Working with Equals() and GetHashCode() to compare your objects in C#

In general these interfaces and methods are good to implement when working with comparing objects of the same type in C#:

Interfaces:
System.IEquatable<T> – strongly typed implementation
IComparable<T> – strongly typed implementation

Override methods:
An override of Object.Equals(Object).
An override of Object.GetHashCode().
An override of Object.ToString() is usually a good idea.
Operator overloads for operator == and operator !=.

General rule of GetHashCode():
If two objects is equal then their hashvalues should be the same.
E.g.:
If Equals == true then
x.GetHashCode() == y.GetHashCode()
GetHashCode() is frequently used by collections like Dictionary<Key, Value> and HashSet<T>

Links:
Guidelines for Overloading Equals() and Operator == (C# Programming Guide)
https://msdn.microsoft.com/en-us/library/ms173147.aspx

Visual Studio – Snippet for Arrange Act Assert comments

I like to comment my tests following the arrange, act, assert pattern.

E.g.
//Arrange
//Act
//Assert

Here is a snippet you can add to “your” snippets folder in Visual Studio 2019:
(or use menu Tools -> Code snippet manager to find your correct path to add to).
Filename: C:\Users\andreasp\Documents\Visual Studio 2019\Code Snippets\Visual C#\My Code Snippets\testmethodcomment_act_arrange_assert.snippet

<?xml version="1.0" encoding="utf-8"?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
  <CodeSnippet Format="1.0.0">
    <Header>
      <SnippetTypes>
        <SnippetType>Expansion</SnippetType>
      </SnippetTypes>
      <Title>Test Method Comment - Act Arrange Assert</Title>
      <Shortcut>testaaa</Shortcut>
      <Description>Code snippet for a test method structure comments. Act arrange assert</Description>
    </Header>
    <Snippet>
      <Code Language="csharp">
    <![CDATA[//Arrange
    $end$
    
    //Act 
    
    //Assert
    ]]></Code>
    </Snippet>
  </CodeSnippet>
</CodeSnippets>

Restart Visual Studio.

Usage:
Inside testmethod, type:
taaa [tab]
The 3 comments will be inserted.

c# – Ignore XML namespace when modelbinding in asp net core web api

So, in order to be able to modelbind XML to a class without taking namespaces into consideration I created new InputFormatter. And I use XmlTextReader in order to ignore namespaces. Microsoft recommends to use XmlReader rather than XmlTextReader. But since XmlTextReader is there still (in .Net 6.0 Preview 3) I’ll use it for now.

Simply create an inputformatter that inherits from XmlSerializerInputFormatter like so:

public class XmlNoNameSpaceInputFormatter : XmlSerializerInputFormatter
{
    private const string ContentType = "application/xml";
    public XmlNoNameSpaceInputFormatter(MvcOptions options) : base(options)
    {
        SupportedMediaTypes.Add(ContentType);
    }

    public override bool CanRead(InputFormatterContext context)
    {
        var contentType = context.HttpContext.Request.ContentType;
        return contentType.StartsWith(ContentType);
    }

    public override async Task<InputFormatterResult> ReadRequestBodyAsync(InputFormatterContext context)
    {
        var type = GetSerializableType(context.ModelType);
        var request = context.HttpContext.Request;

        using (var reader = new StreamReader(request.Body))
        {
            var content = await reader.ReadToEndAsync();
            Stream s = new MemoryStream(Encoding.UTF8.GetBytes(content));

            XmlTextReader rdr = new XmlTextReader(s);
            rdr.Namespaces = false;
            var serializer = new XmlSerializer(type);
            var result = serializer.Deserialize(rdr);
            return await InputFormatterResult.SuccessAsync(result);
        }
    }
}

Then add it to the inputformatters like so to startup.cs:

        services.AddControllers(o => 
        {
            o.InputFormatters.Add(new XmlNoNameSpaceInputFormatter(o));
        })
        .AddXmlSerializerFormatters();

Now we can modelbind Person or any other class no matter if there is namespaces or not in the incoming XML. Thanks to @yiyi-you

Source: c# – Ignore XML namespace when modelbinding in asp net core web api – Stack Overflow

c# – LINQ’s Distinct() on a particular property

EDIT: This is now part of MoreLINQ.
What you need is a “distinct-by” effectively. I don’t believe it’s part of LINQ as it stands, although it’s fairly easy to write:

public static class EnumerableExtensions
{
public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
HashSet<TKey> seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
}
}
}

Source: c# – LINQ’s Distinct() on a particular property – Stack Overflow

c# – sgen.exe fails during build – Stack Overflow

After adding a new 3rd party reference to a project and then building for Release configuration I got this error (not present when in debug build):
Error Could not load file or assembly ‘x’ or one of its dependencies. The system cannot find the file specified. SGEN  

Here is a solution that worked for me:

If you are having this problem while building your VS.NET project in Release mode here is the solution: Go to the project properties and click on the Build tab and set the value of the “Generate Serialization Assembly” dropdown to “Off”. Sgen.exe is “The XML Serializer Generator creates an XML serialization assembly for types in a specified assembly in order to improve the startup performance of a XmlSerializer when it serializes or deserializes objects of the specified types.” (MSDN)

Source: c# – sgen.exe fails during build – Stack Overflow

BenchmarkDotNet

Benchmarking is really hard (especially microbenchmarking), you can easily make a mistake during performance measurements. BenchmarkDotNet will protect you from the common pitfalls (even for experienced developers) because it does all the dirty work for you: it generates an isolated project per each benchmark method, does several launches of this project, run multiple iterations of the method (include warm-up), and so on. Usually, you even shouldn’t care about a number of iterations because BenchmarkDotNet chooses it automatically to achieve the requested level of precision.

Source: Home – BenchmarkDotNet Documentation

LiteDB – A .NET NoSQL Document Store in a single data file – CodeProject

A simple, fast and free embedded .NET NoSQL Document Store in a single data file. Inspired on MongoDB, supports collections, POCO classes, Bson Documents, indexes, stream data, ACID transactions and LINQ expressions.

Introduction

This article is an overview about my database project LiteDB – a small, fast and free embedded .NET NoSQL Document Store for .NET in a single datafile – and now it’s on new version 2.0

Source: LiteDB – A .NET NoSQL Document Store in a single data file – CodeProject