What are the naming conventions you use for application domain model classes and presentation layer classes? Postfixes/Prefixes to distinguish the aim of the class from the first sight:
For example information about the person that is returned from DAL can be
public class PersonEntity
{
public Guid Id { get; set; }
public SexType Sex { get; set; }
public Date Birthdate { get; set; }
public string Name { get; set; }
public string Family { get; set; }
public string Patronymic { get; set; }
...
}
or may be you prefer PersonData or PersonInfo or something more appropriate?
Than I use databinding to create appropriate presentation. For example SexType should be converted to localized string (Male, Mann, Homme, Hombre, ...) Birthdate to appropriate date format (YYYY.MM.DD, DD.MM.YYYY, ...) and full name into -> Family N.P.
So I use another layer of classes for presentation databindings. Something like
public class PersonDecorator
{
public string Sex { get; set; }
public string Date { get; set; }
public string FullName { get; set; }
}
or may it's better to name such class PersonPresenter, or PersonView, or something more appropriate?
Thank you in advance!
The EntityPurpose convention for class names works just fine in a lot of places, especially if you have several entities (Persons, Cars, etc) and several layers (Model, View, Action, etc).
I'd name your class PersonPresentation.
Related
If you need to create one View from various entity (models), is it best to create a separate class as a ViewModel containing the specific properties that you need or is it better to create another entity with the specific properties and associate that entity with the rest of the entities in the ORM designer?
You can merge any number of models into one model by declaring them a property of the main m odel. Suppose that you have the following models:
public class Student
{
public int StudentID { get; set; }
public string StudentName { get; set; }
public int SchoolID { get; set; }
public virtual School StudentSchool { get; set; }
}
public class School
{
public School()
{
this.Students = new HashSet<Student>();
}
public int SchoolID { get; set; }
public string ASchoolName { get; set; }
public virtual ICollection<Student> Students { get; set; }
}
If you just set the Student class as your view model, you can retrive the School of your student and in this case you doesn't need to do anything.
However we suppose that you also need all schools and all students in your view as your view model. To do this, create another class and add the above classes as its properties:
public class MyModel
{
List<Student> MyStudents { get; set; }
List<School> MySchools { get; set; }
}
You can create any complex model you need by this approach...
I have a constructed a model using code first in C#. The model literally represents a container element for a website building application, in other words, the model defines a Div tag or some such HTML element. Like a Div tag which can contain multiple child elements, I have tried to represent this in my model, but the scaffolding to the DB, does not give me what I'd expect.
I should get a new many to many joins table, but instead I only get a single column in the DB which expects a single int data type.
Here is the model:
public class ElementContainer
{
public int ElementContainerID { get; set; }
public int PageId { get; set; }
public int? ParentElementContainerID { get; set; }
public string ElementContainerName { get; set; }
public ElementType ElementType { get; set; }
public string ElementClass { get; set; }
public PageAsset PageAsset { get; set; } // content of container
public List<ElementContainer> NestedContainers { get; set; }
}
The last line is the self-referential attribute which just appears as a column called ElementContainer_ElementContainerID
Thanks in advance!
I agree with Bahman, DB first is easier.
While I haven't tried to do what you are trying, your code looks like a self-Join that would do exactly what you describe.
This is a One-to-Many relationship. EF Navigation will pull a List of all nested children containers.
If you want to create a many-to-many relationship with EF Code-First, you should create another Entity
public class ContainerChildren
{
public int ElementContainerID { get; set; }
public List<ElementContainer> NestedContainers { get; set; }
}
this reference should help you to get the exact idea http://blogs.msdn.com/b/wriju/archive/2011/05/14/code-first-ef-4-1-building-many-to-many-relationship.aspx
I have a datamodel like
ModelA which contains a Collection.
ModelB contains a Collection as a backreference. That is failing because of cyclic references if I query with Include("ModelB"). Not good but I solved that via setting ModelB.List=null for each element.
The problem now is submitting a changed ModelA tree: I am adding ModelB-entities to ModelA.ModelB[]. Now the UpdateEntity function is complaining the it could not add elements of type ModelB which are declared static. The JSON deserializer is creating static arrays.
How is it possible with the combination of upshot/MVC4 to submit datamodels which are not completely flat? As it is not possible right now to create your own DTO objects where you might figure out something I am stuck now...
