Wednesday, April 25, 2018

ASP.Net Core 2 with Postgresql on Linux Part 10: Program, Startup, appsetting.json, etc.

In Part I, I discussed the rationale for porting a ASP.Net Core 2 app to my Linux system replacing SQL Server with Postgresql and place it on Heroku. 

With Part II, we transferred the SQL Server data to Postgres.

In Part III, I create the ASP.Net MVC Core 2.x app, from which we will proceed, and get Entity Framework Core installed.

Then in Part IV, I look at the configuration differences between the ASP.Net MVC app that uses SQL Server and the new app, in preparation of porting the old app to use Postgresql.

Part V, we compared the differences in both the projects' structures and ported the existing project code, starting with the data model layer, to the new project. In addition to this, we got the jquery.countdown jquery plugin installed, that is used to implement a JavaScript timer. More on that in a later article. Finally, we used the dotnet ef dbcontext scaffold command that builds a DbContext and entity types for out Postgresql database. And, oh yes, we added the project to github, which frankly should have been done day one.

In Part VI, we got the NUnit testing framework in place 
in order to test both the new and future code.

Part VII, saw the Service layer setup along with its unit tests.

In Part VIII we imported the Controller classes from the existing app and setup unit tests for them.

Then in Part IX, we will migrated the Razor (*.cshtml) files as well as the associated JavaScript, Cascading Style Sheet (CSS), and image files from the existing app.

In this post, the Program.cs and Startup.cs files as well as the appsettings.json and project files (*.csproj) content will be migrated and then updated from utilizing SQL Server to accessing Postgresql for data.

Here is the compare of those root files:

Since these files are specific to the application, a simple copy and replace cannot be made. Examining the content we see that existing app (on the left) we see the bower.json file .bowerrc, which are part of the Bower Package Manager. This was addressed earlier in Part V where discussed the recommended move from Bower to Yarn

First, let's look at the appsettings.json files. After moving the Logging and Appsettings object settings, the remaining difference was the database connection strings, which specify the database platform used.

Next, when comparing the two apps' project files you see several differences. 

A few the differences are specific residual settings needed when the existing app was moved from .Net Core 1.x to 2.0. For example, the following setting:

was need when UserSecrets 1.0.0, that required the existence of the project.json. When moved to a csproj file the above was needed. See this:

AssetTargetFallback below was set so that with the move to .NET Core 2.0, any NuGet package that is compatible with .NET Framework 4.6.1 or higher can be used without additional configuration.

The other settings are/were necessary for the current app's functionality.

The final file to consider is the Startup.cs file.

The differences here are the between the SQL Server and Postgresql DbContextOptionsBuilder object that is used in the lambda expression as options:
options => options.UseNpgsql

The DbContextOptionsBuilder object, "provides a simple API surface for configuring DbContextOptions. Databases (and other extensions) typically define extension methods on this object that allow you to configure the database connection (and other options) to be used for a context."

Ok. Now we are ready to run the new MVC .Net Core 2.0 app.

Browsing to the https://localhost:5000 URL and we see the initial page.

In the next and final post in this series, we will deploy this app to Heroku via Docker.

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