Identity Server: Introduction

In the SPA based sample applications, this blog has used so far user authentication has either been completely ignored in order to keep the examples simpler or the sites have used ASP.NET Core’s built in identity to encapsulate the whole SPA. In this post (or series of posts) I am going to share what I learn along the way of creating an Angular (2+) application that utilizes ASP.NET Core as its host/API/backend.

This post isn’t going to cover any code it is just going to be a lot of the information I gathered in the process of learning more about Identity Server.

Identity Server

According to their docs IdentityServer4 is an OpenID Connect and OAuth 2.0 framework for ASP.NET Core which enables Authentication as a Service, Single Sign-on, API Access Control and a Federation Gateway.

Obviously, that covers a lot of scenarios. The two that I am interested in are Authentication as a Service and the API Access Control which has driven my research which means that the other aspects of IdentityServer4 will not be included.

Official Samples

The IdentityServer GitHub account has a samples repo that contains a ton of examples. I have found the quickstart area of the repo to be the most helpful when starting out.

Based on all the quickstarts samples it looks like a typical setup involves a minimum of three projects. One for the API, one for the client and one for Identity Server. As you go through the samples the number of projects increase, but that is because of a wider range of scenarios that the sample is trying to cover.

References for learning

Damienbod has a whole series of blog posts related to IdentityServer4 and code to go along with it which can be found here. As a side note if you are interested in ASP.NET Core and you aren’t following damienbo you should be he has a ton of great content.

Blog posts
Videos

Identity Server Alternatives

Identity Server isn’t the only way to go there is a number of Software as a Service options that cover a lot of same scenarios. The following are some examples.

Auth0 – Check out the .NET Core related blogs by Jerrie Pelser
Stormpath
Amazon Cognito

Wrapping up

Obviously, I didn’t get a lot covered on how to actually do something with IdentityServer, but I wanted to share my starting point. This is an area I am going to continue digging it to and sharing information about as I learn more.

If you have any resources in this area please leave a comment below.

Entity Framework Core with SQLite Migration Limitations

This is part of what has turned into a series on Entity Framework Core with SQLite. The other parts can be found below.

Entity Framework Core with SQLite
Entity Framework Core Errors Using Add-Migration
Entity Framework Core with SQLite Scaffolding

The starting point of the code for this post can be found here.

Migration Limitations when using SQLite

SQLite’s ALTER TABLE is limited which in turn limits what Entity Framework Core can do via a migration. The official docs on the subject can be found here. These limitations are on the Entity Framework Team’s list of issues as an open enhancement and can be tracked here.

As long as you are just adding new tables or columns you would never notice the limitation, but if you have spelling problems like I do then the need to rename a column can be important. Thankfully things like ReSpeller (link is to the pro page, but a free version is available in ReSharpers extension manager) help with my spelling issues.

Unsupported example with a column rename

As an example of how to handle a migration that isn’t supported, we are going to rename the State property of the Contact class to Subregion.

Rename property on the model

Open the Contact class which can be found in the Models directory and make the following change.

Add a migration

With the property name change using the following command in the Package Manager Console to create a new migration.

Which produces the following migration class.

Error trying to apply the migration

As expected when an attempt to apply the above migration results in the following exception.

System.NotSupportedException: SQLite does not support this migration operation (‘RenameColumnOperation’). For more information, see http://go.microsoft.com/fwlink/?LinkId=723262.

Modify migration to manually rename the column

Searching for how to rename a column in SQLite will turn up a lot of results including this from the official docs and answers like this on StackOverflow. The gist of the how to do a rename is to create a new table with the desired schema, copy the data from the original table, drop the old table, and finally rename the new table to match the original name.

Now knowing the process the migration above can be modified to apply SQL directly instead of using Entity Framework Core to generate the SQL. This can be done by using the Sql function of the MigrationBuilder class. The following is the resulting migration.

You will notice that I didn’t bother doing the Down function, but the same idea would apply when trying to undo a migration. SQLiteStudio or similar tools can be used to generate the SQL above if SQL isn’t something you want to deal with.

Fix other references to the renamed field

This isn’t really the topic of this post, but I wanted to throw in a reminder that after a rename like this there are places that will need to be updated that the tooling may not have picked up. For example, make sure all your views are using the new column as well as any bind statements in your controllers.

