// NMemory

// Doc: https://nmemory.net/constraints

​

// @nuget: NMemory

​

using System;

using System.Linq;

using NMemory;

using NMemory.Indexes;

using NMemory.Tables;

using NMemory.Constraints;

public class Program

{

    public static void Main()

    {

        MyDatabase myDatabase = new MyDatabase();

​

        try

        {

            // not good because NCharConstraint 

            myDatabase.Groups.Insert(new Group() {Name = null});

        }

        catch

        {

            myDatabase.Groups.Insert(new Group() {Name = "12345"});

            // Id not use because IdentitySpecification

            myDatabase.Groups.Insert(new Group() {Id = 8, Name = "NotNull"});

        }

​

        FiddleHelper.WriteTable("All Groups", myDatabase.Groups.ToList());

    }

    public class MyDatabase : Database

    {

        public MyDatabase()

        {

            var members = this.Tables.Create<Member, int>(x => x.Id);

            var groups = this.Tables.Create<Group, int>(x => x.Id, new IdentitySpecification<Group>(x => x.Id, 1, 1));

​

            this.Members = members;

            this.Groups = groups;

​

            RelationOptions options = new RelationOptions(

                cascadedDeletion: true);

​

            var peopleGroupIdIndex = members.CreateIndex(

                new RedBlackTreeIndexFactory(),

                p => p.GroupId);

​

            this.Tables.CreateRelation(

                groups.PrimaryKeyIndex,

                peopleGroupIdIndex,

                x =>  x ?? -1,

                x => x,

                options);

            groups.Contraints.Add(new NotNullableConstraint<Group, string>(x => x.Name));

        }

​

        public ITable<Member> Members { get; private set; }

​

        public ITable<Group> Groups { get; private set; }

    }

​

    public class Member

    {

        public int Id { get; set; }

​

        public string Name { get; set; }

​

        public int? GroupId { get; set; } 

    }

​

    public class Group

    {

        public int Id { get; set; } 

​

        public string Name { get; set; }

​

    }

}