Excel is the king of spreadsheets and I often find myself in situation where I have to write our Excel files in an application. I'd say that as an application grows the probability of needing Excel import or export approaches 1. Fortunately, there are lots of libraries out there to help with Excel across just about every language. The quality and usefuleness of these libraries varies a lot. In Ruby land there seem to be a few options.
As the name suggests this library deals with Excel spreadsheets. It is able to both read and write them by using Spreadsheet::Excel Library and the ParseExcel Library. However it only supports the older XLS file format. While this is still widely used it is not the default format for Excel 2007 and later. I try to stay clear of the format as much as possible. There have not been any releases of this library in about 18 months but there haven't been any releases of the XLS file format for decades so it doesn't seem like a big deal.
The library can be installed using
gem install spreadsheet
Then you can use it like so
There are some limitations around editing files such as cell formats not updating but for most things it should be fine.
This library works on the more modern XLSX file formats. It is able to read and write files with modifications. However there are some limitations such as being unable to insert images
This library is the community supported version of AXLSX. It is able to generate XLSX files but not read them or modify them. There is rich support for charts, images and other more advanced excel features. The
gem install caxlsx
And then a simple example looks like
Of all the libraries mentioned here the documentation for this one is the best. It is also the most actively maintained. The examples directory https://github.com/caxlsx/caxlsx/tree/master/examples gives a plethora of examples of how to use the library.
This library focuses on being the fastest excel library for ruby. It is actually written in C to speed it up so comes with all the caveats about running native code. Similar to CAXLSX it is only able to read and write files and not modify them.
As you can see here the library really excels at adding consistently shaped rows. You're unlikely to get a complex spreadsheet with headers and footers built using this tooling.