Skip to main content

Solution - A challenge with Promises from Java Script

Some days ago I had a challenge for you about a code that had a bug.
var bingUrl = new Windows.Foundation.Uri("http://www.bing.com");
Windows.Storage.ApplicationData.current.temporaryFolder.createFileAsync("myFile.txt")
.then(function (myFile) {
var backgroundDownloader = new Windows.Networking.BackgroundTransfer.BackgroundDownloader();
var currentDownload = backgroundDownloader.createDownload(bingUrl, myFile);
currentDownload.startAsync();
})
.then(
function (result) {
return displayOkayStatus(result);
});

...
function displayOkayStatus(result){
return "Complete" + result.toString();
}
In the following code the result parameter from displayOkayStatus is undefined all the time.
The cause of this problem is related to how we use promises. If we use a promise in another promise we should return the promise all the time. In this way we can create a chain. Without this, the JavaScript will not wait our async code to end execute and will call our callback. It is recommended to use then when we have intermediate stage of operation and done for the final call (we cannot have something like .done().done()).
To have a more readable code it is recommended to have calls to functions in a done or in a then and not a definition of a method. In this way any person will be able to read our code more easily.
var bingUrl = new Windows.Foundation.Uri("http://www.bing.com");
Windows.Storage.ApplicationData.current.temporaryFolder.createFileAsync("myFile.txt")
.then(function (myFile) {
var backgroundDownloader = new Windows.Networking.BackgroundTransfer.BackgroundDownloader();
var currentDownload = backgroundDownloader.createDownload(bingUrl, myFile);
return currentDownload.startAsync();
})
.then(
function (result) {
return displayOkayStatus(result);
});

...
function displayOkayStatus(result){
return "Complete" + result.toString();
}

Comments

Post a Comment

Popular posts from this blog

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

Run native .NET application in Docker (.NET Framework 4.6.2)

Scope
The main scope of this post is to see how we can run a legacy application written in .NET Framework in Docker.

Context
First of all, let’s define what is a legacy application in our context. By a legacy application we understand an application that runs .NET Framework 3.5 or higher in a production environment where we don’t have any more the people or documentation that would help us to understand what is happening behind the scene.
In this scenarios, you might want to migrate the current solution from a standard environment to Docker. There are many advantages for such a migration, like:

Continuous DeploymentTestingIsolationSecurity at container levelVersioning ControlEnvironment Standardization
Until now, we didn’t had the possibility to run a .NET application in Docker. With .NET Core, there was support for .NET Core in Docker, but migration from a full .NET framework to .NET Core can be costly and even impossible. Not only because of lack of features, but also because once you…