Google Geocoder Asynchronous Issue

问题

I believe that I have having a timing issue with geocoder results. See a snippet of code below.

I am basically performing a geocode and getting the result. I then pass the result to a server side method via the jQuery AJAX call. Finally the result of the method returns a JSON object. Based on the result I may or may not perform a second geocode. This is where the problem lies.

You can see I have a variable hasResult defaulted to false, and is toggled to true when a valid result has been determined. In all cases this works perfect, except when the need for a second geocode occurs. The geocode happens successfully and the code executes, but the final hasResult check still returns false. How can this be?

var hasResult = false;            
geocoder.geocode({ "address": address }, function (results, status) {
    if (status == google.maps.GeocoderStatus.OK) {
        $.ajax({
            url: "URL",
            type: "POST",
            dataType: "json",
            data: results
            contentType: "application/json; charset=utf-8",
            success: function (result) {
                        if (result.Valid) {
                            hasResult = false;
                            //Some other code, works perfect                            
                        } else {
                            geocoder.geocode({ "address": result.ValidRequest }, function (resultsNew, statusNew) {
                                if (statusNew == google.maps.GeocoderStatus.OK) {
                                    hasResult = false; 
                                    //Some other code, works perfect
                                }
                            });
                        }
                    });
                });
            }
        });
    }
});

if (hasResult == true) {
    alert('Success');
} else {
    alert('Fail');
}

Thanks

回答1:

This is because you check the value of hasResult before you get the results from the server. This happens, because the request is asynchrounous. You should use callbacks instead.

Edit:

Try this (this is only a mockup and is not tested, change it to improve readability, pass successOrFailure as a parameter/callback etc.):

var hasResult = false;            

var successOrFailure = function(hasResult){
    if (hasResult == true) {
        alert('Success');
    } else {
        alert('Fail');
    }
};

geocoder.geocode({ "address": address }, function (results, status) {
    if (status == google.maps.GeocoderStatus.OK) {
        $.ajax({
            url: "URL",
            type: "POST",
            dataType: "json",
            data: results
            contentType: "application/json; charset=utf-8",
            success: function (result) {
                        if (result.Valid) {
                            hasResult = false;
                            successOrFailure(hasResult);
                            //Some other code, works perfect                            
                        } else {
                            geocoder.geocode({ "address": result.ValidRequest }, function (resultsNew, statusNew) {
                                if (statusNew == google.maps.GeocoderStatus.OK) {
                                    hasResult = false;
                                    successOrFailure(hasResult); 
                                    //Some other code, works perfect
                                }
                            });
                        }
                    });
                });
            }
        });
    }
});

来源：https://stackoverflow.com/questions/6129733/google-geocoder-asynchronous-issue

标签

jquery

asynchronous

google-geocoder