I was playing around with LINQPad today and wrote this C# code to export all attachments from CRM. You can customise the query to export only certain attachments if required. You could also modify the code to gather the output location from the user, instead of asking them to choose between “My Documents” or “Desktop”. This could also be potentially written as an XrmToolBox tool.

I executed the code in LINQPad v5.26 and Dynamics CRM 2016 OnPremise 8.1 environment. I tried to retrieve the attachment using LINQ, but decided to use normal QueryByAttribute with paging for performance reasons.

Util.RawHtml("
<h4>Choose an output path</h4>
").Dump();
var folders = new List<Environment.SpecialFolder> { Environment.SpecialFolder.Desktop, Environment.SpecialFolder.MyDocuments };
folders.ForEach(x => new Hyperlinq(() => DumpFiles(Environment.GetFolderPath(x)), x.ToString()).Dump());

void DumpFiles(string selectedFolder)
{
	Util.ClearResults();
	new Hyperlinq(selectedFolder).Dump("Chosen output path");
	var progress = new Util.ProgressBar("Writing files: ").Dump();
	progress.HideWhenCompleted = true;
	var retrieveQuery = new QueryByAttribute("annotation")
	{
		ColumnSet = new ColumnSet("documentbody","filename"),
		PageInfo = new PagingInfo{ Count = 500, PageNumber = 1 }
	};
	retrieveQuery.AddAttributeValue("isdocument", true);
	var resultsDc = new DumpContainer().Dump($"Results");
	EntityCollection results;
	int totalRecordCount = 0;
	do
	{
		results = ((RetrieveMultipleResponse)this.Execute(new RetrieveMultipleRequest { Query = retrieveQuery })).EntityCollection;
		var files = results.Entities.Cast<Annotation>();
		totalRecordCount += results.Entities.Count;
		resultsDc.Content = $"Completed Page {retrieveQuery.PageInfo.PageNumber}, Files: {totalRecordCount}";
		int fileNumber = 0;
		foreach (var f in files)
		{
			fileNumber++;
			var fileContent = Convert.FromBase64String(f.DocumentBody);
			File.WriteAllBytes(Path.Combine(selectedFolder, f.FileName), fileContent);
			progress.Caption = $"Page {retrieveQuery.PageInfo.PageNumber} - Writing files: {fileNumber}/{retrieveQuery.PageInfo.Count}";
			progress.Percent = fileNumber * 100 / retrieveQuery.PageInfo.Count;
		}
		retrieveQuery.PageInfo.PageNumber++;
		retrieveQuery.PageInfo.PagingCookie = results.PagingCookie;
	} while (results.MoreRecords);
	resultsDc.Content = $"{totalRecordCount} files saved.";
}