This chapter is from the book
This chapter is from the book
This chapter is from the book
Updating The Model
Because the designer is so closely linked to the underlying EDMX, changes you make in the designer will update the EDMX. (And vice versa, of course.) The designer itself works as you would expect if you’ve worked with other designers in Visual Studio. We’ll look at some complex manipulations in later chapters, but here are the basics:
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Put On Your Thinking Hat
Can you figure out how to perform the following tasks in the designer?
How would you check the data type of an entity property?
You know that a relationship in a database can be one-to-one or one-to-many. The “one” or “many” is the relationships MULTIPLICITY. The multiplicity of an association in an EDM can also be many-to-many. How can you determine the multiplicity of an association in the designer?
An ENTITY KEY in an EDM is like the primary key of a table. Like a primary key, it must be unique, and like a primary key, it can be composed of multiple entity properties. How can you find out if a given entity member participates in the entity key?
In the Entity Framework, the model itself has properties. How do you display the properties of the model in the designer?
Put On Your Thinking Hat
How’d you do?
How would you check the data type of an entity property?
- This is an easy one: Just select the property on the designer surface and its type will be displayed in the Properties window.
- But there’s another way that I haven’t shown you: Right-click on the design surface and choose Scalar Property Format. Did you find that one? Try it now.
You know that a relationship in a database can be one-to-one or one-to-many. The “one” or “many” is the relationships MULTIPLICITY. The multiplicity of an association in an EDM can also be many-to-many. How can you determine the multiplicity of an association in the designer?
- It’s shown in the Properties window if you select the association, and also directly on the diagram.
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An ENTITY KEY in an EDM is like the primary key of a table. Like a primary key, it must be unique, and like a primary key, it can be composed of multiple entity properties. How can you find out if a given entity member participates in the entity key?
- It’s shown in the Properties window when you select the property, but notice that it doesn’t tell you if this is the only property that participates in the key, so you might have to check several properties to be sure. We’ll see another way to check the Entity Key when we look at the Model Browser later in this chapter.
In the Entity Framework, the model itself has properties. A model is called an EntityContainer in the EDMX and a ConceptualEntityModel in the designer. How do you display the properties of the model in the designer?
To show the properties of the model itself, just click on a blank area of the designer surface.
Take a Break
Why don’t you take a break before completing the review and we move on to updating the model?
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