How to do optional parameters in LINQ?

Here is what I'm trying to do:

(Dc.DET_Cases.Where(c => c.ProductID == pl.ProductID 
                    && oldTOR == false ? c.OldTOR == oldTOR : 
                    && (productLineName.ToInt() == 0 || productLineName.ToInt() == c.ProductLineID)
                    && (productCategory.ToInt() == 0 || productCategory.ToInt() == c.ProductCategoryID)
                    && (issueType.ToInt() == 0 || issueType.ToInt() == c.IssueTypeID)
                    && (issue.ToInt() == 0 || issue.ToInt() ==开发者_运维问答 c.IssueID)
                    )
                    .FirstOrDefault() != null)

This is the line I'm trying to do.

oldTOR == false ? c.OldTOR == oldTOR :

inside a where LINQ statement. If the value is false then compare the value. If not, then ignore it.

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The easiest way to do this is to just set the other option to be true.

Ie: !oldTOR ? c.OldTOR == oldTOR : true

This means that if oldTor is false, then we want to compare OldTor's, otherwise, keep evaluating the rest of the expression.

As an aside, I would split each part of your massive .Where() boolean comparison into individual .Where() statements. This will improve readability and comprehension of your Linq.

    Dc.DET_Cases
        .Where(c => c.ProductID == pl.ProductID)
        .Where(c => !oldTOR ? c.OldTOR == oldTOR :  true)
        .Where(c => productLineName.ToInt() == 0 || productLineName.ToInt() == c.ProductLineID)
        .Where(c => productCategory.ToInt() == 0 || productCategory.ToInt() == c.ProductCategoryID)
        .Where(c => issueType.ToInt() == 0 || issueType.ToInt() == c.IssueTypeID)
        .Where(c => issue.ToInt() == 0 || issue.ToInt() == c.IssueID)
        .FirstOrDefault() != null;

This makes it clear that if oldTor is false then you want to compare, otherwise, pass that statement (true).

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I think you can use the LINQ Dynamic Query Library.

And then create a query as you like.

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The fastest way to do this is by evaluation paths:

oldTOR && (c.OldTor == oldTOR)

Why is this the fastest? Answer: if oldTOR is false then the whole and statement is false, and there is no need to compare the rest of the statement.