Contents
You can configure data models using Data Annotations or Fluent API. Data Annotations gives the only subset of configurations, Fluent API provides full set of configuration options available for code first. In this blogpost explains how to configure entities using Fluent API of Entity Framework Core or EF6 above versions for the Code First approach. This will give you details about how to configure business rules with Fluent API methods for PrimaryKey, Unique, Index, Required, Identity, etc. Provide transactional guarantees for creating, updating or deleting data across multiple tables in a single Prisma Client query. If any part of the query fails , Prisma Client rolls back all changes.
Entity Framework Fluent API is used to configure domain classes to override conventions. EF Fluent API is based on a Fluent API design pattern (a.k.a Fluent Interface) where the result is formulated by method chaining. Fluent API is used to configure data models to override conventions.
Default Schema
If your database column name needs to be different than the property name of the Data Model you can use the HasColumnName to configure column name. Fluent API Ignore method can be use to configure Not mapped columns. The following column configures DiscountAmount column as not to be mapped. Prisma Client provides the some, every, and none options to filter records by the properties of related records on the “-to-many” side of the relation. I haven’t seen a lot of fluent interfaces out there yet, so I conclude that we don’t know much about their strengths and weaknesses.
Yet, the truly fascinating feature of fluent APIs in static languages is their ability to enforce API protocols at compile-time. An application programming interface makes it possible to access an application from within code. In this context, an application can be a single class, a software library or module, an external tool or service , or even a physical artifact .
A typical example of the use of this class is something like the following. Table will be created on the database which is shown in the below image. As you can see on the example above, it’s necessary to set the foreign key, using the “HasforeinKey”. EF Core does not support many-to-many relationships without using a third entity to represent the join table. So for this case, we need to have another entity, which will be the ActorMovie.
Map Entity to Table
When the database is generated you see the following tables in your database as shown in the following image. Excludes a property from the model so that it will not be mapped to the database. In this chapter, we will continue with the simple example which contains Student, Course and Enrollment classes and one context class with MyContext name as shown in the following code. In typed languages, using a constructor requiring all parameters will fail at compilation time while the fluent approach will only be able to generate runtime errors, missing all the type-safety checks of modern compilers.
- In Swift 3.0+ returning self in the functions is one way to implement the fluent pattern.
- Its members are programming language developers, educators, implementers, researchers, theoreticians, and users.
- However at database level Products and Product inventory details needs to be in separate tables.
- The fluent API lets you fluently traverse the relations of your models via function calls.
- They were using this library called Fluent Assertions to write their assertions, and although it doesn’t fundamentally change the test or performance, the code looks readable.
- Fluent interface can also be used to chain a set of method, which operates/shares the same object.
It is the main class and on which you can configure all your domain classes. This code centric approach to building an Entity Data Model is known as Code First. Note that a “fluent interface” means more than just method cascading via chaining; it entails designing an interface that reads like a DSL, using other techniques like “nested functions and object scoping”.
Explains how to configure entities using Fluent API of Entity Framework Core or EF6 above versions for the Code First approach. Now in the Dbcontext class, it’s necessary to override the method OnModelCreating. Inside this method, we are going to set the configuration for the entities using Fluent API. If you want to know more about how can you create the structure of your project, you can check the article “Creating an Application from Scratch using .NET Core and Angular — Part 1” clicking here.
The primary key table contains only one record that relates to none, one, or many records in the related table. In a one-to-one relationship, the primary key acts additionally as a foreign key and there is no separate foreign key column for either table. In Entity Framework, by default Code First will create a column for a property with the same name, order, and datatype.
One way around this may be to use builder objects that are only used in this context. You should choose your return type based on what you need to continue fluent action. JMock makes a big point of moving its types depending on what’s likely to be needed next. One of the nice benefits of this style is that method completion helps tell you what to type next – rather like a wizard in the IDE. In general I find dynamic languages work better for DSLs since they tend to have a less cluttered syntax. Using method completion, however, is a plus for static languages.
In this case, to configure one-to-many relationship using Top Cloud Security Companies Reviews 2022, you need to use HasForeignKey method as shown in the following code. For example, in the above diagram Student and Enrollment tables have one-tomany relationship, each student may have many enrollments, but each enrollment belongs to only one student. In most cases, the Entity Framework can infer which type is the dependent and which is the principal in a relationship. However, when both ends of the relationship are required or both sides are optional the Entity Framework cannot identify the dependent and the principal. When both ends of the relationship are required, you can use HasRequired as shown in the following code. This type of relationship is not common because most information related in this way would all be in one table.
Registers a type as a complex type in the model and returns an object that can be used to configure the complex type. This method can be called multiple times for the same type to perform multiple lines of configuration. Migration is a way Three Different Types of Enterprise Systems Chron com to update the database in an incrementally way. So always when you create a new entity class in the application, or when you change some existing entity, you need to generate a new migration and update the database with this migration.
Delete all related records
Following are the Student and Course classes in which Student and Course has many-tomany relationship, because both classes have navigation properties Students and Courses that are collections. The foreign key is defined on the table that represents the many end of the relationship. A one-to-one relationship is created if both of the related columns are primary keys or have unique constraints. Entity mapping is just some simple mappings that will impact Entity Framework’s understanding of how the classes are mapped to the databases.
In the below table we have listed down some of the most common methods of Entity Framework Core Fluent API. We are going to see how we can create relationships between classes using EF Core and Fluent API. For demonstration purpose, I’ve created a Console Application using .NET Core 3.1. Prisma Client provides the is and isNot options to filter records by the properties of related records on the “-to-one” side of the relation.
As you can see in the above code that Key and ForeignKey attributes are used for ID property in StudentLogIn class, in order to mark it as Primary Key as well as Foreign Key. In the following example, the Course Title property should be no longer than 24 characters. When the user specifies value longer than 24 characters, then the user will get a DbEntityValidationException exception.
Nested reads
It is a trendy practice for making elegant and concise interfaces. In this post we learned how to implement basic fluent APIs, showed that they can enforce API contracts at compile-time, and saw that they can even be used to embed domain-specific languages. Like with StringBuilder, and builders in general, having the fluent methods return the current object is the simplest way to go.
Update a specific related record
Instead of creating a normal class, I thought of writing it as a “Fluent” class. I’ll walk through a toy problem, and show you two ways to create a Fluent API, a simple way and a more better way to create a Fluent API. To enforce a protocol with a fluent API, we first formalize it in a finite state machine diagram. Configurations are added to the ModelBuilder using an ApplyConfiguration method instead of being added to a Configurations collection. For example, the Student table and the Course table have many-to-many relationship. Some of them are available in the data annotations and you can apply some even more complicated ones with a Fluent API.
When the database is generated you will see that relationship is created as shown in the following image. To configure one-to-zero or one relationship between Student and StudentLogIn using Fluent API, you need to override OnModelCreating method as shown in the following code. Let’s take a look at the following example where we will add another class into our model to create a one-to-one relationship.
In a How hard is JavaScript to learn after wetting my feet in Python, we can link together different functionality to get a particular result. The ACM Special Interest Group on Programming Languages explores programming language concepts and tools, focusing on design, implementation, practice, and theory. Its members are programming language developers, educators, implementers, researchers, theoreticians, and users. When the database is generated you will see that the relationship is created as shown in the following image.