After investigating the error a bit better, I think the problem is the cyclic backreference:
The ModelA->ModelB->ModelA is breaking the storage of the data. "Could not add data of type ModelA to type ModelB".
As I mentioned the backreference was set to Null because the cyclic ref serialisation problem...
I hope the will be some easier way on doing more manually with DTO objects where I have mroe control.
Please see also: MVC 4, Upshot entities cyclic references for the beginning of the journey...
To solve the cyclic backreference, you can use the ignoreDataMember attribute:
public class Customer
{
[Key]
public int CustomerId { get; set; }
public string Name { get; set; }
public string Address { get; set; }
public double Latitude { get; set; }
public double Longitude { get; set; }
public virtual ICollection<Delivery> Deliveries { get; set; }
}
public class Delivery
{
[Key]
public int DeliveryId { get; set; }
public string Description { get; set; }
public bool IsDelivered { get; set; }
[IgnoreDataMember]
public virtual Customer Customer { get; set; }
public virtual int CustomerId { get; set; }
}
I posted a working solution to your problem in a different question: https://stackoverflow.com/a/10010695/1226140
I am revisiting RavenDB after a brief experiment quite a while ago. At the moment I'm considering document design which is nested 3 levels deep, i.e.
public class UserEvent
{
public UserEvent()
{
Shows = new List<Show>();
}
public readonly string IdPrefix = "Events/";
public string Id { get; set; }
public string Title { get; set; }
public List<Show> Shows { get; set; }
}
public class Show
{
public Show()
{
Entries = new List<ShowEntry>();
}
public readonly string IdPrefix = "Shows/";
public string Id { get; set; }
public string EventId { get; set; }
public string Name { get; set; }
public DateTime Date { get; set; }
public List<ShowEntry> Entries { get; set; }
}
public class ShowEntry
{
public readonly string IdPrefix = "ShowEntries/";
public string Id { get; set; }
public string DogId { get; set; }
public string OwnerName { get; set; }
public EntryClass Class { get; set; }
}
First of all, is this a sensible design? A UserEvent generally has a few (less than 6) Show, but a Show can have between tens to hundreds of ShowEntry. I have included DogId in ShowEntry but maybe later I will change it to a property of Dog type. A Dog is of a particular Breed, and a Breed belongs to a Group. The Dog side of the story will have to be another question but for now I'm interested in the UserEvent side.
If my documents are designed this way can I use the Patching API to add items into the Entries collection within a Show? I would like to have an index which will summarise Entries based on Dog properties. Will indexes get processed if an a document is patched?
Your design certainly looks sensible from an outside perspective. The big question you need to ask yourself is, "What do you plan on querying a majority of the time?"
For instance, Show seems to be a fairly common object that would benefit from being an Aggregate Root (from Domain Driven Design). I find that when organizing my documents, the most important question is, "how often do you plan on querying the object."
To answer your last question, Patching should definitely causing re-indexing.
I'm using NHibernate in my web app and it is mapped with my database. I have a model, somthing like this:
public class Company {
public virtual string Name { get; set; }
public virtual IList<Employee> Employeers { get; set; }
}
public class Employee {
public virtual string Name { get; set; }
public virtual DateTime Birthday { get; set; }
/* other properties */
public virtual Company Company { get; set; }
}
PS: it's not real model but it works for my samples/doubts...
I'm using HQL to get my objects and I'd like to know if is there any way to:
1) Get a Company object and fill the Employeers Colletion with Top 10 Employeers Ordered by Birthday Desc ?
2) Is there any way to, when collection is filled, fill it with only some fields like Name and Birthday? I have a lot of properties that I won't use in my view. I can create a DTO for this but I don't know how to do!
Thanks
Persistent collections and entities represent the current state; they can't have just a part of that (think about it: if they did, how would NH track changes?)
So, in both cases, the answer is queries and DTOs. You can easily retrieve the data you need with HQL:
class EmployeeNameAndBirthDay
{
public string Name { get; set; }
public DateTime Birthday { get; set; }
}
public IList<EmployeeNameAndBirthDay> GetTopEmployees(Company company)
{
return session.CreateQuery(#"
select Name as Name,
Birthday as Birthday
from Employee
where Company = :company
order by Birthday desc
")
.SetParameter("company", company)
.SetMaxResults(10)
.SetResultTransformer(
Transformers.AliasToBean<EmployeeNameAndBirthDay>())
.List<EmployeeNameAndBirthDay>();
}