When a cell containing a number has a format applied to it in a .xlsx document, a <xf> element is assigned to that cell. These elements are defined in the xl/styles.xml document of a .xlsx workbook. numFmtId is one of the attributes of the <xf> element. There are two general types of numFmtIds which, for purposes of this document, will be referred to as standard and custom.
When a format is applied to a number, the actual value of the number does not change. Instead, a formatCode is applied to the cell which defines how the value contained within the cell should be displayed. The numFmtId is actually a reference to a formatCode.
Excel has many baked-in number formats. The formatCode for these formats are implied rather than explicitly stated in the xl/styles.xml file and are referenced by standard numFmtIds. Custom formats on the other hand can vary from system to system and are therefore explicitly defined in the xl/styles.xml file. formatCodes for custom formats are referenced by custom numFmtIds.
Xlsxir has been designed to capture the majority of both standard and custom formats, however, due to the number of varying types there is a possibility a few could have slipped through. If you receive an error of Unsupported style type: x, that is most likely the issue. The "style type" is simply a numFmtId that is currently not supported by Xlsxir. Any time unsupported style types are identified, please submit an issue on GitHub. If you would like to manually add the style type to your local instance of Xlsxir, only a few simple steps are required as outlined below.
The Xlsxir.ParseStyle module handles the parsing of the xl/styles.xml file. It is designed to determine whether the underlying value of each formatCode is either a number (which includes both integer and float) or a date serial number and return a list of numFmtIds which have been translated to either nil for numbers or 'd' for dates.
To manually update the code for an unsupported style type, locate the Xlsxir.ParseStyle module. The top portion of the module should look like this:
defmodule Xlsxir.ParseStyle do
alias Xlsxir.{Style, Index}
@moduledoc """
Holds the SAX event instructions for parsing style data via `Xlsxir.SaxParser.parse/2`
"""
# the following module attributes hold `numStyleId`s for standard number styles, grouping them between numbers and dates
@num [0,1,2,3,4,9,10,11,12,13,37,38,39,40,44,48,49,59,60,61,62,67,68,69,70]
@date [14,15,16,17,18,19,20,21,22,27,30,36,45,46,47,50,57]
The module attributes @num and @date are lists of standard numFmtIds. Determine whether the underlying value of your unsupported "style type" is a number or a date and then add the "style type" to the appropriate module attribute list.
If you have any trouble with this, please submit an issue.