Hello, I'm having troubles with the Except() method.
Instead returning the difference, it returns the original set.
I've tried by implementing the IEquatable and IEqualityComparer in the Account.
I've also tried creating a seperate IEqualityComparer class for Account.
When the Except() method is called from main, it doesn't seem to call my custom Equals() method, but when I tried Count(), it did call the custom GetHashCode() method!
I'm sure I made a trivial mistake somewhere and I hope a fresh pair of eyes can help me.
main:
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IEnumerable<Account> everyPartnerID =
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from partner in dataContext.Partners
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select new Account { IDPartner = partner.ID, Name = partner.Name };
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-
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IEnumerable<Account> hasAccountPartnerID =
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from partner in dataContext.Partners
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from account in dataContext.Accounts
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where
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!partner.ID.Equals(Guid.Empty) &&
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account.IDPartner.Equals(partner.ID) &&
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account.Username.Equals("Special")
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select new Account { IDPartner = partner.ID, Name = partner.Name };
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IEnumerable<Account> noAccountPartnerID =
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everyPartnerID.Except(
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hasAccountPartnerID,
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new LambdaComparer<Account>((x, y) => x.IDPartner.Equals(y.IDPartner)));
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Account:
- public class Account : IEquatable<Account>
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{
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public Guid IDPartner{ get; set; }
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public string Name{ get; set; }
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/* #region IEquatable<Account> Members
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public bool Equals(Account other)
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{
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return this.IDPartner.Equals(other.IDPartner);
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}
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#endregion*/
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}
LambdaComparer:
- public class LambdaComparer<T> : IEqualityComparer<T>
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{
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private readonly Func<T, T, bool> _lambdaComparer;
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private readonly Func<T, int> _lambdaHash;
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public LambdaComparer(Func<T, T, bool> lambdaComparer) :
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this(lambdaComparer, o => o.GetHashCode())
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{
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}
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public LambdaComparer(Func<T, T, bool> lambdaComparer, Func<T, int> lambdaHash)
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{
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if (lambdaComparer == null)
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throw new ArgumentNullException("lambdaComparer");
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if (lambdaHash == null)
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throw new ArgumentNullException("lambdaHash");
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_lambdaComparer = lambdaComparer;
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_lambdaHash = lambdaHash;
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}
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public bool Equals(T x, T y)
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{
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return _lambdaComparer(x, y);
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}
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public int GetHashCode(T obj)
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{
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return _lambdaHash(obj);
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}
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}
