"skills": []
}

in file map-reduce.js, I defined two map function and one reduce function to do this, the result is putting into staff_skills collection.