Question

I want to search all XML files which contains a special tag, e.g. ‘field’ within their contents. How can I achieve this with Directory.GetFiles(...) method in C# ?

string[] filePathsFields = Directory.GetFiles(@"E:\Code\", "*.xml", SearchOption.AllDirectories);

Answer 1

Let we have

string path= "E:\\Code";

then

IEnumerable<XDocument> q =
    Directory.EnumerateFiles(path, "*.xml") // iterate thru each XML file into the dir
    .Select(x => XDocument.Load(x)) // load each file into memory
    .Where(d => doc.Descendants("field").Count() > 0); // determine tag existence

or

IEnumerable<XDocument> q = from file in Directory.EnumerateFiles(path, "*.xml")
                           let doc = XDocument.Load(file)
                           where doc.Descendants("field").Count() > 0
                           select doc;

---

Pre .NET 4.0 solution:

Just replace

Directory.EnumerateFiles(dir, "*.xml")

with

Directory.GetFiles(dir, "*.xml", SearchOption.AllDirectories)

---

Select the resulting node itself:

IEnumerable<IEnumerable<XElement>> qq = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
                                        let doc = XDocument.Load(file)
                                        let field = doc.Descendants("field")
                                        let ignore = doc.Descendants("ignore")
                                        where field.Count() > 0 && ignore.Count() == 0
                                        select field;

returns nested IEnumerable<> because each document can contain several resulting nodes.

---

To select only file names:

IEnumerable<string> q = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
                        let doc = XDocument.Load(file)
                        where doc.Descendants("field").Count() > 0
                        select file;

or if you don’t want to load data to appropriate XDocument object:

IEnumerable<string> q = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
                        let data = File.ReadAllText(file)
                        where data.Contains("field")
                        select file;

but the last will return a lot of additional stuff and junk, I guess.

---

File and folder exclusion:

var q = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
        where !new[] { "file1", "file2" }.Contains(file)
        let doc = XDocument.Load(file)
        where doc.Descendants("field").Count() > 0
        select file;

var q = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
        where !new[] { "c:\\foo\\bar", "c:\\blah\\blah" }.Contains(Path.GetDirectoryName(file))
        let doc = XDocument.Load(file)
        where doc.Descendants("field").Count() > 0
        select file;

Attributes count condition:

var q = from file in Directory.GetFiles(path, "*.xml", SearchOption.AllDirectories)
        let doc = XDocument.Load(file)
        from f  in doc.Descendants("field")
        where f.Attributes("id").Count() > 0 && f.Attributes("name").Count() > 0
        select file;