Wrapping up

The first time I hit the need to rename a column and it resulted in an exception it was extremely frustrating. Over time as I learned what the tooling around SQLite provides it has become less of an issue. I look forward to seeing what the Entity Framework team does in the future around this issue. The finished code can be found here.

Entity Framework Core with SQLite Scaffolding

This is the third in what is turning into a series of post about using SQLite with Entity Framework Core. This post is going to cover adding a migration, scaffolding a controller and related views, and a few things that are harder to do using SQLite. The following are the first two post.

Entity Framework Core with SQLite
Entity Framework Core Errors Using Add-Migration

Adding Model, DbContext, Controller, and Views

If you have any experience with Entity Framework Core or have read any of my past entries on the subject this section is going to repeat some of the same information, but I am including it so someone who is looking for a full example will have it.

Model

In the Models folder add a Contact class similar the following.

DbContext

In the Data folder add a ContactsDbContext that inherits from DbContext. The following is an example that auto applies migrations to a database, if you don’t need that functionality it can be dropped out.

Now that the application has a model and a related DbContext the following can be used to add a migration that will create a Contacts in the SQLite database. Run from the Package Manager console.

Add-Migration is a Powershell command to add a migration (surprise!), AddContacts is the name of the migration and -Context ContactsDbContext is an argument that lets the command know which  DbConext to use. The Context is only needed if your application has more than one DbContext.

Controller and Views

With the above complete Visual Studio provides some tooling that makes it very fast to create a controller with views for listing, adding, editing, and deleting items. To begin right-click on the Controllers folder and select Add > New Scaffolded Item.

Select the MVC Controller with views, using Entity Framework option and click Add.

On the next dialog use the drop downs to select a model class and a data context class. Then verify the controller name and click add.

When the process completes the following items will have been added to your project.

Add to nav bar

To add a link to the new section of the app to the nav bar open the _Layout.cshtml in the Views/Shared/ directory. The following is the section of the file that needs to be changed to add an item to the nav bar.

Specifically, the following line was added to provide access to the contact list page.

Wrapping up

With the above, the application will be runnable. The code for this post can be found here. The next post in this series will cover the limitations of migrations when using SQLite with Entity Framework Core.

 

Entity Framework Core Errors Using Add-Migration

I started off trying to expand my sample from last week’s post and hit some issues when trying to add a migration for a new DbContext.

The Setup

I added the following DbContext that only has one DbSet and auto applies migrations in the constructor.

The command

Using Visual Studio’s Package Manager Console I ran the following command.

Error 1 – No parameterless constructor

The above command resulted in the following error.

No parameterless constructor was found on ‘ContactsDbContext’. Either add a parameterless constructor to ‘ContactsDbContext’ or add an implementation of ‘IDbContextFactory<ContactsDbContext>’ in the same assembly as ‘ContactsDbContext’.

I read the first sentence and added a parameterless constructor to  ContactsDbContext. I did think it was strange that a parameterless constructor wasn’t required the other contexts I had written in the past, but the error said to add a parameterless constructor so that is what I did.

Error 2 – System.InvalidOperationException: No database provider has been configured for this DbContext

Now having a parameterless constructor I ran the Add-Migration command again and was greeted with the following error.

System.InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

The second error forced me to step back and think more about what the problem was as it didn’t have an action I could take as the first sentence, which is, of course, my fault for not fully digesting what the error was saying.

The fix

The bit I was missing was the fact that I hadn’t added the following to the  ConfigureServices function of the project’s  Startup class.

With the above added I removed the parameterless constructor from  ContactsDbContext and was able to successfully run the add migration command again.

Wrapping up

The moral of the story is to actually read the full error message before running off and trying to fix the problem. The second error message saying “using AddDbContext on the application service provider” is what triggered me to head in the right direction.

This was also a good reminder that tools like the ones used by Add-Migration can/do compile the project they are being used on in order to have enough context to perform their tasks.

Entity Framework Core with SQLite

All the applications used as examples for ASP.NET Core and Entity Framework Core from this site so far used database running SQL Server/SQL Express. In addition to the Microsoft-based SQL databases, Entity Framework Core has support for a number of other database providers. This post is going to look at using SQLite. A full list of the support database providers can be found here.

