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POSolution to "An entity object cannot be referenced by multiple instances of IEntityChangeTracker" error
 

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  1. POSolution to "An entity object cannot be referenced by multiple instances of IEntityChangeTracker" error
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    <p>I am attempting to update a member, which has quite a few relationships, but receive an error saying that <code>An entity object cannot be referenced by multiple instances of IEntityChangeTracker</code>. Below are the various models and controllers that I have written. Any suggestions on how to correct this would be appreciate. </p> <p><strong>Member Model</strong> </p> <pre><code>public partial class Member { NCOWW_DB db = new NCOWW_DB(); public Member() { this.Contacts = new HashSet&lt;Contact&gt;(); this.Utilities = new HashSet&lt;Utility&gt;(); } public int MemberID { get; set; } [Display(Name = "Member Name")] [Required] public string Name { get; set; } [Display(Name = "Member Number")] public string Number { get; set; } [Display(Name = "Mutual Aid Agreement On File")] public bool MutualAid { get; set; } [Display(Name = "Type ID")] public Nullable&lt;int&gt; TypeID { get; set; } [ForeignKey("TypeID")] public virtual UtilityType MemberType { get; set; } [Display(Name = "Water Population")] public Nullable&lt;int&gt; WaterPopulation { get; set; } [Display(Name = "Wastewater Population")] public Nullable&lt;int&gt; WastewaterPopulation { get; set; } private Address _Address = new Address(); public Address Address { get { return _Address; } set { _Address = value; } } private Coordinates _Coordinates = new Coordinates(); public Coordinates Coordinates { get { return _Coordinates; } set { _Coordinates = value; } } [NotMapped] public double Distance { get; set; } public bool Deleted { get; set; } [Display(Name = "Enable Member")] public bool Enabled { get; set; } private DateTime _createdOn = DateTime.UtcNow; public DateTime CreatedOn { get { return _createdOn; } set { _createdOn = value; } } private DateTime _modifiedOn = DateTime.UtcNow; public DateTime ModifiedOn { get { return _modifiedOn; } set { _modifiedOn = value; } } public System.Guid ModifiedBy { get; set; } //public virtual ICollection&lt;Utility&gt; Contacts { get; set; } private ICollection&lt;Contact&gt; _Contacts; public virtual ICollection&lt;Contact&gt; Contacts { get { return (from c in db.Contact where (c.MemberID == MemberID &amp;&amp; c.Deleted == false) select c).OrderBy(c =&gt; c.FirstName).ToList(); } set { _Contacts = value; } } //public virtual ICollection&lt;Utility&gt; Utilities { get; set; } private ICollection&lt;Utility&gt; _Utilities; public virtual ICollection&lt;Utility&gt; Utilities { get { return (from u in db.Utility where (u.MemberID == MemberID &amp;&amp; u.Deleted == false) select u).OrderBy(u =&gt; u.Name).ToList(); } set { _Utilities = value; } } } </code></pre> <p><strong>Utility Model</strong></p> <pre><code> public partial class Utility { NCOWW_DB db = new NCOWW_DB(); public Utility() { this.Contacts = new HashSet&lt;Contact&gt;(); this.Resources = new HashSet&lt;UtilityResource&gt;(); } [Key] public int UtilityID { get; set; } [Display(Name="Member")] [Required] public int MemberID { get; set; } [ForeignKey("MemberID")] public virtual Member Member { get; set; } [ForeignKey("UtilityID")] public virtual ICollection&lt;UtilityResource&gt; Resources { get; set; } [ForeignKey("UtilityID")] private ICollection&lt;Contact&gt; _Contacts; public virtual ICollection&lt;Contact&gt; Contacts { get { return (from c in db.Contact where (c.MemberID == MemberID &amp;&amp; c.Deleted == false) select c).OrderBy(c =&gt; c.FirstName).ToList(); } set { _Contacts = value; } } //public virtual ICollection&lt;Contact&gt; Contacts { get; set; } [Required] public string Name { get; set; } private Address _Address = new Address(); public Address Address { get { return _Address; } set { _Address = value; } } private Coordinates _Coordinates = new Coordinates(); public Coordinates Coordinates { get { return _Coordinates; } set { _Coordinates = value; } } [Display(Name = "Utility Type")] public int? TypeID { get; set; } [ForeignKey("TypeID")] [Display(Name = "Utility Type")] public virtual UtilityType UtilityType { get; set; } [Display(Name = "Region")] public int? RegionID { get; set; } [Display(Name = "County")] public int? CountyID { get; set; } private UtilityInfo _WaterInfo = new UtilityInfo(); [Display(Name="Water Information")] public