Exibindo posts da categoria "Desenvolvimento sob medida"

Hierarchy with Entity Framework

MVC and MySql examples

The goal is to facilitate operations in hierarchical tables using functions available for hierarchyid data type.
There are two challenges:

  • Simplify use through set of simple commands.
  • Using Entity Framework without changes, enable hierarchy operations in other databases, in addition to SQL Server.

How?

We will use only five basic operations to maintain the hierarchy:

  • Adding a new element (as last child of a given parent).
  • Promotion. To the same level of his parent.
  • Demotion. Becomes the last child of the previous sibling.
  • Moving up approaching the parent.
  • Move down away from the parent.

Through these operations it is possible to position a record anywhere in the hierarchy.

1 min video »

Details

  • We will not use the hierarchyid field. In its place a varbinary field (892). This will allow the Entity Framework to map the field.
  • In hierarchy services functions we can convert the byte array data to SqlHierarchyid data type.
  • So the application can use the basic functions of the hierarchy handling.
  • This is even possible for other databases in addition to MS SQL Server.
  • Just use to the field that stores the hierarchyid data, a data type that is mapped to byte array.
  • For MySql, for example, varbinary worked in this application.

See the source code (+GitHub and +Nuget) !

Sample Projects on GitHub

  • HidMy – Accessing MySql using Hierarchy.Universal namespace.
  • HidMS – Accessing Sql Server using Hierarchy.SqlServer namespace.
  • Both project will load nuget package EntityFramework.Hierarchy.