one to many relationship ef core

Successful Sloth answered on December 3, 2020 Popularity 10/10 Helpfulness 3/10

answer one to many relationship ef core

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one to many relationship ef core

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// 1:M
// ONE company has MANY employees

public class Company
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Employee> Employees { get; set; }
}
public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Company Company { get; set; }
}

Popularity 10/10 Helpfulness 3/10 Language csharp

Source: www.learnentityframeworkcore.com

Tags: c# core one-to-many relationship

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Contributed on Dec 03 2020

Successful Sloth

0 Answers Avg Quality 2/10

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// Relationship format for traditional Many to Many (You have to use Many to Many with Data annotations for additional variables on the join table)

using System;
using System.Collections.Generic;
using Microsoft.EntityFrameworkCore;

namespace EFGetStarted
{
    public class Context : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder options)
            => options.UseSqlite(@"Data Source=blogging.db");

        protected override void OnModelCreating(ModelBuilder modelBuilder) { }
    
        public DbSet<GarageDoorModel> GarageDoorModels { get; set; }
        public DbSet<Section> Sections { get; set; }
    }

    public class GarageDoorModel
    {
        public int GarageDoorModelId { get; set; }
        public string ModelName { get; set; }
        
        public ICollection<Section> Sections { get; set; }
    }

    public class Section
    {
        public int SectionId { get; set; }
        public string SectionName { get; set; }
        public string Key { get; set; }
        
        public ICollection<GarageDoorModel> GarageDoorModels { get; set; }
    }
}

//Using the Data

using System;
using System.Collections.Generic;
using System.Linq;
using EFGetStarted;

namespace SchoolCourse
{
    internal class Program
    {
        private static void Main()
        {
            using var db = new Context();
            
            Console.WriteLine("Inserting new records");

            var modelName = "X";
            
            var sections = new List<Section> {
                new Section
                {
                    SectionName = "Engine",
                    Key = "front_engine"
                },
            };

            db.Add(new GarageDoorModel {ModelName = modelName});
            db.SaveChanges();

            var gdm = db.GarageDoorModels.First(g => g.ModelName == modelName);
            gdm.Sections = sections;

            db.SaveChanges();

            // Read
            var new_gdm = db.GarageDoorModels.First(g => g.ModelName == modelName);
            Console.WriteLine(new_gdm.Sections);
            
            foreach (var VARIABLE in new_gdm.Sections)
            {
                Console.WriteLine(VARIABLE.Key);
            }
            
        }
    }
}

//package list

Project 'SchoolCourse' has the following package references
   [net5.0]:
   Top-level Package                              Requested   Resolved
   > Microsoft.EntityFrameworkCore.Design         5.0.5       5.0.5
   > Microsoft.EntityFrameworkCore.Sqlite         5.0.5       5.0.5
   > Microsoft.EntityFrameworkCore.SqlServer      5.0.5       5.0.5

Popularity 10/10 Helpfulness 2/10 Language csharp

Source: Grepper

Tags: c# c

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Contributed on May 05 2021

Juice WRLD

0 Answers Avg Quality 2/10

one to many relationship ef core

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