I am developing an ASP.Net Core Web API using EF Core Code First (C#) and SQL Server.
I have a fairly simple scenario which I just cannot figure out. I have a Form entity and a Site entity. Each Form can have many Sites and each Site can be in many Forms. To enable this I have a SiteForm joining table. For each Site associated with a Form there is a Leaving Date field. So my SiteForm class looks like this:
public class SiteForm
{
public Guid SiteId { get; set; }
public Site Site{ get; set; }
public Guid FormId { get; set; }
public Form Form{ get; set; }
public DateTime? LeavingDate { get; set; }
}
My Form's Data Transfer Object (FormDto) is as follows:
public class FormDto
{
public Guid Id { get; set; }
...
public ICollection<LinkedSiteDto> LinkedSites { get; set; }
= new List<LinkedSiteDto>();
}
And my LinkedSiteDto is like this:
public class LinkedSiteDto
{
public Guid Id { get; set; }
public string Name { get; set; }
public string Ident { get; set; }
public DateTime? LeavingDate { get; set; }
}
Having populated the database I can get the Sites for each Form using the following mapping:
CreateMap<Form, FormDto>()
.ForMember(dto => dto.LinkedSites, opt => opt.MapFrom(
form => form.SiteForms.Select(sf => sf.Site).ToList()));
I just cannot figure out how I would include the LeavingDate value from each joining table entry? Any suggestions would be very gratefully received.
Related
I have built a simple survey-tool using MVC 3 with only 1 layer (MVC). I regret this now. All my database access and mapping is handled in the controllers, and some other mapping classes.
I would like to switch over to using three layers:
Presentation (MVC)
Business Logic
Data / Persistence (EF)
I am using the Entity Framework to handle everything with the database. The entity framework creates it's own domain classes. Where should the mapping between the Models that MVC uses and the models that EF creates go?
If the mapping is in the business layer, is there a need for the Models folder in the MVC project?
A survey-question consists of the Question itself, Rows and Columns. Theese are the models that i use:
public class Question {
public int Question_ID { get; set; }
public Boolean Condition_Fullfilled;
[Required(ErrorMessage = "Dette felt er påkrævet")]
public String Question_Wording { get; set; }
public String Question_Type { get; set; }
[Required(ErrorMessage = "Dette felt er påkrævet")]
public String Question_Order { get; set; }
public String Left_scale { get; set; }
public String Right_scale { get; set; }
public int Scale_Length { get; set; }
public String Left_Scale_HelpText { get; set; }
public String Right_Scale_HelpText { get; set; }
public Boolean Visible { get; set; }
public Boolean IsAnswered { get; set; }
public String Question_HelpText { get; set; }
public int Category_ID { get; set; }
}
public class MatrixColumns
{
public int Column_ID { get; set; }
public int Column_Number { get; set; }
public String Column_Description { get; set; }
public Boolean IsAnswer { get; set; }
public int? Procent { get; set; }
public bool Delete { get; set; }
public bool Visible { get; set; }
public int? Numbers { get; set; }
public String Help_Text { get; set; }
}
public class MatrixRows
{
public bool Delete { get; set; }
public bool Visible { get; set; }
public int Row_Id { get; set; }
public String Row_Number { get; set; }
public String Row_Description { get; set; }
public String Special_Row_CSS { get; set; }
public String Help_Text { get; set; }
// Dette er summen af procenterne af alle kolonner i rækken
public int RowSum { get; set; }
}
All the data for theese models is retrieved in the Controller, based upon a QuestionID, and mapped to a ViewModel that looks like this:
public class ShowMatrixQuestionViewModel : Question
{
public Dictionary<MatrixRows, List<MatrixColumns>> columnrow { get; set; }
public List<MatrixColumns> columns { get; set; }
public List<MatrixRows> rows { get; set; }
public ShowMatrixQuestionViewModel()
{
columns = new List<MatrixColumns>();
rows = new List<MatrixRows>();
columnrow = new Dictionary<MatrixRows, List<MatrixColumns>>();
}
}
So when i want to send a ShowMatrixQuestionViewModel to a View from my Controller, what is the route i should take?
This is my suggestion:
-> Controller calls a method in the business layer called
public ShowMatrixViewModel GetQuestion(int QuestionID) {}
-> GetQuestion calls the following methods in the data layer:
public Question GetQuestion(int QuestionId) {}
public MatrixRows GetRows(int QuestionId) {}
public MatrixColumns GetColumns(int id) {}
-> Entity framework returns "pure" objects, which i want to map over to the ones i posted above
-> GetQuestion calls methods to map the EF models to my own models
-> Last GetQuestion calls a method that maps the Questions, Rows and Columns:
ShowMatrixQuestionViewModel model = MapShowMatrixQuestionViewModel(Question, MatrixRows, MatrixColumns)
return model;
Is this correct?
