Object reference exception

Peter Dzuya

11y1.7kVisual Basic .NET

Hi Experts,

I want to create a new customer whose name already exists from a list of contacts.

Once the customer entity has been created, a receivable and possibly a payable account is also created.

But an exception is thrown with a message "Object reference not set to an instance of an object."

on examining further, I find these messages shown below but I don't know how to solve this problem.

'entity.PayableAccount' threw an exception of type 'System.ArgumentNullException'

'entity.ReceivableAccount' threw an exception of type 'System.ArgumentNullException'

below is the UI that enables a new customer to be added from a list on contacts

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Linq;

using System.Threading.Tasks;

using System.Windows.Forms;

using DevExpress.XtraEditors;

using MakGarm.Business;

using MakGarm.Business.Contracts;

using MakGarm.Common.Entities.Core;

using Microsoft.Practices.Unity;

namespace MakGarm.Start.Customers {

public partial class frmAddCustomer : DevExpress.XtraEditors.XtraForm {

private ICustomerService _customerService;

private Customer _customer;

private IContactService _contactService;

//private Contact _contact;

public frmAddCustomer() {

InitializeComponent();

_customerService = UnityConfig.GetContainer().Resolve();

_contactService = UnityConfig.GetContainer().Resolve();

_customer = new Customer() {

Active = true,

Accountclosed = false,

Datecreated = DateTime.Now,

CreditDays = 0,

CreditLimit = 0,

LastEditedDate = DateTime.Now,

CompanyBranchId = CurrentUserInfo.User.CompanyBranch.CompanyId,

CheckerUserId = CurrentUserInfo.User.UserId

};

}

private void frmAddCustomer_Load(object sender, EventArgs e){

customerBindingSource.DataSource = _customer;

ContactBindingSource.DataSource = _contactService.GetAll();

}

private void Acccept_Click(object sender, EventArgs e) {

customerBindingSource.EndEdit();

_customerService.Insert(_customer);

}

the service (_customerService) that the Acccept_Click uses is shown below.

using System;

using System.Collections.Generic;

using System.Collections.ObjectModel;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using MakGarm.Business.Contracts;

using MakGarm.Common.Entities.Core;

using MakGarm.Common.Entities.SubsidiaryLedgerAccounts;

using MakGarm.Common.Enums;

using MakGarm.Persistence.Contracts;

using Uwapi.Utils.Data;

namespace MakGarm.Business.Logic {

public class CustomerService : ICustomerService {

private readonly ICustomerRepository _CustomerRepository;

private readonly ICompanyRepository _companyRepository;

private readonly IFinancialYearService _financialYearService;

private readonly IContactRepository _contactRepository;

private readonly IUnitOfWork _unitOfWork;

public CustomerService(

ICustomerRepository customerRepository,

ICompanyRepository companyRepository,

IFinancialYearService financialYearService,

IContactRepository contactRepository,

IUnitOfWork unitOfWork) {

_CustomerRepository = customerRepository;

_companyRepository = companyRepository;

_financialYearService = financialYearService;

_contactRepository = contactRepository;

_unitOfWork = unitOfWork;

}

public void Insert(Customer entity) {

var company = _companyRepository.GetAll().First();

var contact = entity.Contact ?? _contactRepository.GetById(entity.ContactId);

entity.ContactRelationAccounts = new Collection() {

new PayableContactRelationAccount() {

OpeningDate = _financialYearService.GetDbServerTime(),// AccountBalance = 0,

Active = true,

Type = SubsidiaryLedgerAccountTypeEnum.CustomerReceivable,

BaseAccountType = BaseAccountTypeEnum.Liability,

SubsidiaryLedgerAccountName = string.Format("{0} (Deposit Holding)", contact.ContactName),

Creator = entity.LastEditor,

OpeningBalance = 0,

Description = string.Format("{0} (Deposit Holding)", contact.ContactName),

IsSystemManaged = true,

ControlGeneralLedgerAccountId = company.CreditorsAccountPayableAccountId,},

new ReceivableContactRelationAccount() {

OpeningDate = _financialYearService.GetDbServerTime(),

AccountBalance = 0,

Active = true,

Type = SubsidiaryLedgerAccountTypeEnum.CustomerReceivable,

BaseAccountType = BaseAccountTypeEnum.Asset,

SubsidiaryLedgerAccountName = string.Format("{0} (Receivable)",contact.ContactName),

Creator = entity.LastEditor,

OpeningBalance = 0,

Description = string.Format("{0} (Receivable)", contact.ContactName),

IsSystemManaged = true,

ControlGeneralLedgerAccountId = company.CustomersAccountReceivableAccountId,

};

_CustomerRepository.Add(entity);

