Update: At this moment I can assign only one product to Recipe. What I want to do is add access to all products from db in recipe (controller create) - here Im using public int ProductId but it allow to save only one product. I want to choose a few products from this list and save foreign keys in database. photo
I also tried add public List < int > in ProductId but I got error from entity framework.
I will be grateful for any help.
public class Recipe
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
[Required]
public int ProductId { get; set; }
public List<Product> Products { get; set; }
public Recipe()
{
this.Products = new List<Product>();
}
}
public class Product
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
[Required]
public Recipe? Recipes { get; set; }
}
If you want to create a one-to-many relationship you are almost in the correct direction, but you should remove the public int ProductId { get; set; } and re-arrange as like as below example.
Say you have the following classes:
public class Recipe
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
public List<Product> Products { get; set; } = new();
}
public class Product
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
[Required]
public Recipe Recipe { get; set; }
}
You can instantiate and use as per below:
public static void Main()
{
var recipe = new Recipe
{
Name = "My Recipe",
Products = new List<Product>
{
new Product { Name = "Product 1" },
new Product { Name = "Product 2" },
new Product { Name = "Product 3" }
}
};
recipe.Products.ForEach(product =>
{
Console.WriteLine(product.Name);
});
}
It sounds like you are looking for a many-to-many relationship rather than a one-to-many.
If you are using Code-First and EF6 or EF Core 5+ then you can use:
public class Recipe
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
public virtual ICollection<Product> Products { get; set; } = new List<Product>();
}
public class Product
{
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
public virtual ICollection<Recipe> Recipes { get; set; } = new List<Recipe>();
}
To understand what is happening behind the scenes, EF should create a joining table called ProductRecipe or RecipeProduct which contains two FKs. ProductId and RecipeId. These will also form a composite PK for this table. Using this table, EF can associate one product to several recipes while also associating one recipe to the various products. In the object model you get the collection of products for each recipe, and the collection of recipes for each product.
With earlier versions of EF Core you were limited to having to declare this linking entity so you would have something more like:
public class Recipe
{
// ...
public virtual ICollection<ProductRecipe> ProductRecipes { get; set; } = new List<ProductRecipe>();
}
public class Product
{
// ...
public virtual ICollection<ProductRecipe> ProductRecipes { get; set; } = new List<ProductRecipe>();
}
public class ProductRecipe
{
[Key, Column(Order = 0)]
public int ProductId { get; set; }
[Key, Column(Order = 1)]
public int RecipeId { get; set; }
public virtual Product Product { get; set; }
public virtual Recipe Recipe { get; set; }
}
This approach is still an option in the other versions of EF, and is required if you want to support adding any additional fields to the joining table. For instance if you want to track things like CreatedDate/ModifiedDate etc. to record when a product was associated to a recipe etc. To expose that information to an application through EF, EF needs to know about the ProductRecipe as an entity. The trade off is that this approach is "messier" when usually you care about the Products for a Recipe etc. To get a list of products for a recipe you would need:
var products = context.Products
.Where(p => p.ProductRecipes.Any(pr => pr.RecipeId == recipeId)
.ToList();
or
var products = context.Recipies
.Where(r => r.RecipeId == recipeId)
.SelectMany(r => r.ProductRecipies.Select(pr => pr.Product).ToList())
.ToList();
vs. the implied joining table in the first approach:
var produts = context.Recipes
.Where(r => r.RecipeId == recipeId)
.SelectMany(r => r.Products)
.ToList();
... which is arguably easier to read.
