This post is continuation of the series. If you do not have Postgres on your machine or sample data, you can read Installing PostgreSQL and Loading Sample Data post first.
There are functions like
date_gt to compare date types.
select * from payment where date_gt(payment_date::date, '2007-04-01'::date);
You can use
date_part to get a part of datetime.
select amount, payment_date, date_part('quarter', payment_date) as quarter, date_part('year', payment_date) as year, concat('Q', date_part('quarter', payment_date), '-', date_part('year', payment_date)) as display_quarter from payment;
generate_series(start, stop, step) generates a series of values, from
stop with a step size of
step. We need a function like
f(x) to get the value. If we use a negative number as
step, it will be decreasing.
select x, md5(random()::text) from generate_series(100, 0, -5) as f(x); select x from generate_series('2001-10-01'::TIMESTAMP, '2002-10-01'::TIMESTAMP, '10 days') as f(x);
As an experienced and certified .NET Developer, Postgres made my attention. I will tell about its reasons in another post.
I will write my notes about Postgres in this series. We will start with installing and loading sample data to our database in this post and we will have a result like below at the end.
First, download PostgreSQL database from PostgreSQL Downloads page to install. I use Windows so I chose Windows installer but you can use another operating system and also to develop because we can code ASP.NET Core Web Application in different operating systems.
We can use an ASP.NET Core Web Application template to create our Web API. We will use Npgsql, a PostgreSQL database provider for Entity Framework Core. Install its package from NuGet with the command below.
PM> Install-Package Npgsql.EntityFrameworkCore.PostgreSQL
If you already have a Postgres database, add its connection string to appsettings.json as PostgreConnection or you can read Installing PostgreSQL and Loading Sample Data post in this series to install a database on your machine.
Write a model for film table of the sample data. Important part is Postgres is case sensitive here, so we need to define column and table names explicitly. Also EF wants to know the identity column of the table.
Deutschland 83 is a series about the political conflicts between West and East germany. In the third episode which is called “Atlantic Lion” of the first season, the underdeveloped technology of East Germany doesn’t let the officers to read the floppy disc of a NATO official.
They finally acquire an IBM Model 5155 computer from the West but they find the disc is encoded. When they insert the disc, it starts to print out number with 5 digits as 6 columns and unknown rows of matris. After that, they start to decode it.
On the next scene, we see a code block which generates random numbers on the screen with 3 for loops. As we can see from that, the number of rows is 64 and the matris is all random. Also there are some mistyped letters with
Syntax error below.
C# now has some new features with the release of Visual Studio 2017. Those features focused on code simplification, performance and data consumption. I prepared a simple console application to show them in one file.
out variables lets us to declare variables inline. I you don’t want to declare a variable for any of out variable you can use
Constant, Type or Var patterns can be used in if statements and you can declare new inline variables as in
Switch has biggest improvements. You can switch, not just primitive types, any type you want. Patterns can be used in case clauses which can have additional conditions with
Content Delivery Network (CDN) cache needs to be refreshed after deploying a Web UI project. I developed a custom step which runs a PowerShell script on Octopus, a well-known deployment tool in .NET eco-system, to trigger purge method of the CDN server which is Medianova CDN and added it to community step library.
Now, you can see the details of Medianova - Purge Step on Octopus Deploy Library and install it from the community step templates page of the Octopus dashboard.
PS: We should add the version parameter to the static files. This process will not renew the browser cache.
I prepared and gave a presentation about .NET Core to my colleagues last month.
You could find the source code of the ASP.NET Core demonstration project on github.com/olcay/aspnetcoresample repository.
More posts about .NET Core are coming…
The app helps to memorize anything with its simple UX. It has the same simplicty while creating a deck of flashcards. We have published some decks as A Clockwork Engineer which you can find on https://tiny.cards/users/olcaybayram. First, you should download the app to commence and it is free but it is only for iOS right now.
- HTTP Verbs & Status Codes
- Git Commands
So we want to deploy it to Heroku cloud platform to see its cross-platform capabilites.
Heroku app engine runs the dotnet cli with the parameters below.
cd /app/heroku_output && dotnet ./Libton.dll --server.urls http://+:54372
server.urls parameter sets the port variable which can be different everytime. The default value is 5000 in ASP.NET Core and our application doesn’t have the capability to read the command line arguments so it won’t set and listen the specified port.
In order to give this capability to our application, we could add the reference of Microsoft.Extensions.Configuration.CommandLine via NuGet Package Manager.
Now, we could convert the command line arguments to configuration settings and use them on the web host builder on Main method of the Program class.
Finally, the Program.cs file will look like this;
Burak Tungut - Book author
Gökhan Gökalp - Book author