Starting point

Using Visual Studio 2017 I started with a new ASP.NET Core project using Individual User Accounts which ensured all the Entity Framework Core bits were present. The template in RC 4 used packages based on the Core 1.0.3 which I upgraded to 1.1.0. The project at this point can be found here.

Just a side note this project was created when Visual Studio 2017 was at the RC 4 stage. This code associated with this post will be updated when Visual Studio 2017 is released.

Naming warning

As you will be able to see with the structure of the solution I started this work using the project name SQLite. With this project name, it was impossible to get the SQLite package to install. If you see something like the following renaming your project should get you running.

This issue is where I found out what the problem was.

Add SQLite Packages

Right-click on the project file and click Manage NuGet Packages.

Select Browse and in the search box enter “Microsoft.EntityFramework.Sqlite” and install the two packages that are found.

Remove SqlServer Packages

While still in the Manage NuGet Packages screen click on the Installed tab. Select and uninstall the following packages.

Configuration changes

Open appsettings.json and in the ConnectionStrings delete the line for DefaultConnection. Next, in the same section add a line for a SQLite connection string. The following is the result.

The above will expect the database file to be in the same location as the application is running. For a debug build the database file can be found in the \bin\Debug\netcoreapp1.0\ directory of the project.

Startup changes

The final location to change is in the ConfigureServices function of the Startup class. The following shows the addition of the application DB context before and after the changes.

Wrapping up

The application is now runnable using SQLite as its backing data store. At this point, the only thing using data access is related to identity. The first time an attempt is made to access the database you may be prompted to apply migrations.

I have been using SQLite Studio to view the data in my database if you have that need outside of the application it does a good job.

The code in its final state can be found here.

ASP.NET Core Conversion to csproj with Visual Studio 2017 and update to 1.1.1

On March 7th Visual Studio 2017 was released bring the ASP.NET Core tools preview. ASP.NET Core 1.1.1 was also released. This post is going to cover converting the project from my MailGun post from being project.json based to csproj as well as migrating from the project from ASP.NET Core 1.0.2 to 1.1.1. Here is the project as it stood before I made any changes.

Visual Studio 2017

The first step is to get a version of Visual Studio 2017 (VS 2017) installed. The download page can be found here. Make sure to grab the community edition if you are looking for a free fully-featured IDE option. Check out this blog post from Microsoft on the many new features Visual Studio 2017 brings.

The installer for VS 2017 has changed a lot from previous versions. The way it works now is you select the workload you use and it only installs the bit it has to to keep the size of install down. The following is a screen shot from my install. I have a lot more workloads checked that is needed for just an ASP.NET Core application. At a minimum make sure the “ASP.NET and web development” workload gets installed. If you are interested in cross-platform development scroll to the bottom and also check “.NET Core cross-platform development”.

Project conversion

When you open the solution in VS 2017 it will prompt you to do a one-way upgrade.

After the conversion is complete a migration report will open. Below is mine. I had no issues, but if there were any this report should give you some idea of how they should be addressed.

As part of the conversion process, the following file changes happened.

That is all there is to the conversion. The tooling takes care of it all and your project should keep work just as before. The sample project post conversion can be found here.

Migration from 1.0.x to 1.1.1

The migration is almost as simple as the project conversion. In the solution explorer right click on the project to be migrated and select Properties.

Find the Target framework selection and select  .NETCoreApp 1.1. Then save your solution.

Next, open the NuGet Package Manager. It can be by right click on the project and selecting Manage NuGet Packages or from the Tools > NuGet Package Manager > Manage NuGet Packages for Solution.

Select the Updates tab and update all the related packages to 1.1.1 and click the Update button.

If you want a specific list of all the package changes check out the associated commit.

The only other change needed is in the constructor of the  Startup class.

Wrapping up

After all the changes above your solution will be on the latest released bits. Having been following releases since beta 4 I can tell you this is one of the easiest migration so far. I may be partial, but .NET and Microsoft seem to be getting better and better over the last couple of years.

I am going to leave you with a few related links.