_unitOfWork.Commit();

}

public void Update(Customer entity) {

_CustomerRepository.Update(entity);

_unitOfWork.Commit();

}

public Customer GetById(int customerId) {

return _CustomerRepository.GetById(customerId);

}

public void Delete(int customerId) {

var branch = _CustomerRepository.GetById(customerId);

branch.DeletedStatus = true;

_CustomerRepository.Update(branch);

_unitOfWork.Commit();

}

public IEnumerable GetAll() {

return _CustomerRepository.GetMany(s => s.DeletedStatus == false);

}

public IEnumerable GetByCompanyBranchId(int companyBranchId) {

return _CustomerRepository.GetMany(b => b.CompanyBranchId == companyBranchId);

}

and below is the entity used.

using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations;

using System.ComponentModel.DataAnnotations.Schema;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using MakGarm.Common.Entities.Core;

using MakGarm.Common.Entities.Miscellaneous;

using MakGarm.Common.Entities.Documents;

using MakGarm.Common.Entities.SubsidiaryLedgerAccounts;

using MakGarm.Common.Enums;

namespace MakGarm.Common.Entities.Core {

public class Customer : ContactRelation {

#region Primitive Properties

public bool Active { get; set; }

public bool Accountclosed { get; set; }

public DateTime Datecreated { get; set; }

public int CreditDays { get; set; }

public int CreditLimit { get; set; }

[StringLength(255, ErrorMessage = "255 characters max")]

public string Remarks { get; set; }

public DateTime LastEditedDate { get; set; }

#region Foreign Keys

public int CompanyBranchId { get; set; }

public int? CheckerUserId { get; set; }

public int BillingStartFinancialMonthId { get; set; }

#endregion Foreign Keys

#endregion Primitive Properties

#region Navigation Properties

#region Parents

[ForeignKey("BillingStartFinancialMonthId")]

public virtual FinancialMonth BillingStartFinancialMonth { get; set; }

[ForeignKey("CompanyBranchId")]

public virtual CompanyBranch CompanyBranch { get; set; }

[ForeignKey("CheckerUserId")]

public virtual User Checker { get; set; }

#endregion Parents

#region Children

[InverseProperty("Customer")]

public virtual ICollection CustomerInvoices { get; set; }

[InverseProperty("Customer")]

public virtual ICollection CustomerReceipts { get; set; }

[NotMapped]public PayableContactRelationAccount PayableAccount {

get {

return ContactRelationAccounts.OfType().FirstOrDefault();

}

[NotMapped]

public ReceivableContactRelationAccount ReceivableAccount {

get {

return ContactRelationAccounts.OfType().FirstOrDefault();

