Attributes of block variables

Block variable attributes provide more information about block variables.

The following is a list of block variable attributes.

Block variable attribute Description
._cols Returns a list of column names.
._column.[COLUMN] Returns a package of metadata for the specified column.
._data The entire result of the query as a table value.
._defined Is the variable or component defined? @foo._defined.
._is_empty True if @variable is empty or undefined.
._length Returns the length of a list.
@varlength = @foo._length
In the example above, the block variable @foo._length returns the length of the list @foo.
._members When applied to a package, yields a list of the package's member names.
._or_empty Returns "" if the variable is undefined, otherwise returns the variable value.
._pretty A string representing a human-readable form of @variable (where possible).
._rows Returns the number of rows.
._tag Returns the name of an XML tag.
@myvar = <foo bar="5"><baz/></foo>
In the example above, the block variable @myvar._tag returns the string foo.
._tohtml HTML-escaped version of the string form of @variable.
._tojson JSON-encoded version of @variable (where possible).
._tostring The string form of @variable.
._type The variable type. Currently can be list, pkg, xml, value or undefined. @foo._type
._ugly A string representing a 1010data input form of @variable (where possible).
._xml Returns the code corresponding to the MDB ops as an XML value.