Related
I have multiple entities that I would like to share a single "Images" table. For example, products can have a list of images and categories can have a list of images. I would like to use the enum "EntityType" to distinguish what type of entity it is. My solution below doesn't work because there is a foreign key error when I try to insert an image with a EntityId that might exist in Category but not in Product. This makes sense because the solution below isn't taking into account the "EntityType". Are there any recommendations for how I can accomplish this? I know I can use "ProductId", "CategoryId", etc instead of "EntityId" but I will have a lot of entities so I would prefer to not to do it that way.
public class Product
{
public int Id { get; set; }
public List<Image> ProductImages { get; set; }
}
public class Category
{
public int Id { get; set; }
public List<Image> CategoryImages { get; set; }
}
public class Image
{
public int EntityId { get; set; }
public EntityType EntityType { get; set; }
public string ImageUrl { get; set; }
public Product Product { get; set; }
public Category Category { get; set; }
}
modelBuilder.Entity<Product>().ToTable("Product");
modelBuilder.Entity<Category>().ToTable("Category");
modelBuilder.Entity<Image>().ToTable("Image");
modelBuilder.Entity<Image>().HasOne(p => p.Product).WithMany(p => p.ProductImages).HasForeignKey(p => p.EntityId);
modelBuilder.Entity<Image>().HasOne(p => p.Category).WithMany(p => p.CategoryImages).HasForeignKey(p => p.EntityId);
What you're describing is a many-to-many relationship. For that, you'll need an entity to track said relationship:
public class ProductImage
{
[ForeignKey(nameof(Product))]
public int ProductId { get; set; }
public Product Product { get; set; }
[ForeignKey(nameof(Image))]
public int ImageId { get; set; }
public Image Image { get; set; }
}
On your Product/Category classes:
public ICollection<ProductImage> ProductImages { get; set; }
Then, for your fluent config:
modelBuilder.Entity<ProductImage>().HasOne(p => p.Product).WithMany(p => p.ProductImages);
modelBuilder.Entity<ProductImage>().HasOne(p => p.Image).WithMany();
Do the same with your categories.
I have following RecipeModel, IngredientModel and RecipePartModel classes which represent the DTO classes for the frontend user:
public class RecipeModel
{
public Guid Id { get; set; }
public string Name { get; set; }
public string ImageUrl { get; set; }
public string Description { get; set; }
public IEnumerable<RecipePartModel> RecipeParts { get; set; }
}
public class IngredientModel
{
public Guid Id { get; set; }
public string Name { get; set; }
}
public class RecipePartModel
{
public Guid Id { get; set; }
public IngredientModel Ingredient { get; set; }
public string Unit { get; set; }
public decimal Quantity { get; set; }
}
Here are my entity classes:
public class Recipe : BaseEntity
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public Guid Id { get; set; }
public string Name { get; set; }
public string ImageUrl { get; set; }
public string Description { get; set; }
public virtual IEnumerable<RecipePart> RecipeParts { get; set; }
}
public class Ingredient : BaseEntity
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public Guid Id { get; set; }
public string Name { get; set; }
public int Amount { get; set; }
public virtual IEnumerable<RecipePart> RecipeParts { get; set; }
}
public class RecipePart : BaseEntity
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public Guid Id { get; set; }
public Ingredient Ingredient { get; set; }
public Recipe Recipe { get; set; }
public string Unit { get; set; }
public decimal Quantity { get; set; }
}
My question is - how can I map the Recipe to RecipeModel using AutoMapper? I tried something like this but I assume it is bad, because it just join all the RecipeParts for the whole database, am I correct?
public class DomainProfile : Profile
{
public DomainProfile()
{
CreateMap<Ingredient, IngredientModel>().ReverseMap();
CreateMap<Recipe, RecipeModel>()
.ForMember(x => x.RecipeParts, opt => opt.MapFrom(src => src.RecipeParts));
}
}
To answer your question about how to use AutoMapper to map a type to another type, there are many ways of doing this. Documentation is here: http://docs.automapper.org/en/stable/Getting-started.html.
