How to express .Any(y => y.Name == "val")); within an expression tree?

Question

I'm trying to create a DbSet LINQ filter. I'm using expressions so that I can reduce the number of lines of code caused by unique combinations of filter options and filter properties.

I was able to apply this easily for properties of the object in the DbSest (Working Code pasted bellow). But I hit a road block when I was trying to express. dbSet.Where(x => x.listProp.Any(y => y.Name == "val")); I don't know how to express .Any(...) while building an expression tree.

Currently I'm trying to follow the solution in the post but I'm getting the following issue when I get to var anyCall = ... : System.InvalidOperationException: 'No generic method 'Any' on type 'System.Linq.Queryable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic. '

This is what I currently have.

private IQueryable<dbo.Transaction> _FilterTransactionPartyType(ParameterExpression param, IQueryable<Transaction> query, string transactionPartyType)
{

    MemberExpression expM2M = Expression.PropertyOrField(param, "Parties");

    Type tM2M = typeof(M2M_Transactions_Party);
    ParameterExpression paramM2m = Expression.Parameter(tM2M, "m2m");

    //Any(m2m => m2m.Party.Name == "dd" && m2m.PartyType.Name = "dd")
    System.Reflection.PropertyInfo piParty = tM2M.GetProperty("Party");
    System.Reflection.PropertyInfo piPartyName = piParty.PropertyType.GetProperty("Name");
    System.Reflection.PropertyInfo piPartyType = tM2M.GetProperty("TransactionPartyType");
    System.Reflection.PropertyInfo piPartyTypeName = piPartyType.PropertyType.GetProperty("Name");

    MemberExpression expPartyType = Expression.Property(paramM2m, piPartyType);
    MemberExpression expPartyTypeName = Expression.Property(expPartyType, piPartyTypeName);

    ConstantExpression expPartyTypeValue = Expression.Constant(transactionPartyType, typeof(string));
    BinaryExpression isPartyTransactionType = Expression.Equal(expPartyTypeName, expPartyTypeValue);

    MemberExpression expParties = Expression.Property(paramM2m, piParty);
    MemberExpression expParty = Expression.Property(expParties, piPartyName);

    BinaryExpression isParty = _Filter(expParty);

    BinaryExpression isPartyAndType = Expression.AndAlso(isParty, isPartyTransactionType);
    Expression<Func<M2M_Transactions_Party, bool>> internalLambda = Expression.Lambda<Func<M2M_Transactions_Party, bool>>(isPartyAndType, paramM2m);


    // book.properties.Any(bookProperty => bookProperty.type.key == "lingerie" && bookProperty.value == "1")
    var anyCall = Expression.Call(
        typeof(Queryable), "Any", new[] { tM2M },
        expM2M, internalLambda
    );
    // book => book.properties.Any(...)
    var lambda = Expression.Lambda<Func<Transaction, bool>>(anyCall, param);

    return query.Where(lambda);

}

score 0 · Accepted Answer · edited Oct 09 '21 at 19:44

I found out what my issue was.

There was one issue where I had used typeof(Queryable) instead of typeof(Enumerable) and another issue I identified for anyone looking at my method above is that I was passing IQueryable when I should of been just returning Expression<Func<Transaction, bool> and concatenating these after using this post (combining-two-expressions-expressionfunct-bool)

Here is my current method

private Expression<Func<Transaction, bool>> _FilterTransactionPartyType(ParameterExpression param, string transactionPartyType)
{
    MemberExpression expM2M = Expression.PropertyOrField(param, "Parties");

    Type tM2M = typeof(M2M_Transactions_Party);
    ParameterExpression paramM2m = Expression.Parameter(tM2M, "m2m");

    System.Reflection.PropertyInfo piParty = tM2M.GetProperty("Party");
    System.Reflection.PropertyInfo piPartyName = piParty.PropertyType.GetProperty("Name");
    System.Reflection.PropertyInfo piPartyType = tM2M.GetProperty("TransactionPartyType");
    System.Reflection.PropertyInfo piPartyTypeName = piPartyType.PropertyType.GetProperty("Name");

    MemberExpression expPartyType = Expression.Property(paramM2m, piPartyType);
    MemberExpression expPartyTypeName = Expression.Property(expPartyType, piPartyTypeName);

    ConstantExpression expPartyTypeValue = Expression.Constant(transactionPartyType, typeof(string));
    BinaryExpression isPartyTransactionType = Expression.Equal(expPartyTypeName, expPartyTypeValue);

    MemberExpression expParties = Expression.Property(paramM2m, piParty);
    MemberExpression expParty = Expression.Property(expParties, piPartyName);

    BinaryExpression isParty = _Filter(expParty);

    BinaryExpression isPartyAndType = Expression.AndAlso(isParty, isPartyTransactionType);
    Expression<Func<M2M_Transactions_Party, bool>> internalLambda = Expression.Lambda<Func<M2M_Transactions_Party, bool>>(isPartyAndType, paramM2m);

    MethodCallExpression anyCall = Expression.Call(
        typeof(Enumerable), "Any", new[] { tM2M },
        expM2M, internalLambda
    );

    Expression<Func<Transaction, bool>> lambda = Expression.Lambda<Func<Transaction, bool>>(anyCall, param);

    return lambda;
}

How to express .Any(y => y.Name == "val")); within an expression tree?

1 Answers1