Rashim's Blog

Archive for August 2014


Getting instant response on the error in an input gives the user a better familiarity on how to precise it. Validation service is very handy to do that, and almost all controls have their own validation service. But sometime we require developing our own validation service to notify user that what input it might require, and it is very easy to inject our own validation to any control using Angular JS. Today I am going to introduce you with such custom validation technique using angular JS and its feature sets.

When we work with the date field we might be in situation to validate a date range that is to say that one date should be less than other date or vice versa. To implement such functionality I have written a small directive which provides this competence to us.

The following directive could be used to check that the date is lower than other date,

 
app.directive('dateLowerThan', ["$filter", function ($filter) {
    return {
        require: 'ngModel',
        link: function (scope, elm, attrs, ctrl) {           
            var validateDateRange = function (inputValue) {
                var fromDate = $filter('date')(inputValue, 'short');
                var toDate = $filter('date')(attrs.dateLowerThan, 'short');
                var isValid = isValidDateRange(fromDate, toDate);
                ctrl.$setValidity('dateLowerThan', isValid);
                return inputValue;
            };

            ctrl.$parsers.unshift(validateDateRange);
            ctrl.$formatters.push(validateDateRange);
            attrs.$observe('dateLowerThan', function () {
                validateDateRange(ctrl.$viewValue);
            });
        }
    };
}]);
 

Here we see that there are two new things: $parser and $formatters. While we need to write a custom validation we have to write a directive which would be dependent on the ng-model directive, and $parsers and $formatters is used to hook up the custom validation logic. When the value in the control is modified the functions added to $parsers are called, and the functions added to $formatters are invoked when the model is modified in the code.The $formatters are useful when there is a possibility of the value getting changed from the code. You will get an better idea if you go through this link

Same way, the following directive could be used to check whether a date is greater than other,

 
app.directive('dateGreaterThan', ["$filter", function ($filter) {
    return {
        require: 'ngModel',
        link: function (scope, elm, attrs, ctrl) {            
            var validateDateRange = function (inputValue) {
                var fromDate = $filter('date')(attrs.dateGreaterThan, 'short');
                var toDate = $filter('date')(inputValue, 'short');
                var isValid = isValidDateRange(fromDate, toDate);
                ctrl.$setValidity('dateGreaterThan', isValid);
                return inputValue;
            };

            ctrl.$parsers.unshift(validateDateRange);
            ctrl.$formatters.push(validateDateRange);
            attrs.$observe('dateGreaterThan', function () {
                validateDateRange(ctrl.$viewValue);

            });
        }
    };
}]);
 

The utility function that has been used here,

 
var isValidDate = function (dateStr) {
    if (dateStr == undefined)
        return false;
    var dateTime = Date.parse(dateStr);

    if (isNaN(dateTime)) {
        return false;
    }
    return true;
};

var getDateDifference = function (fromDate, toDate) {
    return Date.parse(toDate) - Date.parse(fromDate);
};

var isValidDateRange = function (fromDate, toDate) {
    if (fromDate == "" || toDate == "")
        return true;
    if (isValidDate(fromDate) == false) {
        return false;
    }
    if (isValidDate(toDate) == true) {
        var days = getDateDifference(fromDate, toDate);
        if (days < 0) {
            return false;
        }
    }
    return true;
};
 

And finally the module and controller,

 
var app = angular.module("Main_app", ['ui.bootstrap']);

app.controller("MainController", ["$scope", function ($scope) {
    var currentDate = new Date();
    $scope.FromDate = new Date();
    $scope.ToDate = currentDate.setDate(currentDate.getDate() + 1);
    $scope.dateOptions = {
        formatYear: 'yy',
        startingDay: 1
    };
    $scope.formats = ['dd-MMMM-yyyy', 'yyyy/MM/dd', 'dd.MM.yyyy', 'shortDate'];
    $scope.format = $scope.formats[0];
}]);
 

