CODEWITHSUNDEEP
javascriptangularjsfilter
Kimchi Man
Kimchi Man

Reputation: 1171

Filtering object based on the range of year

I want to filter object within some year range.

The object I have looks like this:

students = [ {studentId: 1, 
              studentName: 'Alex',
              studentClass: 1,
              studentBirth: 1345262400000},

             {studentId: 2,
              studentName: 'Bob',
              studentClass: 1,
              studentBirth: 1345608000000},
              ...
             ];

And I want to find some students that birth year > 1994 && birth year < 2000. Also, I want to narrow down based on student's class.

I wrote code like this:

var targetStudent = {};
targetStudent['studentClass'] = 1;
students = $filter('filter')(students, targetStudent);

With above code, I can find students whose class is 1, but I don't know how to filter out based on year.

I could write something like:

students = $filter('filter')(students, function(student) {
    if(new Date(student.studentBirth).getFullYear() < 2000 && new Date(student.studentBirth).getFullYear() > 1994)
        return true;
    else
        return false;
});

But I want to create an object to find students. Is it possible?

Upvotes: 1

Views: 59

Answers (1)

csbarnes
csbarnes

Reputation: 1893

You are actually very close to answering your own question. When using a custom filter function you can return the object and you will get an array of objects back.

students = $filter('filter')(students, function(student) {
    if(new Date(student.studentBirth).getFullYear() < 2000 && new Date(student.studentBirth).getFullYear() > 1994) {
        return student;
    }
});

Unless this is only being used once, and even then, I'd go with something more reusable:

$scope.getStudentsForRange = function(studentList, fromYear, toYear) {
    return $filter('filter')(studentList, function(student) {
        var studentBirthYear = new Date(student.studentBirth).getFullYear();

        if(studentBirthYear < toYear && studentBirthYear > fromYear) {
            return student;
        }
    };
};

Which you can use like so: $scope.getStudentsForRange(students, 1994, 2000)

This has the added bonus of only creating a new Date object once, keeping things DRY.

EDIT

It sounds like you want a custom filter.

angular.module('rootApp', []).filter('studentFilter', function() {
    return function(students, studentFilter) {
        return $filter('filter')(students, function(student) {
            var birthYear = new Date(student.studentBirth).getFullYear();

            if(student.studentClass === studentFilter.studentClass && birthYear < studentFilter.toYear && studentFilter.birthYear > fromYear) {
                return student;
            }
        };
    };
});

Which can be used in a template: {{ students | studentFilter:{studentClass: 1, fromYear: 1994, toYear: 2000} }}.

Or inside a controller/directive:

var targetStudent = {
    studentClass: 1,
    fromYear: 1994,
    toYear: 2000
};

students = $filter('studentFilter')(students, targetStudent);

Upvotes: 1

Related Questions