I've just started using EF in VS2010. That thing is just amazin'.
I frankly can't understand something. For example I have EntityType with property, they generated from database structure.
Now, I have to simply override that property in my code. I don't need to save value of the property back into DB, but everytime when it gets read from DB it should be substituted with run-time calculated value.
Of course I can create derived class based on my EntityType but I've tried and found kinda difficulties, I'm not sure this is kinda right way to do. Anyway even when I try to change the whole EntityType to Abstract, damn Visual Studio doesn't want to validate that and says something like:
"Error 2078: The EntityType 'AssetsModel.Asset' is Abstract and can be mapped only using IsTypeOf."
"Error 2063: At least one property must be mapped in the set mapping for 'Assets'"
What the hell is this suppose to mean I dunno..
Any ideas?
The best approach would be to use Partial Classes and then create a new ReadOnly property to calculate the value in the getter.
Related
I want to set the "standard" TYPO3 field "fe_group" in the extbase controller. As far I see there no "standard" getters and setters? https://typo3.org/api/typo3cms/class_t_y_p_o3_1_1_c_m_s_1_1_extbase_1_1_domain_object_1_1_abstract_entity.html
I tried to implement them in the model, but it does not work - I do not get any error but it is never set.
What exactly I want to do:
I have an object of type \TYPO3\CMS\Extbase\Domain\Model\FrontendUserGroup and I have an object of my record type (I can set other fields without any problems).
Now I want to do something like:
$myobject->addFe_group($feusergroup);
Do I have to implement this by my own to my model? I tried to implement fe_group as ObjectStorage and also as string - does not work? :-(
Does anyone have a solution for this?
Thank you
Christian
First of all: In models please name functions and properties lowerCamelCase. So a field "fe_group" in TCA would become "feGroup" in the model and the function would be "addFeGroup".
FrontendUserGroup model has a function addSubgroup to add other groups as subobjects. Is this the right thing for your purpose or what you need those relation to another group for?
https://typo3.org/api/typo3cms/class_t_y_p_o3_1_1_c_m_s_1_1_extbase_1_1_domain_1_1_model_1_1_frontend_user_group.html
I've decided to use fluent mapping in Entity Framework. My intention was to map everyting by code without any atributes and auto mapping functions. Best way I've found is class EntityTypeConfiguration, that I implement for each entity in my project.
Later I add property to one of my entity. This property isn't needed to be persisted. I've expected, that until I add mapping for this property, it will be ignored by database and persistence layer. Unfortunatly it doesn't work that way, and property is mapped. Only way is to use Ignore method or NotMapped attribute, but I don't want to do it explicitly.
Is there any way, to stop Entity Framework from automapping? I've tried to remove all Conventions from DbModelBuilder, but it doesn't help.
So far as I am aware, there is no other way around it. You need to use either Ignore() or [NotMapped]. I tend to prefer the former as it does not clutter up the model.
Actually I have tried a lot of ways:
- custom convention to remove mapped properties
- removing all conventions
But the easiest (and cleanest) way was to use reflection inside the mapping class and to disable all property mappings that weren't configured.
The code for that (and also an usage example) is inside my public gist.
https://gist.github.com/hidegh/36d92380c720804dee043fde8a863ecb
In Entity Framework 5 model first, there seem to be some breaking changes due to the way the class files are generated (No more code generation, but T4 templates)
2 examples:
The generated context file doesn't implement IDisposable anymore
There isn't a constructor which takes a connectionstring anymore
Are there more breaking changes? And what is the solution to them?
The default code generated from a model in Entity Framework 5 now inherits DbContext instead of ObjectContext.
This still implements IDisposable, but if you're getting an error from a line of code similar to this:
using (var mymodel = new MyModelContext()) { ... }
...complaining about not implementing IDisposable, then your problem is most likely that your model is defined in a separate assembly that references EF5 and you have not added an EF5 reference to your project.
