XMLFlattener

Categories

Format Specific

Web

Flattens content of XML element(s) into feature attributes.

This transformer provides a quick and easy way to output any content or attributes of an XML element as feature attributes by specifying the element name or path. Optionally, the XML attributes from the ancestors of the specified elements can be fetched as FME attributes as well.

The XMLFlattener does not currently support multiple matches, so for generation of multiple features from the source XML, please use the XMLFragmenter.

Configuration

Input Ports

Input features that contain the XML document information.

Output Ports

Each feature will contain attributes that are flattened from the XML element(s).

Parameters

XML Source Type, XML File, XML Attribute

Selecting from the list enables that selection's corresponding parameter:

  • XML File: enables the XML File field.
  • XML Attribute: enables the XML Attribute field.

Elements to Match

This parameter specifies which elements to flatten. The Flatten Paths are whitespace-separated xfMap match expressions or each expression can be specified on a new line. For more information, see the FME Readers/Writers manual: XML (Extensible Markup Language) Reader/Writer > xfMap.

Type directly in the text box or click the browse button to display the editor or select Set to Attribute Value to pick a feature attribute containing the element expressions.

The Feature Paths are whitespace-separated xfMap match expressions. For more information, see the FME Readers/Writers manual: XML (Extensible Markup Language) Reader/Writer > xfMap.

Example: input.xml

<shiporder>
  <orderperson>John Smith</orderperson>
  <shipto>
    <name>Ola Nordmann</name>
    <address>Langgt 23</address>
    <city>4000 Stavanger</city>
    <country>Norway</country>
  </shipto>
  <item id="1" status=”pending”>
    <title>Empire Burlesque</title>
    <note>Special Edition</note>
    <quantity>1</quantity>
    <price>10.90</price>
  </item>
  <item id="2" status=”shipped”>
    <title>Hide your heart</title>
    <quantity>1</quantity>
    <price>9.90</price>
  </item>
</shiporder>

This table lists some Flatten Paths xfMap expressions shown in the above example.

"orderperson" Add the text content of orderperson element into orderperson feature attribute
"shipto" Add the text content of the children of shipto element into the following feature attributes: name, address, city and country.
“item[@id=1]” or equivalently <item id=“1”> This matches the element in the document named item whose attribute id is equal to 1. It adds the text content of the children as feature attributes: title, note, quantity and price.
“orderperson shipto <item id=“1”>” The three previous matched expressions combined, each separated by newline.

Elements as XML Fragments

This parameter can be specified to extract the children of the matched elements as xml fragments.

For example, If Elements to Match is shipto and Elements As XML Fragments is set to country , then the output feature has an extra attribute "xml_fragment_country{0}" with its value set to "<country>Norway</country>"

Flatten Options

The Options button opens the XML Flatten Options dialog. These options control how the content of the elements are to be mapped as feature attributes.

The default view is Basic mode, where several options are listed:

  • Enable Flattening is selected by default.
  • Ignore Specific Sub-Elements > Sub-Elements To Ignore: Specify the children of the matched elements (from Flatten Paths) that should be ignored. In the example above, if Flatten Paths is “shipto”, then if this option is set to “country city” then both country and city contents are ignored in the output.
  • Skip Empty Elements : specify whether empty elements should be mapped as empty feature attributes
  • Add Custom Prefix > Prefix: specify the prefix for all the feature attributes that will be added from the flattened XML structure
  • Include XML Child Position > Attribute Name: specify the attribute name whose value will be the position of the child element within its parent.
  • Add Ancestor Attributes > Ancestor Element(s) : specify the parent element(s) of the elements in Flatten Path whose XML attributes will also be added as feature attributes in the output.

The Advanced button opens the Advanced Editor, which provides additional options for customizing the feature attributes. The functionality of each option is described in the table below. The options here allow customization of the attributes and attribute lists of the matched XML subtree that will be added to FME Features.

Option (with example value) Description Default Value Possible Values

separator="."

