如何在SharePoint对象模型中筛选ListItemCollection，排除匹配数据库文件名的项

Hey there! Let's work through this together. You've already fetched all 4 files into your listItems collection using CAML, and now you need to filter out any items where the filename matches what's stored in your database table. Here's a clean, efficient way to get this done:

Step 1: Fetch excluded filenames from your database #

First, you'll want to pull all the filenames you need to exclude into a collection. Using a HashSet<string> is ideal here because it makes lookups super fast—way quicker than a regular List<string> when dealing with even moderately sized datasets.

// Replace this with your actual database call to get excluded filenames
HashSet<string> excludedFileNames = GetExcludedFileNamesFromDatabase();

// Optional: If you need case-insensitive matching (e.g., "File.txt" vs "file.txt"), initialize the HashSet like this:
// HashSet<string> excludedFileNames = new HashSet<string>(GetExcludedFileNamesFromDatabase(), StringComparer.OrdinalIgnoreCase);

Step 2: Filter your ListItemCollection #

Now that you have your excluded filenames, you can filter the listItems collection. We'll use LINQ for this (make sure you have using System.Linq; at the top of your file), but I'll also include a loop-based alternative if you prefer that.

LINQ Approach (Clean & Concise)

// Cast the ListItemCollection to an IEnumerable<ListItem> so we can use LINQ methods
var filteredItems = listItems.Cast<ListItem>()
    .Where(item => !excludedFileNames.Contains(item["FileLeafRef"].ToString()))
    .ToList();

Loop-Based Alternative (For Those Who Prefer Explicit Iteration)

List<ListItem> filteredItems = new List<ListItem>();
foreach (ListItem item in listItems)
{
    // Get the filename from SharePoint (FileLeafRef is the internal field for the filename)
    string fileName = item["FileLeafRef"].ToString();
    
    // Only keep the item if its filename isn't in the excluded list
    if (!excludedFileNames.Contains(fileName))
    {
        filteredItems.Add(item);
    }
}

Full Integrated Code #

Here's how it all fits into your existing code:

CamlQuery camlQuery = new CamlQuery();
// Note: You don't need to escape the angle brackets when using a verbatim string (@)
camlQuery.ViewXml = @"<View Scope='RecursiveAll'> <Query> </Query> </View>";
camlQuery.FolderServerRelativeUrl = folder.ServerRelativeUrl;

ListItemCollection listItems = list.GetItems(camlQuery);
clientContext.Load(listItems);
clientContext.ExecuteQuery();

// Fetch excluded filenames from database
HashSet<string> excludedFileNames = GetExcludedFileNamesFromDatabase();

// Filter the items
var filteredItems = listItems.Cast<ListItem>()
    .Where(item => !excludedFileNames.Contains(item["FileLeafRef"].ToString()))
    .ToList();

Quick Notes #

• FileLeafRef is SharePoint's internal field name for the filename (including extension). If you're using a custom field to store filenames, replace this with the internal name of your custom field.
• Always make sure the filenames from your database match the casing of the SharePoint filenames, or use the case-insensitive HashSet initialization if needed to avoid missing matches.

内容的提问来源于stack exchange，提问作者Neo