ASP.NET Core 1.1.1 Release Notes
Announcing New ASP.NET Core and Web Dev Feature in VS 2017
Project File Tools – Extension for IntelliSense in csproj
Razor Language Services – Extension for tag helper Intellisense

Migration from ASP.NET Core 1.0.x to 1.1

UPDATE: For a guide dealing with the conversion to csproj/Visual Studio 2017 check out this post.

On November 16th .NET Core 1.1 was released including ASP.NET Core 1.1 and Entity Framework 1.1. Each of the links contain the details of what was including in the 1.1 release. Unlike some of the previous migrations this is pretty simple.

I will be using my normal ASP.NET Basics solution for this upgrade. The examples will be out of the Contacts project. This post is coming out of order so the repo that goes with this post will contain some items not covered in posts yet. The starting point of the repo can be found here.

Installation

Make sure you already have Visual Studio 2015 Update 3 installed with .NET Core 1.0.1 tools Preview 2 installed. If not use the previous links to install the needed versions. Next head over to the download page for .NET Core and under All downloads and select Current and SDK and select the download for your OS.

downloaddotnet

Another option is to install Visual Studio 2017 RC which can be found here.

Project.json

Project.json is the file that contains all the versions of assembles used by the application. A couple of items need to edited by hand and the rest can be updated using NuGet UI or you can change them all by hand if you like.

First the by hand items. The platform version needs to be updated to 1.1.

The second by hand item is the net core app version in the frameworks section.

Here is the resulting dependencies and tools sections.

Make note that using the NuGet UI will update the dependencies but not the tools section. For some reason the tools section doesn’t seem to have intellisense so I ended up searching the NuGet site to find the new versions. If you do end up changing the tooling version I recommend doing a  dotnet restore in the project directory from the command prompt to ensure the proper versions get downloaded.

Wrapping up

As I said this was a really pain less migration. Make sure you check out the release pages ( .NET Core 1.1ASP.NET Core 1.1 and Entity Framework 1.1) for the details on what has changed. For example ASP.NET Core has gotten significant performance increases with this release as well as URL Rewriting Middleware and Response Caching Middleware.

It has been less than six months since the initial release of ASP.NET Core until the 1.1 release which a huge increase in the pace of releases compared regular ASP.NET. From what I have see this is a pace the team will continue. Check out the roadmap for a preview of things coming in 1.2.

The code in its final state can be found here.

ASP.NET Core Basics: API Controller

This week’s post is going to cover the creation of an API controller. The starting point for this post is based on this post from last week and the starting state of the code can be found here.

Scaffolding

Using the same  Contact model class from last week’s post Entity Framework Core’s scaffolding can be used to generate an API controller for us with all the read and write actions already written. To begin in the Solution Explorer window right click on the Controllers folder and select Add > New Scaffolded Item.

AddNewScaffoldedItemMenu

On the Add Scaffold dialog select API Controller with actions, using Entity Framework. This option will create an API controller with read and write actions based on a model.

AddScaffoldApi

On the Add Controller dialog for the model class select the  Contact class, for the data context class select the existing  ContactsContext. Finally enter the controller name you would like to use. I am using ContactsApiController since the MVC controller from last week’s post is already named ContactsController.

AddApiControllerDialog

Click add and the scaffolding process will create a ContactsApiController in the Controllers folder. With that the project now contains a fully functional contacts API that will handle gets, puts, posts and deletes with zero code changes.

Test with Postman

Postman is a great tool that I always use when developing an API that allows me to exercise all the functions of the API before any clients have been built. I know you can do some of the same things using a browser, but Postman was built for this type of usage and it shows. Postman is free and you can grab it from here as a Chrome app or they have app versions available here.

After installing the application and running it you will see something like the following.

PostmanBlank

It is best to have some data available for testing so in the case of this application I recommend using the UI added in last weeks post to add a couple of contacts.

Now that some data is available it is time to test the  GetContact function on the  ContactsApiController. If you run the application it should open in a browser from which you can copy the URL, or right click on the project select properties then on the Debug tab copy the URL from the App URL field.

ProjectProperties

Paste the base URL in the URL box in Postman and then add on the route for the endpoint you are wanting to test. In this case I want to test the the  GetContact function on the  ContactsApiController so I will be using the a URL of  http://localhost:13322/api/contactsapi. Next make sure contact application is running and then click the send button in Postman. The application should respond and the results of the API call will be displayed on the body tab of Postman.