Thanks in advance
To answer the first part of your question:
"Where should the mapping between the Models that MVC uses and the models that EF creates go?"
The answer is that the models MVC uses are the models created by the EF. Your EF tool in the ASP.NET MVC project is either Linq to SQL Classes or the ADO.NET Entity Framework Model. You should create these inside the Models folder in your project and they provide your data / persistence (EF).
So I decided to go with the code first/DbContext approach, but already have an existing database file. Nothing complex, so I am thinking I can just create the DbContext derived container class with DbSets for the respective POCO's, create the connection string to my database and I should be set. However I believe I am having difficulties properly declaring the properties in my entity classes since I am getting errors when trying access an object through the navigational properties. Usually telling me Object reference not set to an instance of an object when I try context.Products.Find(1).Category.CATNAME; etc. Also tried declaring the collection properties with virtual keyword to no avail.
Some specifics of the database schema are:
In Categories table the PCATID is a foreign key to the CategoryID in
the same Categories table and can be null.
Both CategoryID and RootCategoryID in Products table can be null and
are both foreign keys to CategoryID in the Categories table.
I am testing things at the moment but will be setting a lot of the fields to non null types eventually.
Here are my entity POCO's and the entity Dbset container class:
public class Category
{
[Key]
public int CategoryID { get; set; }
public string CATNAME { get; set; }
public int PCATID { get; set; }
public ICollection<Category> Categories { get; set; }
public ICollection<Product> Products { get; set; }
}
public class Product
{
[Key]
public int ProductID { get; set; }
public int CategoryID { get; set; }
public int RootCategoryID { get; set; }
public string Name { get; set; }
public string ShortDescription { get; set; }
public string LongDescription { get; set; }
public string Keywords { get; set; }
public decimal ListPrice { get; set; }
public Category Category { get; set; }
}
public class EFDbContext: DbContext
{
public DbSet<Product> Products { get; set; }
public DbSet<Category> Categories { get; set; }
}
You need to make PCATID a nullable property as you have said it can be null. Make all those navigation properties and collection properties virtual. EF will not be able to detect the category hierarchy so you have use either attributes or fluent API to configure that.
public class Category
{
[Key]
public int CategoryID { get; set; }
public string CATNAME { get; set; }
[ForeignKey("ParentCategory")]
public int? PCATID { get; set; }
[InverseProperty("Categories")]
public virtual Category ParentCategory { get; set; }
[InverseProperty("ParentCategory")]
public virtual ICollection<Category> Categories { get; set; }
public virtual ICollection<Product> Products { get; set; }
}
Requirements for Creating POCO Proxies
Everything looks ready for POCO but Lazy Loading isn't sorted out at this point. By default LL is on, but in order to enable lazy loading, the Category property must be Virtual (a proxy is created that catches the reference and loads the data). If you don't want lazy loading then disable it in your EFDbContext constructor.
So your options are:
public virtual Category Category { get; set; }
or
public class EFDbContext: DbContext
{
public static EFDbContext()
{
LazyLoadingEnabled = false
}
...
}
You'd probably want to do the first one...
Are you certain you really want to use Code First? Or do you just want to use DbContext and DbSet? You can get the same benefits with Database First, using DbContext and DbSet. Since you already have a database, it's generally a lot simpler.
See: http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-model-amp-database-first-walkthrough.aspx
The only difference between Code First and Database First with DbContext is that Code first uses the fluent mapping model, while Database First uses an .edmx file. Maintaining the .edmx is much easier with an existing database.
If you're bound and determined to use Code First, then I suggest getting the Entity Framework Power Tools CTP1 and reverse engineering your database to Code First.
I agree with #Eranga about class Category (+1 to #Eranga).
public class Category {
[Key]
public int CategoryID { get; set; }
public string CATNAME { get; set; }
[ForeignKey("ParentCategory")]
public int? PCATID { get; set; }
[InverseProperty("Categories")]
public virtual Category ParentCategory { get; set; }
[InverseProperty("ParentCategory")]
public virtual ICollection<Category> Categories { get; set; }
public virtual ICollection<Product> Products { get; set; }
}
And you also have problem with your Linq query:
context.Products.Find(1).Category.CATNAME;
EF return data only from tables that you request with Include or you use this tables in functions.
