One to Many Mapping in Fluent Nhibernate

Question

I am working on Fluent Nhibernate and I am getting the following error:

"Cannot insert the value NULL into column 'EmailAccountId', table 'NopCommerceNew123.dbo.QueuedEmail'; column does not allow nulls. INSERT fails.\\r\\nThe statement has been terminated."} could not insert: [Nop.Core.Domain.Messages.QueuedEmail][SQL: INSERT INTO QueuedEmail ([Priority], [From], FromName, [To], ToName, CC, Bcc, [Subject], Body, AttachmentFilePath, AttachmentFileName, CreatedOnUtc, SentTries, SentOnUtc, EmailAccountId) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?); select SCOPE_IDENTITY()]

Please let me know about the error in this.Thanks.

Here Are My Classes and mappings:

QueueEmail.cs

public  partial class QueuedEmail : BaseEntity
{
    /// <summary>
    /// Gets or sets the priority
    /// </summary>
    public virtual  int Priority { get; set; }

    /// <summary>
    /// Gets or sets the From property
    /// </summary>
    public virtual  string From { get; set; }

    /// <summary>
    /// Gets or sets the FromName property
    /// </summary>
    public virtual  string FromName { get; set; }

    /// <summary>
    /// Gets or sets the To property
    /// </summary>
    public virtual  string To { get; set; }

    /// <summary>
    /// Gets or sets the ToName property
    /// </summary>
    public virtual  string ToName { get; set; }

    /// <summary>
    /// Gets or sets the CC
    /// </summary>
    public virtual  string CC { get; set; }

    /// <summary>
    /// Gets or sets the Bcc
    /// </summary>
    public virtual  string Bcc { get; set; }

    /// <summary>
    /// Gets or sets the subject
    /// </summary>
    public virtual  string Subject { get; set; }

    /// <summary>
    /// Gets or sets the body
    /// </summary>
    public virtual  string Body { get; set; }

    /// <summary>
    /// Gets or sets the attachment file path (full file path)
    /// </summary>
    public virtual  string AttachmentFilePath { get; set; }

    /// <summary>
    /// Gets or sets the attachment file name. If specified, then this file name will be sent to a recipient. Otherwise, "AttachmentFilePath" name will be used.
    /// </summary>
    public virtual  string AttachmentFileName { get; set; }

    /// <summary>
    /// Gets or sets the date and time of item creation in UTC
    /// </summary>
    public virtual  DateTime CreatedOnUtc { get; set; }

    /// <summary>
    /// Gets or sets the send tries
    /// </summary>
    public virtual  int SentTries { get; set; }

    /// <summary>
    /// Gets or sets the sent date and time
    /// </summary>
    public virtual  DateTime? SentOnUtc { get; set; }

    /// <summary>
    /// Gets or sets the used email account identifier
    /// </summary>
    public virtual  int EmailAccountId { get; set; }

    /// <summary>
    /// Gets the email account
    /// </summary>
    public virtual  EmailAccount EmailAccount { get; set; }
}

EmailAccount.cs

public  partial class EmailAccount : BaseEntity
{
    /// <summary>
    /// Gets or sets an email address
    /// </summary>
    public virtual  string Email { get; set; }

    /// <summary>
    /// Gets or sets an email display name
    /// </summary>
    public virtual  string DisplayName { get; set; }

    /// <summary>
    /// Gets or sets an email host
    /// </summary>
    public virtual  string Host { get; set; }

    /// <summary>
    /// Gets or sets an email port
    /// </summary>
    public virtual  int Port { get; set; }

    /// <summary>
    /// Gets or sets an email user name
    /// </summary>
    public virtual  string Username { get; set; }

    /// <summary>
    /// Gets or sets an email password
    /// </summary>
    public virtual  string Password { get; set; }

    /// <summary>
    /// Gets or sets a value that controls whether the SmtpClient uses Secure Sockets Layer (SSL) to encrypt the connection
    /// </summary>
    public virtual  bool EnableSsl { get; set; }

    /// <summary>
    /// Gets or sets a value that controls whether the default system credentials of the application are sent with requests.
    /// </summary>
    public virtual  bool UseDefaultCredentials { get; set; }


    public virtual ICollection<QueuedEmail> QueueEmail { get; set; }

    /// <summary>
    /// Gets a friendly email account name
    /// </summary>
    public virtual  string FriendlyName
    {
        get
        {
            if (!String.IsNullOrWhiteSpace(this.DisplayName))
                return this.Email + " (" + this.DisplayName + ")";
            return this.Email;
        }
    }

