PI06 i PI06-1. Docker definitions for MSSQL and Postgres. Data seeder/generator for countries and people. Entity Framework example with variants for Postgres and MSSQL

DefensiveProgramming/Barricades/Barricades.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

DefensiveProgramming/Barricades/Course.cs

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+using System.Diagnostics;
+
+namespace Barricades;
+
+class Course(string name)
+{
+  public string Name { get; private set; } = name;
+
+  //Consider why is dictionary private variable, and why not a property!    
+  //indexer serves as a barricade
+  
+  private Dictionary<string, int> grades = new Dictionary<string, int>();
+
+  /// <summary>
+  /// Assign the new grade to the student.
+  /// Old value (if had existed) is replaced.    
+  /// </summary>
+  /// <param name="name">Student's name</param>
+  /// <returns>The student's grade or -1 if the student does not have a grade</returns>
+  /// <exception cref="System.ArgumentOutOfRangeException">Thrown if value is not valid grade [1-5]</exception>
+  public int this[string name]
+  {
+    get
+    {      
+      //what if there is no student's name in the dictionary
+      //throw exception, return special value? See error handling techniques
+      bool exists = grades.TryGetValue(name, out int grade);
+      return exists ? grade : -1;
+    }
+    set
+    {
+      if (value < 1 || value > 5)
+      {
+        throw new ArgumentOutOfRangeException($"Invalid grade {value}. It shoud be from 1 to 5");
+      }
+
+      grades[name] = value;
+    }
+  }
+
+  public double AverageGrade()
+  {
+    int sum = 0;
+    foreach (var pair in grades)
+    {
+      int grade = pair.Value;
+      Debug.Assert(grade >= 1 && grade <= 5,
+                   $"Invalid grade in dictionary {pair.Key} = {pair.Value}. This should never happens!");
+      sum += grade;
+    }
+    return grades.Count > 0 ? (double)sum / grades.Count : 0;
+  }
+}

DefensiveProgramming/Barricades/Program.cs

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+using Barricades;
+using System.Text;
+
+Console.OutputEncoding = Encoding.UTF8;
+
+Course c = new Course("PI");
+c["Pero"] = 2;
+c["Ana"] = 5;
+c["Ivan"] = 5;
+c["Marko"] = 1;
+c["Luka"] = 3;
+//c["Marija"] = -7; //should throw an exception
+Console.WriteLine("Average grade: " + c.AverageGrade());
+Console.WriteLine("Šime has grade: " + c["Šime"]); //prints -1