How to POST / PATCH for a many-to-many relationship object in Azure Mobile Services?

I followed a Field Engineer sample project from Windows Development Center to maintain a mapping of many-to-many relationships on my model. I was worried about how to insert records into many-to-many relationships.

Take my model as an example:

An organization can have many users .

A user can belong to many organizations .

My model class for User looks like this:

public class User
{
    public User()
    {
        this.Organizations = new HashSet<Organization>();
    }

    public int Id { get; set; }
    public string Email { get; set; }
    public string Password { get; set; }
    public string PasswordSalt { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public bool Active { get; set; }
    public string Picture { get; set; }
    public string PictureMimeType { get; set; }
    public bool Confirmed { get; set; }
    public string ConfirmationKey { get; set; }

    [JsonIgnore]
    public virtual ICollection<Organization> Organizations { get; set; }
}

      

        
        
        
      

    

My UserDTO class:

public class UserDTO : EntityData
{
    public string Email { get; set; }
    public string Password { get; set; }
    public string PasswordSalt { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public bool Active { get; set; }
    public string Picture { get; set; }
    public string PictureMimeType { get; set; }
    public bool Confirmed { get; set; }
    public string ConfirmationKey { get; set; }

}

      

        
        
        
      

    

My Organization class:

public class Organization
{
    public Organization()
    {
        this.Users = new List<User>();
    }

    public string Id { get; set; }
    public string Title { get; set; }
    public string LegalName { get; set; }
    public string TaxReference { get; set; }

    [JsonIgnore]
    public virtual ICollection<User> Users { get; set; }
}

      

        
        
        
      

    

My OrganizationDTO class:

public class OrganizationDTO : EntityData
{
    public string Title { get; set; }
    public string LegalName { get; set; }
    public string TaxReference { get; set; }

    public virtual ICollection<UserDTO> Users { get; set; }
}

      

        
        
        
      

    

With these classes in mind, I created controller classes, I mapped the DTO and Model classes using AutoMapper like this:

cfg.CreateMap<Organization, OrganizationDTO>()
   .ForMember(organizationDTO => organizationDTO.Id, 
      map => map.MapFrom(organization => MySqlFuncs.LTRIM(MySqlFuncs.StringConvert(organization.Id))))
   .ForMember(organizationDTO => organizationDTO.Users, 
      map => map.MapFrom(organization => organization.Users));

 cfg.CreateMap<OrganizationDTO, Organization>()
    .ForMember(organization => organization.Id, 
       map => map.MapFrom(organizationDTO => MySqlFuncs.LongParse(organizationDTO.Id)))
    .ForMember(organization => organization.Users, 
       map => map.Ignore());

      

        
        
        
      

    

Using the Fluent API, I have defined the relationship between these two entities using the EntityTypeConfiguration class , for example:

public class UserEntityConfiguration : EntityTypeConfiguration<User>
{
    public UserEntityConfiguration()
    {
        this.Property(u => u.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
        this.HasMany<Organization>(u => u.Organizations).WithMany(o => o.Users).Map(uo =>
        {
            uo.MapLeftKey("UserId");
            uo.MapRightKey("OrganizationId");
            uo.ToTable("OrganizationsUsers");
        });
    }
}

      

        
        
        
      

    

I created a TableController class to hanlde UserDTO and OrganizationDTO . I have no problem inserting new users or new organizations, but endpoints from what I know each TableController class allows me to add users or organizations individually.

To create a record in the OrganizationUser table, how can I achieve this?

I thought that a PATCH request should be the way to do it, but is it correct? Do I have to define a TableController for this? How can I open the Insert, Update, Select and Delete elements from this relationship? What would be the JSON to send to endpoints?

EDIT 1

I tried to set PATCH property Users in the organization like this:

url: serviceUrl / tables / Organization / 1

JSON body:

{
  "users": [
    {
      "id": "1"
    }
  ]
}

      

        
        
        
      

    

But this gave me an error:

The type of one of the primary key values ​​does not match the type defined in the object. See Inner Exception for details. Parameter name: keyValues

Inner Exception:

The argument types "Edm.Int32" and "Edm.String" are not compatible for this operation. Next to the WHERE predicate, row 1, column 78.

It seems like I need to map the string I am posting to the connection table created with the Fluent API, if I'm not wrong, but how do I map the connection table defined with the Fluent API? Is this the PATCH way to do it? Or is there another way?