}

#endregion Children

#endregion Navigation Properties

}

Please assist me. Thanks

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Munesh Sharma11y ago
Accepted answer
From which line this error is coming, generally this error comes due to Null object reference
Peter Dzuya11y ago
Thanks a lot for your efforts. I had a table with a field named "DisplayNumber" which didn't allow null values. I sorted the issue. Tahnks
Peter Dzuya11y ago
Sorry for the delay. I have realized that the exception is thrown in a class called "Initializer" the class is shown here below.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MakGarm.Common.Entities.Core;
using MakGarm.Common.Entities.GeneralLedgerAccounts;
using MakGarm.Common.Entities.Miscellaneous;
using MakGarm.Common.Enums;
namespace MakGarm.Persistence {
///
/// Initalizes the database after creation
///
internal class Initializer {
internal static void Initalize(MakGarmContext context) {
var systemUser = new User() {
Username = "System",
DeletedStatus = false,
NeverAllow = false,
PasswordExpireDays = 10000000,
PasswordHash = "",
NewUser = false,
PasswordLastChangeDate = DateTime.Now,
LastEditedDate = DateTime.Now
};
var company = new Company() {
DeletedStatus = false,
CompanyName = "Sheikh Uniforms Limited",
PinNumber = "PIN",
//LastEditor = systemUser,
FinancialYearStartMonth = 12,
VatNumber = "VAT Number",
VatRate = 16,
LastEditedDate = DateTime.Now
};
var companyBranch1 = new CompanyBranch() {
Company = company,
DeletedStatus = false,
CompanyBranchName = "Main Office",
LastEditedDate = DateTime.Now,
//LastEditor = systemUser,
Floor = "Ground",
PhysicalAddress = "Moi Avenue Mombasa",
Town = "Mombasa",
PostalAddress = "P. O. Box"
};
var companyBranch2 = new CompanyBranch() {
Company = company,
DeletedStatus = false,
CompanyBranchName = "Railway Station",
LastEditedDate = DateTime.Now,
// LastEditor = systemUser,
Floor = "Ground",
PhysicalAddress = "Mombasa",
Town = "Mombasa",
PostalAddress = "P. O. Box"
};
systemUser.CompanyBranch = companyBranch1;
context.DocumentTypes.Add(new DocumentType() { DocumentTypeName = "Funds Transfer", DisplayNumberPrefix = "FUT", Type = DocumentTypeEnum.FundsTransfer });
context.DocumentTypes.Add(new DocumentType() { DocumentTypeName = "Customer Invoice", DisplayNumberPrefix = "TNI", Type = DocumentTypeEnum.CustomerInvoice });
context.DocumentTypes.Add(new DocumentType() { DocumentTypeName = "Customer Receipt", DisplayNumberPrefix = "TNR", Type = DocumentTypeEnum.CustomerReceipt });
context.DocumentTypes.Add(new DocumentType() { DocumentTypeName = "Journal Entry", DisplayNumberPrefix = "JRE", Type = DocumentTypeEnum.JournalEntry });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Accounts Payable Account", Description = "Accounts Payable Account (Control)", DisplayNumberPrefix = "AP", Type = GeneralLedgerAccountTypeEnum.AccountsPayableAccount, BaseAccountType = BaseAccountTypeEnum.Liability, IsControlAccount = true });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Accounts Receivable Account", Description = "Accounts Receivable Account (Control)", DisplayNumberPrefix = "AR", Type = GeneralLedgerAccountTypeEnum.AccountsReceivableAccount, BaseAccountType = BaseAccountTypeEnum.Asset, IsControlAccount = true });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Bank Accounts Control Account", Description = "Bank Accounts Control Account", DisplayNumberPrefix = "BA", Type = GeneralLedgerAccountTypeEnum.BankAccountsControlAccount, BaseAccountType = BaseAccountTypeEnum.Asset, IsControlAccount = true });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Cash Control Account", Description = "Cash Control Account", DisplayNumberPrefix = "CC", Type = GeneralLedgerAccountTypeEnum.CashControlAccount, BaseAccountType = BaseAccountTypeEnum.Asset, IsControlAccount = true });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Equity Account", Description = "Equity (Owners Capital) Account", DisplayNumberPrefix = "EQ", Type = GeneralLedgerAccountTypeEnum.EquityAccount, BaseAccountType = BaseAccountTypeEnum.Equity, IsControlAccount = false });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Expenses Account", Description = "Expenses Account", DisplayNumberPrefix = "EX", Type = GeneralLedgerAccountTypeEnum.ExpensesAccount, BaseAccountType = BaseAccountTypeEnum.Expenses, IsControlAccount = false });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Income Account", Description = "Income Account", DisplayNumberPrefix = "IN", Type = GeneralLedgerAccountTypeEnum.IncomeAccount, BaseAccountType = BaseAccountTypeEnum.Income, IsControlAccount = false });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Other Asset Account", Description = "Other Asset Account", DisplayNumberPrefix = "OA", Type = GeneralLedgerAccountTypeEnum.OtherAssetAccount, BaseAccountType = BaseAccountTypeEnum.Asset, IsControlAccount = false });
context.GeneralLedgerAccountTypes.Add(new GeneralLedgerAccountType() { GeneralLedgerAccountTypeName = "Other Liability Account", Description = "Other Liability Account", DisplayNumberPrefix = "OL", Type = GeneralLedgerAccountTypeEnum.OtherLiabilityAccount, BaseAccountType = BaseAccountTypeEnum.Liability, IsControlAccount = false });
context.SubsidiaryAccountTypes.Add(new SubsidiaryLedgerAccountType() { SubsidiaryLedgerAccountTypeName = "Bank", DisplayNumberPrefix = "BNK", Type = SubsidiaryLedgerAccountTypeEnum.Bank });
context.SubsidiaryAccountTypes.Add(new SubsidiaryLedgerAccountType() { SubsidiaryLedgerAccountTypeName = "Cashier", DisplayNumberPrefix = "CAS", Type = SubsidiaryLedgerAccountTypeEnum.Cashier });
