manav inder manav inder - 2 months ago 32
C# Question

ToList().ForEach in Linq

I am new to Linq.

I want to set two values in foreach statement like this

My actual code is this

foreach (Employee emp in employees)
{
foreach(Department dept in emp.Departments)
{
dept.SomeProperty = null;
}
collection.AddRange(emp.Departments);
}


Little refactoring turns the above into this

foreach (Employee emp in employees)
{
emp.Departments.ToList().ForEach(u => u.SomeProperty = null))
collection.AddRange(emp.Departments);
}


But I want something like this

employees.ToList().Foreach(collection.AddRange(emp.Departments),
emp.Departments.ToList().ForEach(u => u.SomeProperty = null))

Answer

You shouldn't use ForEach in that way. Read Lippert's “foreach” vs “ForEach”

If you want to be cruel with yourself (and the world), at least don't create useless List

employees.All(p => {
    collection.AddRange(p.Departments);
    p.Departments.All(u => { u.SomeProperty = null; return true; } );
    return true;
});

Note that the result of the All expression is a bool value that we are discarding (we are using it only because it "cycles" all the elements)

I'll repeat. You shouldn't use ForEach to change objects. LINQ should be used in a "functional" way (you can create new objects but you can't change old objects nor you can create side-effects). And what you are writing is creating so many useless List only to gain two lines of code...