clients and profits x cannot find the database anymore

Clients and profits x cannot find the database anymore series#

Finally, the commands to write to the database.A class which inherits EF Core’s DbContext class, which contains the setup/configuration of EF Core.A class, or classes, to map to your database – I refer to these as entity classes.A database server, such as SQL Server, Sqlite, PostgreSQL….

A look at what you need to access this database via EF Coreįor EF Core to write to the database I have shown you need 5 parts I’m not going to show the classes because of space, but you can see these classes here in my GitHub repo. Book, BookAuthor, Author, with properties with the same name as the columns shown in the tables. Theses tables are mapped to classes with similar names, e.g. and b) it had each of the basic relationships that can exist between tables. I chose this because a) its easy to understand because of Amazon etc. My Book App as I call it starts out in chapter 2 with the following five tables shown in the figure below. The classes/tables I’m going to work with In this introduction I am going to describe the database structure and then give you a simple example of writing to that database. TIP: If you already know EF Core then you can skip this section – it’s just an example of how you write to a database.įor the examples in my book I have created a small web application that sells books – think super-simple Amazon. Setting the scene – the basics of EF Core writing to the database If the deleted class has relationships then the database can sort out what to do, but you can change the delete rules.

EF Core’s Remove method will delete the row in the database pointed to by the primary key value in the class you provide as a parameter.

When you call SaveChanges it compares each clear read in with its original value and only creates commands to change the specific class/property that was changed. It does this by holding a hidden copy of the class(es) read in.

EF Core can detect when you change a property in a class you read in from the database.

It also fills in any foreign key, either with the actual key of an existing row, or a pseudo-key for links to new classes.

For each linked class it works out if it needs to create a new row in the database, or jus link to an existing row in the database. EF Core finds all the links from the added class to other classes.When you call the EF Core command Add to create a new entry many things happen.This makes it easy for the developer to write out classes with complex links between them. To do this it has to set the right order to write out the classes so that it can get set the any linked class. EF Core can create a new entry in the database with new or existing relationships.There are unit tests that go with the content in this article – look for unit test class whose name start with “Ch06_”. NOTE: There is a companion GitHub repo at. I am also added a LOT of new content from my experiences of working with EF Core on client applications over the last 2½ years.

Clients and profits x cannot find the database anymore series#

This “EF Core In depth” series is inspired by what I found while updating my book “ Entity Framework Core in Action” to cover EF Core 5.

Handling Entity Framework Core migrations: applying a migration – Part 2.

Handling Entity Framework Core migrations: creating a migration – Part 1.

EF Core In depth – Tips and techniques for configuring EF Core.

EF Core In depth – Soft deleting data with Global Query Filter.

EF Core In depth – what happens when EF Core writes to the database? (this article).

EF Core In depth – what happens when EF Core reads from the database?.

Here is the current list of articles in this series: This article is part of a “EF Core In depth” series. But this is a “deep dive” so be ready for lots of technical detail, hopefully described in a way you can understand. I do assume you know EF Core, but I start with a look at using EF Core to make sure we have the basics covered before I dive into the depths of EF Core. This is CUD part of the four CRUD (Create, Read, Update, and Delete) accesses. The first was about reading from the database, and this article is about writing to the database. This article is the second “under the hood” view of what happens when you use EF Core.