I wrote a console app and got it working in the quickest way I know possible using your code. When I debug this, and check inside recipeModel, it references a list of RecipePartModels with a single RecipePartModel. Inside that RecipePartModel, it references an IngredientModel.
static void Main(string[] args)
{
var profile = new DomainProfile();
Mapper.Initialize(cfg => cfg.AddProfile(profile));
var recipe = new Recipe
{
RecipeParts = new List<RecipePart>
{
new RecipePart()
{
Ingredient = new Ingredient()
}
}
};
var recipeModel = Mapper.Map<Recipe, RecipeModel>(recipe);
Console.ReadKey();
}
To answer your concern about getting all recipes from the database, if you're using Entity Framework, it depends on if you have lazy loading turned on. Lazy loading ensures that, when you get a recipe from the database, the recipe parts will not be loaded. They will only be loaded when you access the recipe part directly later on in the program flow. Lazy loading is turned on by default so this is the default behaviour. If you turn it off, you've enabled eager loading which loads all recipe parts and in turn their ingredient.
This might help: http://www.entityframeworktutorial.net/lazyloading-in-entity-framework.aspx.
There is nothing bad about this mapping. In fact you don't even need the ForMember call as this is the default convention. The mapping will simply convert each element in the entity child collection to a corresponding model object.
Of course, whether you load your entities in an efficient manner is another matter. If you load a large amount of Recipe entities, and lazy load the RecipeParts collections for each, you will have a major "SELECT N+1" problem. But this is not the fault of AutoMapper.
I am using Entity Framework Core 2.0.1 and I have the following models
public class Article
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int Id { get; set; }
[Required]
public string Title { get; set; }
public string Slug { get; set; }
public int Approved { get; set; }
public DateTime ArticleDate { get; set; }
// ... some other fields
public virtual ICollection<ArticleCategoryRelation> ArticleCategoryRelations { get; set; }
}
public class ArticleCategory
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
//... soem other fields
[ForeignKey("ArticleCategoryParent")]
public int? ArticleCategoryParentID { get; set; }
public virtual ArticleCategory ArticleCategoryParent { get; set; }
public virtual ICollection<ArticleCategory> SubCategories { get; set; }
public virtual ICollection<ArticleCategoryRelation> ArticleCategoryRelations { get; set; }
}
public class ArticleCategoryRelation
{
[Column(Order = 0)]
public int ArticleId { get; set; }
public Article Article { get; set; }
[Column(Order = 1)]
public int ArticleCategoryId { get; set; }
public ArticleCategory ArticleCategory {get; set;}
}
Every article belongs to one or more categories. Categories might have parent category.
I want to get from database last two articles (where Approved = 1) with related category details, for each category that belongs to a parent category which id is given as input.
I have tried but with no success. I can't filter results of an .Include() entity. Is it possible... or I don't know how to do it?
All my data are accessed through entity framework with appContext (the context used to get entities from database). Can I achieve what I want through entity framework core (lambda expression is preferred over Linq if possible), or should I use ADO.NET library (which I know how to execute custom queries).
P.S. I want to get data only to show in the view... no edit is needed.
You don't actually need to include here at all, as far as I can tell. Whenever you use data from a nav property, EF will go get the data from that table, as best it can filter it.
var CategoriesUnderParent = AppContext.ArticleCategories
.Where(c => c.ArticleCategoryParent == {parent});
foreach(var category in CategoriesUnderParent)
{
var ArticlesAllowed = category.ArticleCategoryRelations
.Where(acr => acr.Article.Approved == 1).Select(a => a.Article);
var ArticlesPicked = ArticlesAllowed
.OrderByDescending(ar => ar.ArticleDate)
.Take(2);
// Do something with your data
}
work on asp.net mvc5 ef-6.Face problem with many to many relational table data insertion.My classes models are
public class Product
{
public long ProductID { get; set; }
public string ProductName { get; set; }
//navigation property to Supplier
public virtual ICollection<ProductSupplier> ProductSupplier { get; set; }
}
public class Supplier
{
public long SupplierID { get; set; }
public string SupplierName { get; set; }
// navigation property to Product
public virtual ICollection<ProductSupplier> ProductSupplier { get; set; }
}
public class ProductSupplier
{
public long ProductID { get; set; }
public long SupplierID { get; set; }
public virtual Product Product { get; set; }
public virtual Supplier Supplier { get; set; }
public bool IsActive { get; set; }
}
How to insert records on above classes.Will first i need to insert on Product then Supplier then ProductSupplier.