Files that you need to include,

angular.min.js

jquery.min.js

jquery-ui.min.js

ui-bootstrap.min.js

ui-bootstrap-tpls.min.js

And in html body you could use this directive like the way,


<div ng-controller="MainController">
        <form name="frmDateRange" novalidate>
            <div style="height: 400px">
                <div class="col-md-12 marginBottom15">
                    <label class="col-md-3 control-label">
                        From date
                    </label>
                    <div class="col-md-5">
                        <input type="text"
                            name="fromDate"
                            class="form-control"
                            datepicker-popup="{{format}}"
                            ng-model="FromDate"
                            datepicker-options="dateOptions"
                               required 
                            date-lower-than="{{ToDate| date:'short'}}" />
                    </div>
                    <div class="col-md-4 offset0">
                        <span 
                            ng-show="frmDateRange.fromDate.$error.required && 
                            !frmDateRange.fromDate.$pristine">
                            Invalid or Empty from date
                        </span>
                        <span
                            ng-show="frmDateRange.fromDate.$error.dateLowerThan">
                            From date must be lower than To date
                        </span>
                    </div>
                </div>
                <div class="col-md-12 marginBottom15">
                    <label class="col-md-3 control-label">
                        To date
                    </label>
                    <div class="col-md-5">
                        <input type="text"
                            name="endDate"
                            class="form-control"
                            datepicker-popup="{{format}}"
                            ng-model="ToDate"
                            min="FromDate"
                            datepicker-options="dateOptions"
                               required 
                            date-greater-than="{{FromDate| date:'short'}}" />
                    </div>
                    <div class="col-md-4 offset0">
                        <span 
                            ng-show="frmDateRange.endDate.$error.required 
                            && !frmDateRange.endDate.$pristine">
                            Invalid or Empty to date
                        </span>
                        <span 
                            ng-show="frmDateRange.endDate.$error.dateGreaterThan">
                            To date must be greater than from date
                        </span>
                    </div>
                </div>
            </div>
        </form>
    </div>
 

That’s it. Now play with this. The source code is available here.

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Almost all web based projects, where location/address is included, we might require mapping service to show the exact location or street view on the page. Thanks to Google to give us such amazing service application, yes I am talking about Google Maps which offers street maps and street view perspective and many more. To get the map rendered in the web page using Angular JS is pretty easy and straight forward. I am going to show you how we can do this,

For this is so, I have created a directive so that I could reuse it throughout the application as an html tag. To locate the area, we might put its Latitude and Longitude or we might put just a valid address. The following directive could be used while we have the latitude and longitude for a particular area,


app.directive('areaBasedGoogleMap', function () {
    return {
        restrict: "A",
        template: "<div id='areaMap'></div>",
        scope: {           
            area: "=",
            zoom: "="
        },
        controller: function ($scope) {
            var mapOptions;
            var map;           
            var marker;

            var initialize = function () {                                
                mapOptions = {
                    zoom: $scope.zoom,
                    center: new google.maps.LatLng(40.0000, -98.0000),
                    mapTypeId: google.maps.MapTypeId.TERRAIN
                };
                map = new google.maps.Map
(document.getElementById('areaMap'), mapOptions); }; var createMarker = function (area) { var position = new google.maps.LatLng
(area.Latitude, area.Longitude); map.setCenter(position); marker = new google.maps.Marker({ map: map, position: position, title: area.Name }); }; $scope.$watch("area", function (area) { if (area != undefined) { createMarker(area); } }); initialize(); }, }; });

And this directive might be used while we have a valid address,


app.directive('addressBasedGoogleMap', function () {
    return {
        restrict: "A",
        template: "<div id='addressMap'></div>",
        scope: {
            address: "=",
            zoom: "="
        },
        controller: function ($scope) {
            var geocoder;
            var latlng;
            var map;
            var marker;
            var initialize = function () {
                geocoder = new google.maps.Geocoder();
                latlng = new google.maps.LatLng(-34.397, 150.644);
                var mapOptions = {
                    zoom: $scope.zoom,
                    center: latlng,
                    mapTypeId: google.maps.MapTypeId.ROADMAP
                };
                map = new google.maps.Map
(document.getElementById('addressMap'), mapOptions); }; var markAdressToMap = function () { geocoder.geocode({ 'address': $scope.address },
function (results, status)
{ if (status == google.maps.GeocoderStatus.OK) { map.setCenter(results[0].geometry.location); marker = new google.maps.Marker({ map: map, position: results[0].geometry.location }); } }); }; $scope.$watch("address", function () { if ($scope.address != undefined) { markAdressToMap(); } }); initialize(); }, }; });

And in html we can use these directives like the way,

<div address-based-google-map address="Adress" zoom="16"></div>
<div area-based-google-map area="Area" zoom="8"></div>

Finally Module and Controller definition,


var app = angular.module("Main_app", []);

app.controller("MainController", ["$scope", 
function MainController($scope) 
{    
    $scope.Adress = "American University,4400 Massachusetts Ave NW,Washington, DC 20016";
    $scope.Area = { 
                    Name: "Melbourne", 
                    Latitude: -37.8140000, 
                    Longitude: 144.9633200 
                  };
}]);

One more thing, you need to include following JS file to your html page,


angular.js
https://maps.googleapis.com/maps/api/js?sensor=false 

And the style,


 #areaMap, #addressMap
  {
    height: 400px;
    width: 400px;
    margin: 10px;
    padding: 10px;
  }

Very easy stuff but effective enough!!! Download Source Code


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