PostmanGetContacts

Postman can be used to try out pretty much all aspects of the API that an application has. For example if you wanted to test out the  PostContact then in Postman click the down arrow next to Get and select Post. Next select the upper body tab (in the request area) and the click the raw radio button. Then to the right of the radio buttons hit the down arrow and select JSON (application/json) and then it the large text box you can enter the JSON that will be sent to the server when you click the send button. The following is an example of a post request.

PostmanPostContact

Wrapping Up

This application now has a fully functional API and we have covered how test it using Postman.

The next step would be to create some sort of client to actually utilized the API such as an Aurelia or Angular 2 application.

The code for this post can be found here.

ASP.NET Core Basics: MVC Controller with Entity Framework Core

Last week’s post covered the installation and creation of a new project in ASP.NET Core. This week I will be expanding that existing project to create a basic contact list which will use Entity Framework Core and its scaffolding capabilities to generate the needed files from a model class. This code from last week is being used as a starting point for this post.

Add a Model

To start off I need a class to represent the information for a single contact. In the default setup the proper place to store this type of class is in the Models folder. To add a new class from the Solution Explorer window right click on the Models folder and select Add > Class menu option.

AddClassMenu

This menu choice will bring up the Add New Item dialog defaulted to adding a new class. Enter the name as Contact.cs and click Add.

AddNewItemDialogContact

The following is my resulting  Contact after adding the properties of a contact that this application is going to use.

Scaffolding

Now that the application knows what a  Contact looks like we can take advantage of a feature of Entity Framework Core called scaffolding. Scaffolding can be sued to create a number of different setups based on a model, but in this case it I am using it to generate a MVC Controller with views, using Entity Framework which will result in a controller, DbContext and associated MVC razor views being created.

In the Solution Explorer window right click on the Controllers folder and select Add > New Scaffolded Item.

AddNewScaffoldedItemMenu

On the Add Scaffold dialog select MVC Controller with views, using Entity Framework. This is the only option that will create views. Now click the Add button.

AddScaffoldDialog

The Add Controller dialog will be shown next. First select the model that should be the base of the scaffolding operation which is the  Contact class for this project. For the data context class option I used the plus (+) button to add a new one since this project doesn’t have an existing data context that I want to use.

AddControllerDialog

After clicking add and letting the process finish the Controllers folder will now contain a  ContactsController and in the Models folder there will be  ContactsContext. I always move the newly created context out of the Models folder and into the Data folder to match the location used for the ApplicationDbContext.

Entity Framework Migration

Now that the application has a contact model and DbContext it is time to create an entity framework migration which is the mechanism entity framework uses to create and/or migrate a database to match the changes made in the models of an application. Migrations can be added within Visual Studio via the Package Manager Console or from a command prompt using the .NET CLI. I am going to walk through both, but keep in mind you only need to use one.

Package Manager Console

To open the Package Manager Console use the View > Other Windows > Package Manager Console menu. Which show a window that looks like the following.

PackageManagerConsole

To add a migration use run the  Add-Migration Init-Contacts -Context ContactsContext command. The Package Manager Console is using powershell so  Add-Migration is a command that take a parameter that is the name of the migration which is  Init-Contacts in this case.  -Context ContactsContext is required in this application because it contains more than one DbContext and the command has to know which DbContext it is working with.

.NET CLI

Open a command prompt and navigate to your project’s directory and then run the  dotnet ef migrations add Init-Contacts --context ContactsContext command. This is does exactly the same thing as the Package Manager Console above with just slightly different syntax.

Regardless of which version is used you will see a new Migrations folder added to the root of the project that contains a snapshot of the models referenced by the relevant DbContext as well as a migration file named by using a time stamp plus the migration name.

Automatic Database Migration

In the early stages of a project (or always if it meets your need) it is nice to automatically apply migrations instead of having to do so manually using the package manager console or the .NET CLI. One way to accomplish this is to add a static flag to the constructor of the DbContext in question and if that flag is false then use  Database.Migrate() to apply any migrations that the database is missing. Here is an example using my  ContatsContext class with the flag named  _created.

