Using CSOM to Retrieve Files

Oct 13, 2025 by wbrum.org 50 views

As a SharePoint developer, you may encounter situations where a poorly designed architecture leads to folder limitations, causing issues with file storage and management. In this article, we will explore how to use the Client-Side Object Model (CSOM) to retrieve all files from a problematic SharePoint website and migrate them to a new website or subsites.

Understanding the Problem

When a large number of files are stored in multiple lists, it can lead to folder over-limit issues, making it difficult to manage and maintain the SharePoint site. In your case, the previous developer placed 16,000 files in 2,000 different lists, causing the folder limitations. This can result in performance issues, errors, and a poor user experience.

Using CSOM to Retrieve Files

To overcome this issue, you can use the CSOM to retrieve all files from the problematic website. CSOM is a .NET API that allows you to interact with SharePoint from client-side applications. It provides a robust and efficient way to perform operations on SharePoint data.

Here's an example of how to use CSOM to retrieve all files from a SharePoint website:

using Microsoft.SharePoint.Client;
// Create a new instance of the ClientContext class
ClientContext ctx = new ClientContext("https://your-sharepoint-site.sharepoint.com");
// Get the web object
Web web = ctx.Web;
// Get the files collection
FileCollection files = web.GetFolderByServer("/").Files;
// Load the files collection
ctx.Load(files);
// Execute the query
ctx.ExecuteQuery();
// Iterate through the files collection
foreach (File file in files)
{
// Process the file
Console.WriteLine(file.Name);
}

This code retrieves all files from the root folder of the SharePoint website. You can modify the code to retrieve files from specific lists or folders by using the GetFolderByServer method.

Migrating Files to a New Website/Subsites

Once you have retrieved all files from the problematic website, you can migrate them to a new website or subsites using CSOM. This involves creating a new folder structure and copying the files to the new location.

Here's an example of how to migrate files to a new website:

using Microsoft.SharePoint.Client;
// Create a new instance of the ClientContext class
ClientContext ctx = new ClientContext("https://your-new-sharepoint-site.sharepoint.com");
// Get the web object
Web web = ctx.Web;
// Create a new folder
Folder folder = web.GetFolderByServer("/NewFolder");
// Create a new file
File file = folder.Files.Add(new FileCreationInformation
{
Content = "Hello World!",
Overwrite = true,
FileName = "example.txt"
});
// Save the file
file.Save();
// Execute the query
ctx.ExecuteQuery();
// Iterate through the files collection
foreach (File file in files)
{
// Copy the file to the new location
File copyFile = folder.Files.Add(new FileCreationInformation
{
Content = file.Content,
Overwrite = true,
FileName = file.Name
});
// Save the copy file
copyFile.Save();

}

This code creates a new folder and file in the new SharePoint website, and then copies the files from the old website to the new location.

Best Practices for Migrating Files

When migrating files from a problematic website to a new website or subsites, it's essential to follow best practices to ensure a smooth and successful migration. Here are some tips to keep in mind:

Backup your data: Before migrating files, make sure to backup your data to prevent any loss of information.
Test your migration: Test your migration process on a small scale before migrating all files to ensure that everything works as expected.
Use a staging environment: Use a staging environment to test and validate your migration process before deploying it to production.
Monitor performance: Monitor performance during the migration process to ensure that it doesn't impact the user experience.
Document your process: Document your migration process to ensure that it can be repeated in the future.

Conclusion

In this article, we explored how to use CSOM to retrieve all files from a problematic SharePoint website and migrate them to a new website or subsites. By following the best practices outlined in this article, you can ensure a smooth and successful migration of your files. Remember to always backup your data, test your migration process, and monitor performance during the migration process.

Additional Resources

For more information on using CSOM to interact with SharePoint, refer to the following resources:

As a SharePoint developer, you may have questions about using the Client-Side Object Model (CSOM) to interact with SharePoint. In this article, we will address some of the most frequently asked questions about CSOM.

Q: What is CSOM?

A: CSOM is a .NET API that allows you to interact with SharePoint from client-side applications. It provides a robust and efficient way to perform operations on SharePoint data.

Q: What are the benefits of using CSOM?

A: The benefits of using CSOM include:

Improved performance: CSOM is a client-side API, which means that it can perform operations on SharePoint data without requiring a round trip to the server.
Increased flexibility: CSOM allows you to interact with SharePoint data in a more flexible and dynamic way than traditional server-side APIs.
Better scalability: CSOM is designed to handle large volumes of data and can scale to meet the needs of your application.

Q: What are the limitations of CSOM?

A: The limitations of CSOM include:

Security: CSOM requires authentication and authorization to access SharePoint data, which can be a challenge in some environments.
Complexity: CSOM can be complex to use, especially for developers who are new to SharePoint development.
Versioning: CSOM is version-dependent, which means that you need to ensure that your application is compatible with the version of SharePoint that you are using.

Q: How do I get started with CSOM?

A: To get started with CSOM, you will need to:

Install the CSOM NuGet package: You can install the CSOM NuGet package from the NuGet package manager.
Create a new instance of the ClientContext class: You will need to create a new instance of the ClientContext class to interact with SharePoint data.
Load the SharePoint data: You will need to load the SharePoint data into your application using the ClientContext class.

Q: What are some common CSOM operations?

A: Some common CSOM operations include:

Creating a new list: You can create a new list using the ClientContext class.
Adding a new item to a list: You can add a new item to a list using the ClientContext class.
Updating an existing item: You can update an existing item using the ClientContext class.
Deleting an item: You can delete an item using the ClientContext class.

Q: How do I handle errors in CSOM?

A: To handle errors in CSOM, you can use the following techniques:

Try-catch blocks: You can use try-catch blocks to catch and handle exceptions that occur during CSOM operations.
Error handling: You can use error handling techniques such as logging and notification to handle errors that occur during CSOM operations.

Q: What are some best practices for using CSOM?

A: Some best practices for using CSOM include:

Use try-catch blocks: You should use try-catch blocks to catch and handle exceptions that occur during CSOM operations.
Use error handling: You should use error handling techniques such as logging and notification to handle errors that occur during CSOM operations.
Test your application: You should test your application thoroughly to ensure that it is working correctly with CSOM.

Q: What are some common CSOM pitfalls to avoid?

A: Some common CSOM pitfalls to avoid include:

Not handling errors: You should always handle errors that occur during CSOM operations.
Not testing your application: You should always test your application thoroughly to ensure that it is working correctly with CSOM.
Not following best practices: You should always follow best practices for using CSOM to ensure that your application is working correctly and efficiently.

Conclusion

In this article, we have addressed some of the most frequently asked questions about CSOM. We have covered topics such as the benefits and limitations of CSOM, how to get started with CSOM, common CSOM operations, and best practices for using CSOM. By following the guidance in this article, you can ensure that your application is working correctly and efficiently with CSOM.