从列表中删除文件后，自动重命名filname无法正常工作

Question

I am saving file names in database. Before saving I am checking to see if the filename exists in the database already. If it does, I want to append a unique ID after the file name, for example (1) or (2) and so on after the file name.

Everything is working fine, but when I delete a file from the retrieved list and from the database, sometimes a get a duplicate file name. My code is:

var count = dbitems().Count(x.Name == name || x.Name.Contains(name + "("));         
if (count > 0)
{
    name = name + string.Format("({0})", count);
}

Suppose I have saved 4 files with names

(1) File   
(2) File(1)    
(3) File(2)    
(4) File(3)    

And from this list I have deleted File(2). When I try to save a file with the name "File" my output is File(3), but this already exists. The required output should be "File(2)" (as (2) was deleted and this name can be allocated) or "File(4)". I have tried with count + 1 also but this is also creating problem.

In simple words, I want behavior like windows explorer to create new name that automatically assigns a unique suffix.

Answer 1

You have to do it in a loop:

string origName = name;
int version = 0;
while(dbitems().Count(x.Name == name) > 0)         
{
    name = origName  + string.Format("({0})", ++version);
}

This tries name, name(1), name(2), ... until it finds a free "slot". It will also work if

name, name(1), name(5), name(6)

already exist

Answer 2

Thank you all guys for your kind help. I appreciate all of you. Here is what i implement as my solution.

      public string UniqueName(string name, int parentId)
        {
           var files = allFiles.Where(x => x.ParentId == parentId).ToList();               

            var newName = name;
            if (files.Count() > 0)
            {
                for (var i = 1; i <= matches; i++)
                {
                    if (files.Any(x => x.Name == newName 
                        newName = string.Format("{0}({1})", name, i);

                    else
                        return newName 

                }

            }

            return newName 
    }

Answer 3

You're going to need to check each candidate name, so maybe something more like:

int count = 0;
string baseName = name;
while (dbitems().Any(x.Name == name))
{
    count++;
    name = string.Format("{1} ({0})", count, baseName);
}