context.SubsidiaryAccountTypes.Add(new SubsidiaryLedgerAccountType() { SubsidiaryLedgerAccountTypeName = "Supplier Payable", DisplayNumberPrefix = "SUP", Type = SubsidiaryLedgerAccountTypeEnum.SupplierPayable });
context.SubsidiaryAccountTypes.Add(new SubsidiaryLedgerAccountType() { SubsidiaryLedgerAccountTypeName = "Customer Payable", DisplayNumberPrefix = "TPY", Type = SubsidiaryLedgerAccountTypeEnum.CustomerPayable });
context.SubsidiaryAccountTypes.Add(new SubsidiaryLedgerAccountType() { SubsidiaryLedgerAccountTypeName = "Customer Receivable", DisplayNumberPrefix = "TRC", Type = SubsidiaryLedgerAccountTypeEnum.CustomerReceivable });
var customerAccountReceivable = new AccountsReceivableAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "Customers' Accounts Receivable",
Type = GeneralLedgerAccountTypeEnum.AccountsReceivableAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Asset Control account to keep track of the monies owed by customers.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var creditorsAccountPayable = new AccountsPayableAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "creditors' Accounts Payable",
Type = GeneralLedgerAccountTypeEnum.AccountsPayableAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Liability Control account to keep track of the monies owed to creditors.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var vatOnSalesHolding = new OtherLiabilityGeneralLedgerAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "VAT on Sales - Holding",
Type = GeneralLedgerAccountTypeEnum.OtherLiabilityAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Liability account to keep track of VAT on sales that has been invoiced but not received.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var vatOnSales = new OtherLiabilityGeneralLedgerAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "VAT on Sales",
Type = GeneralLedgerAccountTypeEnum.OtherLiabilityAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Liability account to keep track of VAT on sales that has already been received.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var cashiersControl = new CashGeneralLedgerAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "Cashiers' Control Account",
Type = GeneralLedgerAccountTypeEnum.CashControlAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Asset Control account to keep track of cash in cashiers' accounts.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var bankAccountsControl = new BankAccountsControlAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "Bank Accounts Control Account",
Type = GeneralLedgerAccountTypeEnum.BankAccountsControlAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Asset Control account to keep track of monies in bank accounts.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
var suppliersPayable = new AccountsPayableAccount() {
AccountBalance = 0,
GeneralLedgerAccountName = "Suppliers’ Accounts Payable Account",
Type = GeneralLedgerAccountTypeEnum.AccountsPayableAccount,
Active = true,
IsSystemManaged = true,
Creator = systemUser,
Description = "A Current Liability Control account to keep track of fees owed to Suppliers.",
DisplayNumber = "10001",
OpeningBalance = 0,
OpeningDate = DateTime.UtcNow.AddHours(3)
};
context.Companies.Add(company);
context.CompanyBranches.AddRange(new List() { companyBranch1, companyBranch2 });
//context.GeneralLedgerAccounts.AddRange(new List() {
// customerAccountReceivable,
// creditorsAccountPayable,
// vatOnSalesHolding,
// vatOnSales,
// cashiersControl,
// bankAccountsControl,
// suppliersPayable
//});
var standardVat = new VatCode() {
Description = "Standard VAT",
Percentage = 16M,
ShortName = "S",
VatCodeName = "Standard VAT"
};
var zeroRated = new VatCode() {
Description = "Zero Rated",
Percentage = 0M,
ShortName = "Z",
VatCodeName = "Zero Rated"
};
var exempt = new VatCode() {
Description = "Exempted",
Percentage = 0M,
ShortName = "E",
VatCodeName = "Exempted"
};
var notRegistered = new VatCode() {
Description = "Not Registered",
Percentage = 0M,
ShortName = "N",
VatCodeName = "Not Registered"
};
var unknown = new VatCode() {
Description = "Unknown",
Percentage = 0M,
ShortName = "U",
VatCodeName = "Unknown"
};
context.VatCodes.AddRange(new List() { standardVat, zeroRated, exempt, notRegistered, unknown });
context.Items.Add(new CustomerItem() {
AutoAddInNewPropertyUnit = true,
Description = "Service",
Discontinued = false,
ItemName = "Rent",
//SplittableWith = ContactRelationType.Landlord,
VatCode = standardVat
});
context.SaveChanges();
company.BankAccountsControlAccountId = bankAccountsControl.GeneralLedgerAccountId;
company.CashiersControlAccountId = cashiersControl.GeneralLedgerAccountId;
company.CustomersAccountReceivableAccountId = customerAccountReceivable.GeneralLedgerAccountId;
company.VatOnSalesAccountId = vatOnSales.GeneralLedgerAccountId;
company.VatOnSalesHoldingAccountId = vatOnSalesHolding.GeneralLedgerAccountId;
company.CreditorsAccountPayableAccountId = creditorsAccountPayable.GeneralLedgerAccountId;
company.SystemUserId = systemUser.UserId;
company.LastEditor = systemUser;
companyBranch1.LastEditor = systemUser;
companyBranch2.LastEditor = systemUser;
context.SaveChanges();
}
}
}
but I suspect the "context.Companies.Add(company)" is where the issue is. Thanks
11y ago
Have you created new instance of PayableAccount? if not create new instance of PayableAccount