检查复杂对象上的字符串属性是否包含条件，如果不为null或为空

Question

I am using a Search Class with 3 properties: Machine, Action, Part.
The Search page has 3 textbox controls for user to search on these properties. Is there an efficient way to search on any combination of these properties containing a value?
So a user can potentially search on all 3 properties or any combination of the properties if they are not null or empty.

I am building logic to query database using EF based on the above.

Answer 1

I do such stuff the following way (as an extension method):

public static IQueryable<MyClass> Filter(this IQueryable<MyClass> items, string machineQuery, string actionQuery, string partQuery)
{
    if (!String.IsNullOrWhiteSpace(machineQuery)
        items = items.Where(i => i.Machine.Contains(machineQuery);

    if (!String.IsNullOrWhiteSpace(actionQuery)
        items = items.Where(i => i.Action.Contains(actionQuery);

    if (!String.IsNullOrWhiteSpace(partQuery)
        items = items.Where(i => i.Part.Contains(partQuery);

    return items;
}

This is converted to a DB-side query by EF. You then use it like:

var filteredItems = dbContext.MyClasses.Filter(machineQuery, actionQuery, partQuery);