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POObject reference not set to an instance of an object while Adding Parameter
 

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  1. POObject reference not set to an instance of an object while Adding Parameter
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    <p>I want to update some information when a <code>save</code> button is clicked.</p> <p>I got an error </p> <blockquote> <p>On : command.Parameters.Add("@doctorID", SqlDbType.Int).Value = resident.Doctor.DoctorID; Saying: Object reference not set to an instance of an object.</p> </blockquote> <p>Im guessing I need to create some kind of object?</p> <p><strong>Button code:</strong> </p> <pre><code> private void btnSave_Click(object sender, RoutedEventArgs e) { Resident hello = new Resident(); hello.Doctor = new Doctor(); Resident residentID; txtAdditionalInformation.Text = hello.addtionalInformation; txtForename.Text = hello.FirstName; txtSurname.Text = hello.Surname; txtTitle.Text = hello.Title; ResidentData.Update(hello); } </code></pre> <p><strong>update code (ResidentData Class):</strong> </p> <pre><code> public static void Update(Resident resident, SqlConnection connection, SqlTransaction transaction) { StringBuilder sqlString = new StringBuilder(); SqlCommand command; sqlString.Append("UPDATE [Resident] SET "); sqlString.Append("title = @title, "); sqlString.Append("firstName = @firstName, "); sqlString.Append("surname = @surname, "); sqlString.Append("dateOfBirth = @dateOfBirth, "); sqlString.Append("photo = @photo, "); sqlString.Append("doctorID = @doctorID, "); sqlString.Append("roomID = @roomID, "); sqlString.Append("allergies = @allergies, "); sqlString.Append("additionalInformation = @additionalInformation "); sqlString.Append("WHERE residentID = @residentID "); command = new SqlCommand(sqlString.ToString(), connection); if ((transaction != null)) command.Transaction = transaction; command.Parameters.Add("@residentID", SqlDbType.Int).Value = resident.ResidentID; command.Parameters.Add("@title", SqlDbType.VarChar, 50).Value = Helper.GetValue(resident.Title); command.Parameters.Add("@firstName", SqlDbType.VarChar, 100).Value = Helper.GetValue(resident.FirstName); command.Parameters.Add("@surname", SqlDbType.VarChar, 100).Value = Helper.GetValue(resident.Surname); command.Parameters.Add("@dateOfBirth", SqlDbType.DateTime).Value = Helper.GetValue(resident.DateOfBirth); command.Parameters.Add("@photo", SqlDbType.Image, 2147483647).Value = Helper.GetValue(resident.Photo); command.Parameters.Add("@doctorID", SqlDbType.Int).Value = resident.Doctor.DoctorID; command.Parameters.Add("@roomID", SqlDbType.Int).Value = resident.Room.RoomID; command.Parameters.Add("@allergies", SqlDbType.NText).Value = resident.Allergies; command.Parameters.Add("@additionalInformation", SqlDbType.NText).Value = resident.addtionalInformation; int rowsAffected = command.ExecuteNonQuery(); if (!(rowsAffected == 1)) { throw new Exception("An error has occurred while updating Resident details."); } } </code></pre> <p>*<em>Residence Class:</em></p> <pre><code> { public class Resident { private int residentID; private string title; private string firstName; private string surname; private string searchText; private System.DateTime dateOfBirth; private byte[] photo; private Room room; private Doctor doctor; private string nhs; private string residentBarcode; private string allergies; private string additionalInformation; public Resident() : base() { } public Resident(int newResidentID, string newTitle, string newFirstName, string newSurname, string newSearchText, System.DateTime newDateOfBirth, byte[] newPhoto, Room newRoom, Doctor newDoctor, string newNhs, string newResidentBarcode, string newAllergies, string newAdditionalInformation) : base() { residentID = newResidentID; title = newTitle; firstName = newFirstName; surname = newSurname; searchText = newSearchText; dateOfBirth = newDateOfBirth; photo = newPhoto; room= newRoom; doctor = newDoctor; nhs = newNhs; residentBarcode = newResidentBarcode; allergies = newAllergies; additionalInformation = newAdditionalInformation; } public int ResidentID { get { return residentID; } set { residentID = value; } } public string Title { get { return title; } set { title = value; } } public string FirstName { get { return firstName; } set { firstName = value; } } public string Surname { get { return surname; } set { surname = value; } } public string SearchText { get { return searchText; } set { searchText = value; } } public System.DateTime DateOfBirth { get { return dateOfBirth; } set { dateOfBirth = value; } } public byte[] Photo { get { return photo; } set { photo = value; } } public Room Room { get { return room; } set { room = value; } } public Doctor Doctor { get { return doctor; } set { doctor = value; } } public string NHS { get { return nhs; } set { nhs = value; } } public string ResidentBarcode { get { return residentBarcode; } set { residentBarcode = value; } } public string Allergies { get { return allergies; } set { allergies = value; } } public string addtionalInformation{ get { return additionalInformation; } set { additionalInformation = value; } } } </code></pre> <p>}</p>
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    1. This table or related slice is empty.
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    1. USuser2122032
    1. USuser2122032
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
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    2. PO
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    1. This table or related slice is empty.
    1. COShow your resident class
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      1. POObject reference not set to an instance of an object while Adding Parameter
      1. USRajeev Kumar
    2. COMy guess (and it's an educated one) is that `resident.Doctor` is null - you can't access `DoctorID` if `Doctor` is a null value... hence the null ref exception
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      1. POObject reference not set to an instance of an object while Adding Parameter
      1. USCharleh
    3. COCan you verify that in `resident.Doctor.DoctorID`, neither resident or Doctor is null?
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      1. POObject reference not set to an instance of an object while Adding Parameter
      1. USAnton
 

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