如何在 Linq 中进行此查询？

Question

I have a list of paths in a database.

\\apollon\HardDev\01_Elektronik\***
\\apollon\Sales\Kunden\S\***
\\apollon\HardDev\02_Optik\Optik\***_Projekte_Salb\***
\\apollon\Sales\Kunden\O\***\Auftrag 2002_2008-09-09
\\apollon\Sales\Kunden\H\***\Auftrag 4534_2013-07-26
\\apollon\User\***\quickies_2016\BSI_screenshots\Neuer Ordner
\\apollon\Sales\Kunden\G\***\Auftrag 2153_2009-06-24
\\apollon\HardDev\01_Elektronik\***\bestuecker_afem_v12
\\apollon\User\***\quickies_2015\src_***
\\apollon\Sales\Kunden\H\***\4352IO_2013-06-07
etc.

Now I needed a query that gets a path as a parameter and only returns to me the direct subfolder and whether there are subfolders in which.

EXAMPLE:

Function gets the path

\\apollon\User\Walzenbach

and as result I would like to know that the path has the following subfolders

{dir = "\\apollon\User\Walzenbach\docs", subfolderCount = 2}
{dir = "\\apollon\User\Walzenbach\doku", subfolderCount = 0}
{dir = "\\apollon\User\Walzenbach\backup", subfolderCount = 10}

That means the folder docs has 2 subfolders, the folder doku has no subfolders and backup has 10 subfolders.

The SQL would go in that direction. But I am also not sure if this is the best SQL query for it and I also need it in Linq

Thanks in advance for your help

Answer 1

Consider using DirectoryInfo.EnumerateDirectories

string directoryName = "\\apollon\User\Walzenbach"
DirectoryInfo directory = new DirectoryInfo(directoryName);
// TODO: exception if !directory.Exists;

var result = directory.EnumerateDirectories()
    .Select(subDirectory => new
    {
        SubDirectory = subDirectory,       // This is a DirectoryInfo

        // if you prefer the name, instead of the Directory:
        SubDirectoryName = subDirectory.Name,

        // count the number of subfolders of this subfolder:
        SubFolderCount = subFolder.EnumerateDirectories().Count(),
    });

Simple comme bonjour!

Answer 2

Here's a suggestion :

var query=from d in directories
          join sf in directories on d.Path equals sf.ParentPath into grp1
          from sf in grp1.DefaultIfEmpty()
          let result=new {dir=d,sub=sf}
          where reault.dir.Path.StartsWith(path)
          group result by result.dir.Path into grp2
          select new {dir=grp2.Key,subFolderCount=grp2.Count()};

Answer 3

So now I have a SQL that at least reasonably does what I want ... But Linqer can not translate it into Linq

SELECT [Directory], subfolderCount = 
    (SELECT COUNT([Directory])
    FROM [ArgesPerm].[argarm].[dirs]
    WHERE lower([Directory]) LIKE '\\apollon\user\walzenbach\%'
    GROUP BY [Directory])
FROM [ArgesPerm].[argarm].[dirs]
WHERE lower([Directory]) LIKE '\\apollon\user\walzenbach\%'
AND LEN(SUBSTRING([Directory], 3, 10000)) - Len(Replace(SUBSTRING([Directory], 3, 10000), '\', '')) < 3
GROUP BY [Directory]
ORDER BY [Directory]