With this code all work:
db.Products
.Include(p => p.Category) // here I demand to load data from Category table
.First(p => p.ProductID == 3)
.Category
.CATNAME;
I am working on a asp.net mvc3 demo app with razor that is hosted on http://portfolio-6.apphb.com/Projects
I have mvc scaffolding, Poco objects as entities and mvc scaffolding running.
public class Project
{
public int ProjectId { get; set; }
[Required(ErrorMessage="please enter name")]
public string Name { get; set; }
public string Url { get; set; }
public DateTime CreatedOn { get; set; }
public DateTime UpdatedOn { get; set; }
public bool isFeatured { get; set; }
public bool isDisabled { get; set; }
public int GroupId { get; set; }
public virtual Group Group { get; set; }
[Required(ErrorMessage="Please select atleast one tag")]
public virtual ICollection<Tag> Tags { get; set; }
}
public class Tag
{
public int TagId { get; set; }
public string Name { get; set; }
public DateTime CreatedOn { get; set; }
public DateTime UpdatedOn { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
public class Group
{
public int GroupId { get; set; }
public string Name { get; set; }
public DateTime CreatedOn { get; set; }
public DateTime UpdatedOn { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
First Problem
From above code you can see I have many to many relation between Project and Tag entities.
Now I have mange to implement New project feature with one bug that is Tags property of Project marked as required but client site validation is not working if you don't select any tag.
Second Problem
Once a project is created with mutliple tags if you decide to edit it how to show the tags selected that are associated with the project???
You can find complete source code at https://github.com/najamsk/PortfolioManger
I have manage to make validation work and tags are now getting selected while editing a project.
But now I run into another problem lets say I create a new project with tag "asp.net" and later I edit project and choose one tag only "wordpress". Now if i post form model binding works but my context cant update tags collection property of the project? It seems to me it entity framwork making problem here when it finds a complex type property for my Project entity?
public void InsertOrUpdate(Project project)
{
if (project.ProjectId == default(int)) {
// New entity
foreach (var tag in project.Tags)
{
context.Entry(tag).State = EntityState.Unchanged;
}
context.Projects.Add(project);
}
else {
// Existing entity
//every property of project entity is
//getting updated only tags property left out :(
context.Entry(project).State = EntityState.Modified;
}
}
This is a question about Models, ASP.NET MVC 3 and relationships. I'm using the code-first approach.
Imagine this simple typical scenario of an User with its Blog Posts:
public class User
{
public virtual int UserId { get; set; }
public virtual string Nickname { get; set; }
public virtual List<Post> Posts { get; set; }
}
public class Post
{
public virtual int PostId { get; set; }
public virtual string BlogText { get; set; }
}
I made it very very simple.
Well. When I create a controller using the Controller with Read/Write actions and views using Entity Framework, the collection of Posts is not considered. It's being ignored. So, I can't get this relationship to work.
If, in place of the collection, there was a single object (public virtual string Email, for example) it works normally.
I'm asking myself and to you:
Why
How do I put references to collections in my model?
It should be a simple task, I really can't understand why it doesn't work.
Thank you.
POCO should look like below to have one-to-many relationship:
public class Post
{
public int Id { get; set; }
public string BlogText { get; set; }
public virtual User User { get; set; }
}
public class User
{
public int Id { get; set; }
public string Nickname { get; set; }
public virtual ICollection<Post> Posts { get; set; }
}
I'm having trouble passing view information from my Get/Create action to my view. Here are my three model classes;
public class Competition
{
public int Id { get; set; }
public int CompetitionId { get; set; }
public string Name { get; set; }
public string Prize { get; set; }
}
public class CompetitionEntry
{
public int Id { get; set; }
public int CompetitionEntryId { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public int CompetitionId { get; set; }
}
public class CompetitionEntryViewModel
{
public int Id { get; set; }
public Competition Competitions { get; set; }
public int CompetitionId { get; set; }
public string Name { get; set; }
public string Email { get; set; }
}
Here is my Get/Create action in CompetitionEntry Controller;
public ActionResult Create(int id)
{
CompetitionEntryViewModel competitionentryviewmodel = db.CompetitionEntriesView.Find(id);
return View(competitionentryviewmodel);
}
I know this doesn't work. The id parameter goes into the URL fine. How to I get access to my Competition class in th Get action? I need to be able to show the competion name on my Create Competition entry view.
Thanks in advance!
public ActionResult Create(int id)
{
var data = db.CompetitionEntriesView.Find(id);
CompetitionEntryViewModel competitionentryviewmodel = new CompetitionEntryViewModel();
competitionentryviewmodel.CompetitionName = data.Name;
return View(competitionentryviewmodel);
}
What you are trying to do is build an object graph and display it through a view model. In order to do this, you need to map your domain model(s) to your view model.
You can do the mapping yourself by writing a lot of code (re-inventing the wheel), or, you could consider using third party tools to do this for you. I recommend you use an AutoMapper as it is very simple to use imo.
The other problem is that your view model contains a domain model. This is likely to cause you a lot of headache in near future. If I were you, I would replace Competition with CompetitionViewModel.
I would also consider creating a view model for a list of competitions, i.e. CompetitionsViewModel. Look into partial views to see how you can display a list of competitions.
Good luck