"Mastering the art of linking AJAX calls in Angular

Question

"Mastering the art of linking AJAX calls in Angular

I need to make 2 AJAX calls, with the second call dependent on the result of the first one. Currently, I am handling it in this way:

Service.getA(car).then(function(carInfo) {
    if (carInfo.success) {
        Service.getB(carInfo.number).then(function(holderInfo) {
            console.log(holderInfo);
        });
    }
});

Service:

getA: function(car) {
    return Server.execute({
        method: 'GET',
        url: 'a/a',
        params: {
            car: car
        },
    }).then(function (carInfo) {
        return carInfo;
    });
},

The getB method is similar - just a different URL and parameters. I am new to Angular and would like to refactor this code using promises and defers (as Google suggests that the code will be more elegant). How can I achieve that?

javascript ajax angularjs promise

Answer 1

Answer №1

Your approach to chaining ajax calls is common, but there are ways to simplify it for better readability:

  Service.getA(car).then(function(carInfo) {
     Service.getB(carInfo.number).then(function(holderInfo) {
        console.log(holderInfo);
     });
  });

To handle errors more effectively, consider having your server return a Bad Request 400 status and chain the .error() callback instead of checking for success based on the success property.

Regarding Cerbrus' observation, using $q.all([promise1, promise2]) will execute promises in parallel rather than sequentially dependent on each other.

In your getA method, simply return the promise like this:

 getA: function(car) {
    return Server.execute({
       method: 'GET',
       url: 'a/a',
       params: {
           car: car
       },
    });
  }

If you need to include additional callbacks within the service, you can structure it like so:

 getA: function(car) {
    return Server.execute({
        method: 'GET',
        url: 'a/a',
        params: {
            car: car
        },
    }).then(function (carInfo) {
        //handle success

    }, function () {
        //handle error
    });
},

Answer 2

Your approach to chaining ajax calls is common, but there are ways to simplify it for better readability:

  Service.getA(car).then(function(carInfo) {
     Service.getB(carInfo.number).then(function(holderInfo) {
        console.log(holderInfo);
     });
  });

To handle errors more effectively, consider having your server return a Bad Request 400 status and chain the .error() callback instead of checking for success based on the success property.

Regarding Cerbrus' observation, using $q.all([promise1, promise2]) will execute promises in parallel rather than sequentially dependent on each other.

In your getA method, simply return the promise like this:

 getA: function(car) {
    return Server.execute({
       method: 'GET',
       url: 'a/a',
       params: {
           car: car
       },
    });
  }

If you need to include additional callbacks within the service, you can structure it like so:

 getA: function(car) {
    return Server.execute({
        method: 'GET',
        url: 'a/a',
        params: {
            car: car
        },
    }).then(function (carInfo) {
        //handle success

    }, function () {
        //handle error
    });
},

Answer 3

Answer №2

After comparing the two and noting that they are almost identical except for the URL and parameters, my recommendation would be to use the following function:

fetchData : function(apiURL, dataParams) {
    return Backend.execute({
        method: 'GET',
        url: apiURL,
        params: dataParams,
    });
},

Usage example:

DataService.fetchData('example/api', requestData).then(function(responseData) {
    if (responseData.success) {
        DataService.fetchData('another/api', responseData.id).then(function(finalData) {
            console.log(finalData);
        });
    }
});

Answer 4

After comparing the two and noting that they are almost identical except for the URL and parameters, my recommendation would be to use the following function:

fetchData : function(apiURL, dataParams) {
    return Backend.execute({
        method: 'GET',
        url: apiURL,
        params: dataParams,
    });
},

Usage example:

DataService.fetchData('example/api', requestData).then(function(responseData) {
    if (responseData.success) {
        DataService.fetchData('another/api', responseData.id).then(function(finalData) {
            console.log(finalData);
        });
    }
});

"Mastering the art of linking AJAX calls in Angular

Answer №1

Answer №2

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