How to work with Conditional Linq Query?

Question

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Conditional Linq Queries

We're working on a Log Viewer. The use will have the option to filter by user, severity, etc. In the Sql days I'd add to the query string, but I want to do it with Linq. How can I conditionally add where-clauses?

Answer 1

Assuming you are working with IEnumerable, like this:

IEnumerable<LogMessage> logs = /* whatever your source is */
if(condition) {
    logs = logs.Where(log => log.Severity == Severity.Error); // or whatever
}

You can also do this multiple times. If your data source is IQueryable use that instead of IEnumerable.