As Ladislav Mrnka has already mentioned in his answer, if you want to pass a connection string to the constructor you have to create your own constructor manually to do this.
If you want to switch Entity Framework back to the older style of generated code, which will automatically generate the constructor you're looking for, then follow these steps:
Click on the designer surface of your EDMX file, and look at the properties window. Find a property called "Code Generation Strategy" and set this to "Default" instead of "None". This will tell Visual Studio to start creating the code for your object model in MyModel.Designer.cs in one big file, this time using ObjectContext instead of DbContext.
Delete the following sub files from below your EDMX file: MyModel.Context.tt, MyModel.tt. These are the auto generated files that you don't want anymore. If you don't delete them you'll get class naming conflicts because your objects will be created twice.
The generated context file doesn't implement IDisposable anymore
IDisposable is still implemented by the parent context type. The generated type is still disposable.
There isn't a constructor which takes a connectionstring anymore
It now uses convention to get connection string but you can add your own constructor either to template or to your partial class part of the context.
Are there more breaking changes? And what is the solution to them?
It is whole breaking change because it uses different API - DbContext API instead of ObjectContext API which means different types, different methods, POCO entities etc. If you want to get back to original code generation you have to delete those T4 templates and enable code generation as described in .Designer.cs file but the current recommended way is to use POCOs and DbContext API.
I was having the same issue with the using statement needing a type that extended IDisposable... Turns out that I forgot to reference System.Data.Entity in my project... Added the reference and it fixed the problem.
Just clean and build the project, don't forget to add the reference to your entity.
I have a subclass in a different assembly to its base class. The parent is a POCO class used for EF Code First.
When I try to add an instance of inherited class to the database I get InvalidOperationException: "Object mapping could not be found for Type with identity 'Foo.Bar.MyInheritedClass'".
It works fine if subclass is in same assembly as base class.
In regular EF the solution seems to be a call to ObjectContext.MetadataWorkspace.LoadFromAssembly(assembly). But I can't figure out how this relates to Code First.
Any advice?
I'm using Entity Framework 4.1 RC.
I solved this by inheriting from the first assembliy's DbContext, adding a DbSet<> for the derived class, and then adding new instances of derived type to to that.
Posted code on MSDN forum here.
I know this post is a bit old, but I was able to accomplish this using #Dave's recomendation inside the constructor:
public Context() {
((IObjectContextAdapter)this).ObjectContext.MetadataWorkspace.LoadFromAssembly(
System.Reflection.Assembly.GetAssembly(
typeof(--[Inherited DbContext]--)));
}
I'm quite new to EF (Entity Framework 4) and I got the same exception when I made changes in the model.
My problem turned out to be that I did not know EF need all the names on all the navigation properties to agree, not only their type. For example if there is a navigation property named foo, then there needs to be a declared variable in the corresponding class with the very same name.
I know that i can enter/add new properties via code manually into partial classes but i wanted to use the model to add my new properties - reason being is that i can control a number of different attributes like NULL and things like that... and of course the code generations works great..
I added some foreign keys manually just on the model and they work great.
But everytime i add a SCALER PROPERTY i get an error in vs 2010 which says
Error 2538 Error 11009: Property 'testprop' is not mapped.
I can't believe i must map a custom property that i created to a column in the db.... is there no way to say "IGNORE" this property or treat as an unmapped property??
This way my code generation will create the required items BUT i don't get the error
Any help on this would be really helpful.
As i say i know i can edit things manually but wanted to update the model rather than edit a partial class....
I am sure i am missing something obvious?
With EntityFramework 5 you can use the NotMappedAttribute for unmapped properties. So, you can migrate to EF5 or use partial classes on EF4.
I believe that EF will on allow you to use the Model Designer to map to something that exists. If you want to create a property that doesnt exist, you'll have to use the partial class.
I had the same error - you can use the NotMappedAttribute for unmapped properties...