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enter image description herei am making simple http request to doGet method of servlet to fetch data from table. bellow is my code.

var myApp = angular.module('myApp', []);

myApp.controller('myController', function ($scope,$http) {


$scope.getDataFromServer = function() { 

            $http    
({         
    method:'GET',
    url:'jasoncontroller'    
}).success(function(data, status, headers, config){ 
                $scope.sqldata = data;                    

                console.log("executing");
                $scope.$watch('sqldata',function(newValue,oldValue){
                    console.info('changed');
                    console.log('new : ' + newValue);
                    console.log('old : ' + oldValue);
                    console.log('watch end');                    
                });            


}).error(function(data, status, headers, config){});

    };

});

servlet doGet method

    protected void doGet(HttpServletRequest request, HttpServletResponse           response) throws ServletException, IOException {     
       System.out.println("Executing get");     
    getSqlData sql = new getSqlData();          
    Gson gson = new GsonBuilder().serializeNulls().create();        
    String tabname="saleq315";                      
    String json = gson.toJson(sql.gettabledata(tabname));       
    response.setContentType("application/json");
    response.getWriter().write(json);
    System.out.println("data sent");        
}

Whenever i click to fetch data it never get me new data once i change the table name in tabname="saleq315"; after multiple click table data refresh. and when i log this to console i see http request getting executed mulpliple times. If you see the image attached, i changed the table name and click to get the data,

first click - same table data --> console log one entry
seconds click - same table data --> console log one entry
third click - got new data --> console log 5 entries.
 Not sure what is happening here.

[![enter image description here][1]][1]
Nomad
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    From the documentation : 'The watchExpression is called on every call to $digest() and should return the value that will be watched. (watchExpression should not change its value when executed multiple times with the same input because **it may be executed multiple times by $digest()**. That is, watchExpression should be **idempotent**'. That means you have to check equality of `oldValue` and `newValue` before doing something. By the way I hope you are not calling `getDataFromServer` multiple times because you will create multiple watchers. – LG_ Sep 08 '15 at 08:50
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    You should create the $watch only once and outside the callback of http call. – LG_ Sep 08 '15 at 08:55

0 Answers0