CODEWITHSUNDEEP
c#sqlitesqlite-net
SunnySydeUp
SunnySydeUp

Reputation: 6790

Creating a ManyToMany relationship between two models

I'm new to creating a Windows Store app and it requires a use of a database. I've settled for sqlite and am using the sqlite-net package. However, I'm unsure of how to create a m2m relationship between two models.

class ModelA
{
     [PrimaryKey, AutoIncrement]
     public int Id { get; set; }
     public string name { get; set; }
     <relationship to ModelB>
} 


class ModelB
{
     [PrimaryKey, AutoIncrement]
     public int Id { get; set; }
     public string name { get; set; }
}

Would I have to use a List? or a byte[]? How can I guarantee the property will be constrained to ModelB?

Upvotes: 9

Views: 3882

Answers (1)

NeddySpaghetti
NeddySpaghetti

Reputation: 13495

You might be able to use sqlite-net-extensions, it has a ManyToMany attribute that seems perfect for your needs. This is an example of its use from their website.

public class Student
{
    [PrimaryKey, AutoIncrement]
    public int StudentId { get; set; }

    public string Name { get; set; }
    public int Age { get; set; }

    [ManyToMany(typeof(StudentsGroups))]
    public List<Group> Groups { get; set; }

    public int TutorId { get; set; }
    [ManyToOne("TutorId")] // Foreign key may be specified in the relationship
    public Teacher Tutor { get; set; }
}

public class Group
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    public string GroupName { get; set; }

    [ForeignKey(typeof(Teacher))]
    public int TeacherId { get; set; }

    [ManyToOne]
    public Teacher Teacher { get; set; }

    [ManyToMany(typeof(StudentsGroups))]
    public List<Student> Students { get; set; } 
}

public class StudentGroups
{
    [ForeignKey(typeof(Student))]
    public int StudentId { get; set; }

    [ForeignKey(typeof(Group))]
    public int GroupId { get; set; }
}

Upvotes: 15

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