meeple142/dihouseexample

Notes: make two Solutions, DI and no DI. it was confusing Should it follow clean arch? that could be too much cog load Steps: Show ERD/UML for DomainNoDI, point out the direction of dependencies/arrows Have them new-up a House can call start and end day. Show how its easy to "new up" a House with this bad way New Problem: new is glue Mention we can't change this code at runtime. Two biggest use cases 1. Runtime, pick implementation 2. Testing "You might say ok then we need to pass in the instance." Show how we can change to pass in the instance instead (no interface) New Problem: What if I want to change how one of these methods work, use interface (or abstract class). Show how to extract interface from class with vs 2022, update class and dependant class to use interface Show updated UML, point out the reverse arrows Add new implementation of class that has a different calculation for the return value and show with an if statement we can new-up the one we want and pass it in Show updated UML with the two implementations. "Where this technique is used the most is in unit testing" Show how by trying to test House by trying to switch out one of the dependencies
need to change at least one of the classes' methods to return a calculated value so it makes sense to want to swap out to a hardcoded value with a Unit test implement the class again but hardcode the response for testing "this way we remove all confounding variables and only test the code we really want to test. That way if there is an error we know exactly where the problem is. There is a time for integration testing too, but this is unit testing" This is called IOC, inversion of control, or Dependance Inversion or Dependency Injection "Great, I'm convinced lets DI all the classes" Switch to the new DI project and show the new UML Then have them new up a House New Problem: I don't want to write all this code every time! point out that now we have the flexibility to change the code every time and that's cool but still a lot to write. Fix: IOC container for the win! Demo: show how to add House class as class to the container as transient. then build the container then ask the container for a House, show requiredService vs getService Then call startDay and endDay on house. Run show the error the container doesn't know how to make the other interfaces Explain that it's only run time check add all the other interfaces and classes to the container as transient Then run again. Ya! it works Show you can get a different instance just by asking for one Demo: show how you can add an if statement to decide what to implementation to add to the container. Demo: other things you might want to do with a container shows what happens if more than one class that implements an interface is added show how to get them all in a list Show singleton, and scoped show how to get a scope and demo getting the same instance in the same scope Show making an instance and then added that to the container as singleton go back to basic DI code and say ok now that you have the basics it's still mostly the same amount of code the magic comes when using this to cross layers in Clean Architecture Switch to a basic clean architecture project set up, Have them build this in another demo or now? switch the main from newing-up all the things to making a IOC container and getting an instance and running the code Then say thats cool but presentation has to know how all the layers work, not good Make an extension method that attaches to the IOC Container class in application and infrastructure. and farm out the pieces to the right parts call them from main before you build then run and show works Then show to make a new class in application it can pull in the infrastructure services really easy by just asking for them in the constructor This is the magic!

Teach Configuration in a simular bare bones way, by newing up the class yourself
    teach the settings object with interfaces too
    IOptions



Then can introduce IHostBuilder
    It does DI, Configuration, Logging and process management for you! "For CLI we don't really need the process management
    
    set that up showing that it's the same just a little different
    take the time to teach logging now using ILogger<class>
        Other logging things 
            scopes?
    can log to file and console - maybe save till serilog
    change some Application classes to use ILogger
    Show how Ilogger is better for multi Thredding
    flush on shutdown Ilogger

Cool now our CLI can only do one thing
    Build "Actions" that template uses
    "What if we want more verbs and params"
        lib

Show the extra things that the template has
    adding Key Vault
    adding current user service
    adding the database
    the SOA properties on the Options Object
    Serilog

Now we can teach mediatr
    highlighting the pipeline and vertical slices, functional nature
    Then set up verbs to take mediatr and make requests
        Set up each pipeline behavior
            logging
            validating
            error handling
            Other?


Then can teach ASP.Net (or maybe blazer?) "as just another presentation" 
    Teach the basic parts that ASP.Net needs with a picture
    Then show where in the template those things are