Entity Framework 6.2 Download

Prior to .NET 3.5, we (developers) often used to write ADO.NET code or Enterprise Data Access Block to save or retrieve application data from the underlying database.We used to open a connection to the database, create a DataSet to fetch or submit the data to the database, convert data from the DataSet to .NET objects or vice-versa to apply business rules. This was a cumbersome and error prone process. Microsoft has provided a framework called "Entity Framework" to automate all these database related activities for your application.

Entity Framework is an open-source ORM framework for .NET applications supported by Microsoft.It enables developers to work with data using objects of domain specific classes without focusing on the underlying database tables and columns where this data is stored. With the Entity Framework, developers can work at a higher level of abstraction when they deal with data, and can create and maintain data-oriented applications with less code compared with traditional applications.

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With EF Core, data access is performed using a model. A model is made up of entity classes and a context object that represents a session with the database. The context object allows querying and saving data. For more information, see Creating a Model.

Entity Framework 6.4 was the latest release of the classic framework. Although Entity Framework 6 is still supported, it is no longer being developed and will only receive fixes for security issues.[3]

A new framework known as Entity Framework Core (EF Core) was introduced in 2016 with similar but not complete feature parity.[4] Version numbering of this framework restarted from 1.0 and the latest version of EF Core is 8.0.[5]

Entity Types form the class of objects entities conform to, with the Entities being instances of the entity types. Entities represent individual objects that form a part of the problem being solved by the application and are indexed by a key. For example, converting the physical schema described above, we will have two entity types:

The logical schema and its mapping with the physical schema is represented as an Entity Data Model (EDM), specified as an XML file. ADO.NET Entity Framework uses the EDM to actually perform the mapping letting the application work with the entities, while internally abstracting the use of ADO.NET constructs like DataSet and RecordSet. ADO.NET Entity Framework performs the joins necessary to have entity reference information from multiple tables, or when a relationship is traversed. When an entity is updated, it traces back which table the information came from and issues SQL update statements to update the tables in which some data has been updated. ADO.NET Entity Framework uses eSQL, a derivative of SQL, to perform queries, set-theoretic operations, and updates on entities and their relationships. Queries in eSQL, if required, are then translated to the native SQL flavor of the underlying database.[citation needed]

Entity types and entity sets just form the logical EDM schema, and can be exposed as anything. ADO.NET Entity Framework includes Object Service that presents these entities as Objects with the elements and relationships exposed as properties. Thus Entity objects are just front-end to the instances of the EDM entity types, which lets Object Oriented languages access and use them. Similarly, other front-ends can be created, which expose the entities via web services (e.g., WCF Data Services) or XML that is used when entities are serialized for persistence storage or over-the-wire transfer.[32]

Entities** are instances of EntityTypes; they represent the individual instances of the objects (such as customer, orders) to which the information pertains. The identity of an entity is defined by the entity type it is an instance of; in that sense an entity type defines the class an entity belongs to and also defines what properties an entity will have. Properties describe some aspect of the entity by giving it a name and a type. The properties of an entity type in ADO.NET Entity Framework are fully typed, and are fully compatible with the type system used in a DBMS system, as well as the Common Type System of the .NET Framework. A property can be SimpleType, or ComplexType, and can be multi-valued as well. All EntityTypes belong to some namespace, and have an EntityKey property that uniquely identifies each instance of the entity type. The different property types are distinguished as follows:[citation needed]

All entity instances are housed in EntityContainers, which are per-project containers for entities. Each project has one or more named EntityContainers, which can reference entities across multiple namespaces and entity types. Multiple instances of one entity type can be stored in collections called EntitySets. One entity type can have multiple EntitySets.[citation needed]

Any two entity types can be related, by either an Association relation or a Containment relation. For example, a shipment is billed to a customer is an association whereas an order contains order details is a containment relation. A containment relation can also be used to model inheritance between entities. The relation between two entity types is specified by a Relationship Type, instances of which, called Relationships, relate entity instances. In future releases, other kinds of relationship types such as Composition, or Identification, may be introduced.[citation needed]

Relationship types are characterized by their degree (arity) or the count of entity types they relate and their multiplicity. However, in the initial release of ADO.NET Entity Framework, relationships are limited to a binary (of degree two) bi-directional relationship. Multiplicity defines how many entity instances can be related together. Based on multiplicity, relationships can be either one-to-one, one-to-many, or many-to-many. Relationships between entities are named; the name is called a Role. It defines the purpose of the relationship.[citation needed]

A relationship type can also have an Operation or Action associated with it, which allows some action to be performed on an entity in the event of an action being performed on a related entity. A relationship can be specified to take an Action when some Operation is done on a related entity. For example, on deleting an entity that forms the part of a relation (the OnDelete operation) the actions that can be taken are:[36]

ADO.NET Entity Framework uses an XML based Data Definition Language called Schema Definition Language (SDL) to define the EDM Schema. The SDL defines the SimpleTypes similar to the CTS primitive types, including String, Int32, Double, Decimal, Guid, and DateTime, among others. An Enumeration, which defines a map of primitive values and names, is also considered a simple type. Enumerations are supported from framework version 5.0 onwards only. ComplexTypes are created from an aggregation of other types. A collection of properties of these types define an Entity Type. This definition can be written in EBNF grammar as:[citation needed]

Most development frameworks include libraries that enable access to data from relational databases via recordset-like data structures. The following code sample illustrates a typical scenario where data is retrieved from a database and stored in an ADO.NET DataTable so that it is accessible to the program's code:

As the company announced in May with Entity Framework 6.3 Preview, it has taken the traditional open source object-relational mapping (ORM) framework to the .NET Core space, joining Entity Framework Core as an option for leveraging the upcoming.NET Core 3.0.

As per the above figure, Entity Framework fits between the business entities (Domain Classes) and the database. It saves the data in the business properties entities and also retrieves the data from the database and converts it into the business entity's object automatically.

Entity Framework has a more granular mapping layer so that we can customize the mappings. For example, by mapping the single entity to the multiple database tables or multiple entities to the single table.

Modeling: Entity Framework (EF) creates an EDM (Entity Data Model), which is based on POCO (Plain Old CLR Object) entities with get/set properties of different data types. It uses this model when we have to query and to save the entity data to the underlying database.

Entity Framework Core supports various database management systems (see all). ABP framework and this document don't depend on any specific DBMS. If you are creating a reusable application module, avoid to depend on a specific DBMS package. However, in a final application you eventually will select a DBMS.

You can still use the data annotation attributes (like [Required]) on the properties of your entity while the ABP documentation generally follows the fluent mapping API approach. It is up to you.

ABP Framework has some base entity classes and conventions (see the entities document) and it provides some useful extension methods to configure the properties inherited from the base entity classes.

This will create a repository for each aggregate root entity (classes derived from AggregateRoot) by default. If you want to create repositories for other entities too, then set includeAllEntities to true:

This is especially important when you want to override a base repository method to customize it. For instance, you may want to override DeleteAsync method to delete a specific entity in a more efficient way:

That means, the methods return a single entity includes details by default while list returning methods don't include details by default. You can explicitly pass includeDetails to change the behavior. 006ab0faaa