Add Navigation

At this point you could type in a URL that would take you to the index action of the new  ContactsController, but it would be much more useful to add a link to the sites navigation bar to provide an easy way to access the new functionality. The code for the navigation bar can be found in  _Layout.cshtml which is located in the Views > Shared folder.

The navigation bar is defined using an unordered list with a class of “nav navbar-nav”. Add a new link to the unorderd list labeled Contact List. This new link needs to point to the index action of ContactsController. ASP.NET Core provides some tag helpers to assist in building links to controller actions. Using the  asp-controller and specify “Contacts” as the controller which will resolve to the  ContactsController and then use  asp-action set to “Index” to point to the index action.

Wrapping Up

Now when the application is run there will be a link for Contact List at the top that will trigger actions in the new controller and backing database table.

Next week I play to take this same project and add a web API end point to it and show how that end point can be verified using Postman.

The code that goes with the post can be found here.

ASP.NET Core Basics: Project Creation

With ASP.NET Core released it seems like a good time to do a series of posts on the basics of this new platform starting with getting a new project up and running.  In this post I am going to walk through installation of ASP.NET Core and then move to project creation. This project will end up being a basic contact list application although there will not be much specific to that end goal in this post.

Installation

All the software needed for this post can be found at http://dot.net. I will be using Visual Studio 2015 in my examples and if you don’t have it installed already it can be downloaded using the Download Visual Studio 2015 button on the right of the above page or by clicking here. If you already have Visual Studio 2015 installed please ensure you have installed Update 3.

The next bit of software you will need is found by clicking the Download .NET Core 1.0 or clicking here. This page has a good write up getting started with .NET Core, but all you need is the install for .NET Core 1.0 for Visual Studio which can be found here.

To verify that .NET Core is installed open a command prompt and run  dotnet --version which will print the current version of .NET Core you have installed. As of this writing this my version is 1.0.0-preview2-003121. While .NET Core its self has been officially released the tooling is still in preview which is why the version contains preview2-003121.

Project Creation

Launch Visual Studio and from the File > New menu select Project…

NewProject

This will load the New Project dialog. On the left side under Templates > Visual C# > .NET Core select ASP.NET Core Web Application (.Net Core) or you can use the search box in the upper right of the screen to search for “ASP.NET Core Web Application (.Net Core)”.

NewProjectDialogContacts

Next on the New ASP.NET Core Web Application dialog select Web Application. This option creates an application with example MVC Views (razor) and an example controller. Notice the note that this template can be used for RESTful HTTP services as well. Next click the Change Authentication button.

NewAspNetCoreWebApplication

For this example I am going to use Individual User Accounts. This option adds UI, models, controllers, etc. to allow registration and management of user accounts. Since the option needs a database to store account information it include Entity Framework Core. Click OK on the Change Authentication dialog and then click ON new web application dialog.

ChangeAuthentication

Project Overview

After the creation process is finished got to the Solution Explorer window and you will see a set up similar to the following.

SolutionExplorer

I am going to point out a few of the files and folder that are part of a newly created application. Fist is  wwwroot which is where static files will be severed as long you are using the static files middleware.  This is where images, CSS and JavaScript should go.

appsettings.json is where you will find connection strings and logging settings by default. Your own settings can be added here as well.

project.json is where you will find all your project’s dependencies (using the NuGet UI or Package Manager console both write to this file), tools, frameworks, build options, runtime options, publish options and scripts are all defined. Thankfully this file has good support for intellisense if you decide to edit it manually. This file covers a lot, but for this introduction I am going to avoid digging into the specifics.

Startup.cs is the last file I want to call out. Its generated contents are fine for this example project, but it has a couple of functions you should be aware of. First ASP.NET Core comes with dependency injection built in and the  ConfigureServices function is where items are registered with the built in container. The second function is  Configure and this is the function where the HTTP request pipeline for your application is configured using various middleware.

Wrapping Up

At this point you have a web application that can be run (press F5 to run with the debugger attached or Ctrl + F5 to run without the debugger). With no code changes you now have a web application that has basic navigation, controllers, views and authentication.

With this series of post things are being kept intentionally short and focused on one or two main topics. Next week will build on this basic project by adding in the ability to manage contacts, using a new controller and associated razor view which will be persisted to a database using Entity Framework Core.

The code that goes with this post can be found in this GitHub repository.