When building Excel import/export functionality in .NET, developers often assume a cell is just a value. In reality, OOXML represents values in multiple ways, and each representation has its own pitfalls. This article examines the common challenges: XML escaping for special characters, UTF-8 handling, inline strings versus shared strings, sparse columns that skip empty cells, rich text formatting, and the Excel date system that stores dates as serial numbers. The author, HueiFeng, walks through a unified read/write pipeline that handles these cases consistently. For example, when exporting, .NET values must be converted into valid OOXML cell XML; when importing, the logical column and text must be recovered from various cell representations. The post is particularly valuable for developers maintaining libraries like Magicodes.IE.IO or integrating with Open XML SDK. It provides a mental model for debugging cell-related issues and designing robust conversion layers. While the article is code-adjacent, the concepts apply broadly to any OOXML-based tooling.
Explore the hidden complexities of OOXML cell handling in .NET: XML escaping, inline strings, sparse columns, rich text, and date serialization. Essential reading for Excel library maintainers.