You essentially just have a M2M with a payload here. With that, you'll need to set the Product/Supplier on ProductSupplier before saving that relationship. So something along these lines:
var product = new Product();
var supplier = new Supplier();
var productSupplier = new ProductSupplier
{
Product = product,
Supplier = supplier
};
db.ProductSuppliers.Add(productSupplier);
db.SaveChanges();
For simplicity, I only dealt with the relationships here. Obviously you'd want to intialize/add the other data on the entities. Also, note that it's only necessary to explicitly add the ProductSupplier instance to its DbSet. By virtue of being attached to that instance, the Product and Supplier instances will also be added and saved. You can of course still do that explicitly, instead, if you like.
I have a Project model which has a ProjectLead (one instance of the Person Foreign Key), this works fine. But now I also need to add a collection of People (Project members) referencing the same Person table and I can't get the Entity Framework to generate my database. As soon as I try to add the Fluent API code to create the link table ProjectPerson I get an error - "Schema specified is not valid. Errors: The relationship 'MyApp.WebApi.Models.Person_Projects' was not loaded because the type 'MyApp.WebApi.Models.Person' is not available." I assume this is because of the existing FK relationship already in place with ProjectLead.
Project Model:
public class Project
{
[Key]
public int ProjectId { get; set; }
public string Name { get; set; }
// Foreign Key - Project lead (Person)
public int ProjectLeadId { get; set; }
public virtual Person ProjectLead { get; set; }
// Create many to many relationship with People - Team members on this project
public ICollection<Person> People { get; set; }
public Project()
{
People = new HashSet<Person>();
}
}
Person Model:
public class Person
{
[Key]
public int PersonId { get; set; }
public String Firstname { get; set; }
public String Surname { get; set; }
// Create many to many relationship
public ICollection<Project> Projects { get; set; }
public Person()
{
Projects = new HashSet<Project>();
}
}
DB Context:
public class HerculesWebApiContext : DbContext
{
public DbSet<Person> People { get; set; }
public DbSet<Project> Projects { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// This works fine
modelBuilder.Entity<Project>()
.HasRequired(c => c.ProjectLead)
.WithMany(d => d.Projects)
.HasForeignKey(c => c.ProjectLeadId)
.WillCascadeOnDelete(false);
// Adding these lines to create the link table `PersonProjects` causes an error
//modelBuilder.Entity<Person>().HasMany(t => t.Projects).WithMany(t => t.People);
//modelBuilder.Entity<Project>().HasMany(t => t.People).WithMany(t => t.Projects);
}
}
I gather that perhaps I need to use the InverseProperty attribute, but I am not sure where this should go in this case?
Can you explicitly define your join table? So, define a ProjectPeople relationship and make the code something like this...
public class ProjectPerson{
[Key]
public int ProjectPersonId { get; set; }
[ForeignKey("Project")]
public int? ProjectId {get;set;}
public virtual Project {get;set;}
[ForeignKey("Person")]
public int? PersonId {get;set;}
public virtual Person {get;set;}
public string RelationshipType {get;set;}
}
Then your other 2 classes will look like this...
public class Project
{
[Key]
public int ProjectId { get; set; }
public string Name { get; set; }
// Foreign Key - Project lead (Person)
public int ProjectLeadId { get; set; }
public virtual Person ProjectLead { get; set; }
// Create many to many relationship with People - Team members on this project
public virtual ICollection<ProjectPerson> ProjectPeople { get; set; }
public Project()
{
ProjectPerson = new HashSet<ProjectPerson>();
}
}
And this..
Public class Person
{
[Key]
public int PersonId { get; set; }
public String Firstname { get; set; }
public String Surname { get; set; }
// Create many to many relationship
public virtual ICollection<ProjectPerson> ProjectPeople { get; set; }
public Person()
{
ProjectPerson = new HashSet<ProjectPerson>();
}
}