dotnet

EntityFramework.Exceptions 3.1.1 - Support for Entity Framework Core 3 and Improved API

In the previous article I introduced EntityFramework.Exceptions, a library which simplifies handling exceptions in Entity Framework Core but the library had one important limitation. In order to use it you had to inherit your custom DbContext from ExceptionProcessorContextBase class. This means that if you wanted to use some other base class for your DbContext you were out of luck. The latest version of the library solves this issue by

Introducing EntityFramework.Exceptions

When using Entity Framework Core for data access all database exceptions are wrapped in DbUpdateException. If you need to know whether the exception was caused by a unique constraint, value being too long or value missing for a required column you need to dig into the concrete DbException subclass instance and check the error number to determine the exact cause. EntityFramework.Exceptions simplifies this by handling all the database specific details and throwing different exceptions for different cases. All you have to do is

Building Expression Evaluator with Expression Trees in C# – Improving the Api

This post is part of a series about building a simple mathematical expression evaluator. For previous posts and full source code see Table of Contents. Introduction In previous part we added support for variables but it has a big disadvantage: values of the variables are bound by position and not by name. This means that you should pass values for the variables in the same order as they appear in the expression. For example the following test will fail:

Using Reactive Extensions for Streaming Data from Database

You have probably heard about Reactive Extensions, a library from Microsoft that greatly simplifies working with asynchronous data streams and allows to query them with Linq operators. There are many different scenarios where using rx results in a much more simple and flexible code. This post demonstrates how to use reactive extensions for loading data from database asynchronously in chunks.

Building Expression Evaluator with Expression Trees in C# – Table of Contents

This is table of contents for Building Expression Evaluator with Expression Trees in C# series. We are going to build a simple mathematical expression evaluator in C# using expression trees. The library supports simple expressions such as 2.5+5.9, 17.89-2.47+7.16, 5/2/2+1.5*3+4.58, expressions with parentheses (((9-6/2)*2-4)/2-6-1)/(2+24/(2+4)) and expressions with variables: var a = 6; var b = 4.32m; var c = 24.15m; Assert.That(engine.Evaluate("(((9-a/2)*2-b)/2-a-1)/(2+c/(2+4))", a, b, c), Is.EqualTo((((9 - a / 2) * 2 - b) / 2 - a - 1) / (2 + c / (2 + 4)))); At the end of the series full source code will be available at github and the library will be published to NuGet.

How to Get Elevated Process Path in .Net

As you know retrieving process path in .Net is quite straightforward. For example if you have process instance someProcess you can get the process path by accessing someProcess.MainModule.FileName However for elevated processes the previous code snippet throws Win32Exception.

Bugs in System.Diagnostics.Process Class

While working on an application which makes use of Process class I found several bugs which occur in special conditions. More specifically accessing StartTime or HasExited properties causes a Win32Exception with NativeErrorCode equal to five. This indicates that the exception is caused by not having enough rights to retrieve the required information. The exception occurs under the following conditions: