DbContext model diagram requires a parameterless contstructor

[lamelyan]

Trying to generate a .dgml model diagram. When I select the option, I get an error that DbContext must have a parameterless constructor.

System.ArgumentException: Error:
Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type 'CampaignContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
 ---> System.MissingMethodException: No parameterless constructor defined for type 'Repository.CampaignContext'.
   at System.RuntimeType.CreateInstanceDefaultCtorSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean fillCache)
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, Boolean wrapExceptions)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic, Boolean wrapExceptions)
   at System.Activator.CreateInstance(Type type)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_3.<FindContextTypes>b__13()
   --- End of inner exception stack trace ---
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.<>c__DisplayClass13_3.<FindContextTypes>b__13()
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
   at ReverseEngineer20.EfCoreModelBuilder.BuildResult(String outputPath, Boolean generateDdl) in C:\Code\EFCorePowerTools\src\GUI\efpt\EFCoreModelBuilder.cs:line 39
   at ReverseEngineer20.Program.Main(String[] args) in C:\Code\EFCorePowerTools\src\GUI\efpt\Program.cs:line 44

Parameter name: processResult
   at EFCorePowerTools.Handlers.ModelAnalyzerHandler.Generate(String outputPath, Project project, GenerationType generationType) in C:\projects\efcorepowertools\src\GUI\EFCorePowerTools\Handlers\ModelAnalyzerHandler.cs:line 72

The parameterless constructor also requires that I set a connection to the database. This is probably because I use that connection string in the

  protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseMySql(_connectionString);
        }

I would think that 'Add DbContext Model Diagram' wouldn't require connection to the database or parameterless constructor but just look at the model configuration.

The link provided in the exception message does say that the tools require a parameterless constructor but I wonder if there a workaround for this? I don't want to introduce code (parameterless constructor with a connection) that isn't required for my application.

Steps to reproduce

1. Right-click on a project that contains DbContext
2. Select Add DbContext Model Diagram

Further technical details

EF Core Power Tools version: 2.3.92.0

Database engine:
MySQL
Using package - Pomelo EF for MySql

Visual Studio version: (e.g. Visual Studio 2019 16.4.2)

[ErikEJ]

Did you read the link in the error message?

[ErikEJ]

I really dont think there is anything I can do here...