Category Archives: Web Development

Breaking the Internet

eShopOnContainers – No parameterless constructor defined for type dbcontext

Hi everyone,

Another eShopOnContainers post. Today I was setting up migrations and ran into the following error:

Found DbContext ‘CatalogContext’.
Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type ‘CatalogContext’. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
—> System.MissingMethodException: No parameterless constructor defined for type ‘Catalog.Api.Infrastructure.CatalogContext’.
at System.RuntimeType.CreateInstanceDefaultCtorSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean fillCache)

This turned out to be because I was missing the following from my CatalogContext:

public class CatalogContextDesignFactory : IDesignTimeDbContextFactory
{
public CatalogContext CreateDbContext(string[] args)
{
var optionsBuilder = new DbContextOptionsBuilder()
.UseSqlServer(“Server=.;Initial Catalog=Microsoft.eShopOnContainers.Services.CatalogDb;Integrated Security=true”);

return new CatalogContext(optionsBuilder.Options);
}
}

‘DatabaseFacade’ does not contain a definition for ‘Migrate’ and no accessible extension method ‘Migrate’… – eShopOnContainers

Hi everyone,

I’ve been going through Microsoft’s eShopOnContainers repo and replicating it as a small test project to learn microservices. While adding the WebHost Customization project I ran into the following error: 

Severity Code Description Project File Line Suppression State
Error CS1061 ‘DatabaseFacade’ does not contain a definition for ‘Migrate’ and no accessible extension method ‘Migrate’ accepting a first argument of type ‘DatabaseFacade’ could be found (are you missing a using directive or an assembly reference?) WebHost.Customization … N/A

This turned out to be a fairly simple fix. All that’s required is the following package (I installed via Nuget):

Microsoft.EntityFrameworkCore.SqlServer

Thanks to the following stackoverflow post for the info: https://stackoverflow.com/a/57606203/522859

Return URL is missing path – Azure AD B2C

Hi everyone,

Just a small issue I’ve hit while implementing Azure AD B2C. After logging in Azure has been routing me to the base path instead of including the controller.

The solution to this turned out to be pretty straight-forward. All URLS apparently need to be including in the reply URLs of your Azure AD B2C application.

Just add a new row with the entire url to yours and it should start working immediately.

Thanks,
Chris

Azure AD B2C – Unauthorized

Hi everyone,

I’ve been mucking around with Azure AD B2C. It seems like a pretty good substitute for AWS Cognito that I’ve used previously.

While following the Microsoft sample tutorials I ran into an “unauthorized” error. A value was being returned but no access token was provided.

This seems to be indicative of an issue with scopes. In my case, I’d excluded a trailing slash on the ApiIdentifier url in the TaskWebApp web.config.

This seems to be a fairly common configuration issue. The following stackoverflow post pointed me in the right direction:

https://stackoverflow.com/a/49304044/522859

Relevant tutorial article can be found here: https://docs.microsoft.com/en-au/azure/active-directory-b2c/active-directory-b2c-tutorials-web-api?tabs=applications

Prevent Hot-Chocolate Schema Polling from Spamming Logs – GraphQL

Hi everyone,

I’m currently toying around with GraphQL on with HotChocolate on .NET Core Microservices. After implementing logging I ran into a bit of a problem every time I opened the GraphQL playground.

While observing my logs I noticed that an almost continuous stream of Schema logs were appearing which made it fairly difficult to track down any legitimate errors. The solution to this turned out to be fairly simple – playground offers both a polling enabled and polling frequency setting that can be configured locally:

polling

I simply disabled this for testing, and then increased it to 30s once I’d migrated my logs to seq.

The logging implementation itself was based off the following example: https://chillicream.com/blog/2019/03/19/logging-with-hotchocolate

Thanks,
Chris

error : “Timestamp” is not defined. – .net core and gRPC

Hi everyone,

I’m currently testing out gRPC with .NET Core and hit the following error when attempting to add a timestamp field to my proto file:

error : “Timestamp” is not defined.

My proto file was as follows:

syntax = “proto3”;
import “google/protobuf/timestamp.proto”;

option csharp_namespace = “publisher_api”;

package Weather;

// The weather forecast service definition
service Weather {

// Gets weather forecast
rpc Forecast(WeatherForecastRequest) returns (WeatherForecastResponse);
}

// The request message
message WeatherForecastRequest {

}

// The response message
message WeatherForecastResponse {
timestamp date = 1;
int32 temperatureC = 2;
int32 temperatureF = 3;
string summary = 4;
}

The solution was to fully qualify the timestamp namespace:


message WeatherForecastResponse {
google.protobuf.Timestamp date = 1;
int32 temperatureC = 2;
int32 temperatureF = 3;
string summary = 4;
}

Also ensure that you’ve added the protobuff package:

dotnet add package Google.Protobuf

See the following repo for a full example: https://github.com/Buzzology/microservicesDockerRabbitMQ

Current .NET SDK does not support targeting .NET Core 3.0 – Microservices

Hi everyone,

I’m currently learning microservices with .Net Core. As part of this I’ve been following one of Microsoft’s tutorials: https://dotnet.microsoft.com/learn/aspnet/microservice-tutorial

It has all been pretty straight forward, however I hit an error when attempting to run docker build:

RUN dotnet restore
—> Running in 734e82e92c23
/usr/share/dotnet/sdk/2.2.207/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(137,5): error NETSDK1045: The current .NET SDK does not support targeting .NET Core 3.0. Either target .NET Core 2.2 or lower, or use a version of the .NET SDK that supports .NET Core 3.0. [/src/myMicroservice.csproj]
The command ‘/bin/sh -c dotnet restore’ returned a non-zero code: 1

Updating the Dockerfile references seems to have resolved the issue. I replaced each occurrence of 2.2 with 3.0 and re-ran the following command:

docker build -t microservice .

My complete docker file was as follows:

# https://dotnet.microsoft.com/learn/aspnet/microservice-tutorial/docker-file
FROM mcr.microsoft.com/dotnet/core/sdk:3.0 AS build
WORKDIR /src
COPY myMicroservice.csproj .
RUN dotnet restore
COPY . .
RUN dotnet publish -c release -o /app

FROM mcr.microsoft.com/dotnet/core/aspnet:3.0
WORKDIR /app
COPY –from=build /app .
ENTRYPOINT [“dotnet”, “myMicroservice.dll”]

Full source available here: https://github.com/Buzzology/myMicroservice