QueuedEmailMap.cs:

 public class QueuedEmailMap : ClassMap<QueuedEmail>
 {
        public QueuedEmailMap()
        {
            Table("QueuedEmail");
            LazyLoad();
            Id(x => x.Id).GeneratedBy.Identity().Column("Id");          
            Map(x => x.Priority).Column("[Priority]").Not.Nullable().Precision(10);
            Map(x => x.From).Column("[From]").Not.Nullable().Length(500);
            Map(x => x.FromName).Column("FromName").Length(500);
            Map(x => x.To).Column("[To]").Not.Nullable().Length(500);
            Map(x => x.ToName).Column("ToName").Length(500);
            Map(x => x.CC).Column("CC").Length(500);
            Map(x => x.Bcc).Column("Bcc").Length(500);
            Map(x => x.Subject).Column("[Subject]").Length(1000);
            Map(x => x.Body).Column("Body");
            Map(x => x.AttachmentFilePath).Column("AttachmentFilePath");
            Map(x => x.AttachmentFileName).Column("AttachmentFileName");
            Map(x => x.CreatedOnUtc).Column("CreatedOnUtc").Not.Nullable();
            Map(x => x.SentTries).Column("SentTries").Not.Nullable().Precision(10);
            Map(x => x.SentOnUtc).Column("SentOnUtc");
            //References(x => x.EmailAccount).Class<EmailAccount>().Columns("EmailAccountId");
              References(x => x.EmailAccount).Column("EmailAccountId").Not.Nullable().Cascade.All();
        }
    }

EmailAccountMap.cs:

public class EmailAccountMap : ClassMap<EmailAccount>
{
    public EmailAccountMap()
    {   Table("EmailAccount");
        LazyLoad();
        Id(x => x.Id).GeneratedBy.Identity().Column("Id");
        Map(x => x.Email).Column("Email").Not.Nullable().Length(255);
        Map(x => x.DisplayName).Column("DisplayName").Length(255);
        Map(x => x.Host).Column("Host").Not.Nullable().Length(255);
        Map(x => x.Port).Column("Port").Not.Nullable().Precision(10);
        Map(x => x.Username).Column("Username").Not.Nullable().Length(255);
        Map(x => x.Password).Column("Password").Not.Nullable().Length(255);
        Map(x => x.EnableSsl).Column("EnableSsl").Not.Nullable();
        Map(x => x.UseDefaultCredentials).Column("UseDefaultCredentials").Not.Nullable();

    }
}

Answer 1

The solution here would be to assign EmailAccount of the QueuedEmail instance, when adding it into the collection of QueuedEmails . This should be the code:

// method somewhere in the 'EmailAccount' definiton
public void AddEmail(QueuedEmail email)
{
    this.QueueEmail.Add(email)
    email.EmailAccount = this;
}

this will correctly assign the value "EmailAccount" into the column "EmailAccountId" during the INSERT.

The reason is: we declared the collection of QueueEmail as inverse

HasMany<QueuedEmail>(x => x.QueueEmail)
  .KeyColumn("EmailAccountId")
  .Inverse() // here we say inverse
  .Cascade.All(); 

And inverse is a sign for NHibernate: the child does know about its parent reference - child will care about self (because it has enough information) . And with the adjustment above (assigning the parent) all will work.

EDIT: how to fix the next issue:

"not-null property references a null or transient value QueuedEmail.EmailAccount."

The problem is, that when we call: session.Save(queuedEmail) the queuedEmail instance must have set the reference EmailAccount . It is not enough to set integer EmailAccountId ! Why? because it is not mapped. And there is in fact solution

So, if we always can be sure, that we have the EmailAccountId , we can use this mapping:

public class QueuedEmailMap : ClassMap<QueuedEmail>
{
    public QueuedEmailMap()
    {
        ...
        // this property will be WRITABLE
        Map(x => x.x.EmailAccountId)
          .Column("EmailAccountId")

        // this one will be readonly
        References(x => x.EmailAccount)
          .Column("EmailAccountId")
          .Not.Nullable()
          .Cascade.All()
          .Not.Insert() // this is the setting
          .Not.Update()
          ;
    ...

From this moment, we can set just the reference Id and all will work.

NOTE: I do also use the doubled mapping (Id and Reference), but the readonly is the int Id

Answer 2

You can add the property twice like Radim says. Or delete the property EmailAccountId from QueuedEmail class and just add this to your mapping:

public class EmailAccountMap : ClassMap<EmailAccount>
{
    public EmailAccountMap()
    {
        // your code

        HasMany<QueuedEmail>(x => x.QueueEmail)
           .KeyColumn("EmailAccountId")
           .Inverse()
           .Cascade.All(); 
    }
}
public class QueuedEmailMap : ClassMap<QueuedEmail>
{
    public QueuedEmailMap()
    {
        // your code

        References(x => x.EmailAccount)
          .Column("EmailAccountId")
          .Not.Nullable();
    }
}

Don't forget call:

session.Save(emailAccount)