UtilityInfo WaterInfo { get { return _WaterInfo; } set { _WaterInfo = value; } } private UtilityInfo _WastewaterInfo = new UtilityInfo(); [Display(Name = "Wastewater Information")] public UtilityInfo WastewaterInfo { get { return _WastewaterInfo; } set { _WastewaterInfo = value; } } [NotMapped] public double Distance { get; set; } private bool _enabled = true; public bool Enabled { get { return _enabled; } set { _enabled = value; } } public bool Deleted { get; set; } private DateTime _createdOn = DateTime.UtcNow; public DateTime CreatedOn { get { return _createdOn; } set { _createdOn = value; } } private DateTime _modifiedOn = DateTime.UtcNow; public DateTime ModifiedOn { get { return _modifiedOn; } set { _modifiedOn = value; } } public Guid ModifiedBy { get; set; } } </code></pre> <p><strong>Contact Model</strong></p> <pre><code> public partial class Contact { public Contact() { this.Phones = new HashSet&lt;ContactPhone&gt;(); } [Key] public int ContactID { get; set; } public Nullable&lt;Guid&gt; UserID { get; set; } [Display(Name = "Member")] public int MemberID { get; set; } public Nullable&lt;int&gt; UtilityID { get; set; } public string Username { get; set; } [Display(Name = "First Name")] [Required] public string FirstName { get; set; } [Display(Name = "Last Name")] [Required] public string LastName { get; set; } [NotMapped] public string FullName { get { return FirstName + " " + LastName; } } [NotMapped] public string FullNameLastNameFirst { get { return LastName + ", " + FirstName; } } [Display(Name = "Contact Type")] public string Type { get; set; } [RegularExpression(@"\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*")] [Required] public string Email { get; set; } [ForeignKey("ContactID")] public virtual ICollection&lt;ContactPhone&gt; Phones { get; set; } [NotMapped] [Display(Name = "Grant Website Access")] public bool WebsiteAccess { get; set; } public bool Deleted { get; set; } private DateTime _createdOn = DateTime.UtcNow; public DateTime CreatedOn { get { return _createdOn; } set { _createdOn = value; } } private DateTime _modifiedOn = DateTime.UtcNow; public DateTime ModifiedOn { get { return _modifiedOn; } set { _modifiedOn = value; } } public System.Guid ModifiedBy { get; set; } public virtual Member Member { get; set; } public virtual Utility Utility { get; set; } [NotMapped] public string Password { get; set; } [NotMapped] [Compare("Password")] [Display(Name = "Confirm Password")] public string PasswordConfirm { get; set; } } public partial class ContactPhone { [Key] public int PhoneID { get; set; } public int ContactID { get; set; } public string Number { get; set; } public string Type { get; set; } } </code></pre> <p><strong>Member Edit Controller</strong></p> <pre><code> private NCOWW_DB db = new NCOWW_DB(); //dbContext public ActionResult Edit(Member member) { try { if (ModelState.IsValid) { member.ModifiedBy = CurrentUser; member.ModifiedOn = DateTime.UtcNow; db.Entry(member).State = EntityState.Modified; &lt;--ERROR OCCURS HERE! db.SaveChanges(); //RETURN TO DASHBOARD return RedirectToAction("Index"); } } catch (Exception err) { /*catch error code*/ } return View(member); } </code></pre> <p><strong>UPDATE</strong></p> <p>Based on the answer below, I have modified my code in an attempt to remove the ill-placed <code>NCOWW_DB db = new NCOWW_DB()</code>. However, this does not solve the problem as I am unsure how to pass the <code>dbContext</code> properly. Regardless, this is where the code currently stands:</p> <p><strong>UPDATED MEMBER MODEL</strong></p> <pre><code> ... private ICollection&lt;Contact&gt; _Contacts; public virtual ICollection&lt;Contact&gt; Contacts { get { return MemberFunctions.LoadMemberContacts(MemberID); } set { _Contacts = value; } } private ICollection&lt;Utility&gt; _Utilities; public virtual ICollection&lt;Utility&gt; Utilities { get { return MemberFunctions.LoadMemberUtilities(MemberID); } set { _Utilities = value; } } } public static class MemberFunctions { public static ICollection&lt;Contact&gt; LoadMemberContacts(int memberID) { NCOWW_DB db = new NCOWW_DB(); return (from c in db.Contact where (c.MemberID == memberID &amp;&amp; c.UtilityID == null &amp;&amp; c.Deleted == false) select c).OrderBy(c =&gt; c.FirstName).ToList(); } public static ICollection&lt;Utility&gt; LoadMemberUtilities(int memberID) { NCOWW_DB db = new NCOWW_DB(); return (from u in db.Utility where (u.MemberID == memberID &amp;&amp; u.Deleted == false) select u).OrderBy(u =&gt; u.Name).ToList(); } } </code></pre>
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