Excel-Friendly XML Schemas

Several characteristics make an XML schema more amenable to being mapped into Excel. First, an XML schema should have one root element. In our example in this chapter, the root element is Order. If a schema supports more than one root element, you must choose which element will be the root element when adding the XML map to the spreadsheet.

Unsupported XML Schema Constructs

Excel does not support several XML schema constructs. Table 21.1 lists these constructs.

Table 21.1. XML Schema Constructs That Are Not Supported by Excel

Construct	What It Does
<any>	Allows you to include arbitrary elements that are not declared by the schema.
<anyAttribute>	Allows you to include arbitrary attributes that are not declared by the schema.
recursion	A structure that refers to itself recursively.
abstract elements	Allows an element to be declared but never usedalso uses substitution to substitute other elements for the abstract element.
<substitutionGroup>	Allows an element to be substituted for another element.
mixed content	When XML elements are intermixed with non-XML elements. This proves to be very useful for Word XML mapping.

Constructs That Can Be Mapped But Not Exported

There are also several things that can be mapped, but the generated mappings cannot be exported as XML. You have already seen that if an XML mapping is denormalized, it cannot be exported. You also cannot export a list of items containing a second list of items. Choice elements also cannot be exported.

The other general class of issues that prevents exporting is when a mapped element's relationship with another element it is related to cannot be preserved by the mapping. For more information on these types of mapping issues, consult the Excel documentation.

VSTO-Friendly Schemas

VSTO puts some additional requirements on schema mapping if you want to use a schema-mapped spreadsheet with VSTO. First, you need to have a schema mapping that can be exported. Second, all the schema mapping must be within a single worksheet. Although Excel will let you map some elements of the schema to Sheet1 and other elements to Sheet2, VSTO requires that all schema mapping for a given schema be on the same sheet.

How XML Schema Data Types Are Mapped to Excel Cell Formats

As you saw earlier in this book when mapping dates, Excel can automatically pick cell formatting based on the type in the schema. When we dragged a date into Excel, Excel prompted to change the cell formatting. Table 21.2 shows how Excel maps schema types to Excel cell-formatting settings.

Table 21.2. XML Schema Types and Their Corresponding Excel Cell Formatting

XML Type	Excel Formatting
anytype	Text
anyURI	Text
base64Binary	Text
boolean	Boolean
byte	General
date	Date *3/14/2001
dateTime	m/d/yyyy h:mm
decimal	General
double	General
duration	Text
ENTITIES	Text
ENTITY	Text
float	General
gDay	Number, no decimals
gMonth	Number, no decimals
gMonthDay	Custom d-mmm
gYear	Number, no decimals
gYearMonth	Custom mmm-yy
hexBinary	Text
ID	Text
IDREF	Text
IDREFS	Text
int	General
integer	General
language	Text
long	General
Name	Text
NCName	Text
negativeInteger	General
NMTOKEN	Text
NMTOKENS	Text
nonNegativeInteger	General
nonPositiveInteger	General
normalizedString	Text
NOTATION	Text
positiveInteger	General
QName	Text
short	General
string	Text
time	h:mm:ss
token	Text
unsignedByte	General
unsignedInt	General
unsignedLong	General
unsignedShort	General