This value of this option is used as the separator in the naming of the attributes of the children of the matched elements.

period (.)

any string

open-list-brace="{"

Specifies the open list index delimiter brace for the flattened attributes.

Default value if not specified: {

any string

close-list-brace="}"

Specifies the close list index delimiter brace for the flattened attributes.

Default value if not specified: }

any string

map-empty-elements="yes"

If set to yes, any empty elements will be added onto the features as attributes with empty values. Otherwise, the attributes will not be added onto the features.

Default value if not specified: yes

yes | no

Possible values: any string

matched-prefix="attributes"

This option controls whether FME feature attributes produced will be prefixed with matched element's name.

If the value is yes, then both the matched element's attributes and all its children are prefixed

If the value is no, then none of the feature attributes are prefixed with matched element's name

If the value is children, then only the children of the matched element are prefixed

If the value is attributes, then only the attributes of the matched element are prefixed.

Default value if not specified: yes

yes | no | children | attributes

matched-attributes="yes"

If this option is set to yes then the attributes of the matched element are mapped as FME feature attributes. Otherwise, the attributes of the matched element are ignored.

matched-prefix option can also be set to attributes or yes to allow the attributes to be prefixed with the name of the matched element.

Default value if not specified: yes

yes | no

matched-ancestor-attributes=""

The option controls whether XML attributes from ancestor of the matched element should be included as FME feature attributes.

- 'parent' or '1' : XML attributes of the parent of the matched element are added

- 'grandparent' or '2' : XML attributes of the grandparent of the matched element are added

- 'root' or '-1' : XML attributes of the root of the document are added

- any non-negative number : XML attributes of the ancestor by going up x levels from the matched element are added. 0 is the matched element.

To include more than one ancestor, multiple values can be separated by a space.

For example: To get the attributes from root, parent and grand parent, we can specify

matched-ancestor-attributes="parent grandparent root"

  

parent | grandparent | root

cardinality="+{?}"

This option can be specified as a space separated list of cardinality directives.

Default value: +{?} (Treat child elements as a list if there are more than one with the same name)

Possible values: Refer to the xfMap section in the XML Reader documentation.

except=""

The except attribute accepts the same types of expressions as the match or except attribute of a mapping rule.

For example, the expression except="parent/child{2}"€ could be used to exclude the second <child> element contained in a <parent> element from the output of the structure subrule.

  

any path expression

structure-prefix=""

This option can be set to non-empty string that serves as a prefix to every attribute that is generated for a matched element.

  

any string

child-position-attribute=""

When this option is set to non-empty string, each child element will generate an additional feature attribute whose value will be the position of the child element within its parent.

  

any string

attribute-identifier=""

XML attributes can be differentiated from leaf elements. By setting this option to a non-empty string, the XML reader will append a prefix to the attributes in the leaf elements.

    

All the options have more detailed examples and descriptions in the FME Readers/Writers manual: XML (Extensible Markup Language) Reader/Writer.

Ignore External DTD

Setting this parameter to Yes instructs the underlying XML parser to disable the loading of an external DTD.

Entity Resolver

By the default this parameter is Enabled and a custom entity resolver is used to resolve external entities such as DTDs.

The installed custom entity resolver relies on an URI Map that incoming URIs to resolved URIs. The resolved URIs are usually URLs with local copies of the resource.

If an XML document does not have any external entities that need to be resolved, this parameter may be Disabled and the URI Map will not be loaded unnecessarily.

Attributes to Expose

Exposes attributes so they can be used elsewhere in the workspace.

Attribute names may be entered directly or provided in the Enter Values for Attributes to Expose dialog accessed via the ellipsis button, where data type may also be specified.

For more information on exposed and unexposed attributes, see Understanding Feature Types and Attributes.

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

String Functions

These functions manipulate and format strings.

Special Characters

 A set of control characters is available in the Text Editor.

Math Functions

Math functions are available in both editors.
Date/Time Functions Date and time functions are available in the Text Editor.

Math Operators

These operators are available in the Arithmetic Editor.

FME Feature Functions

These return primarily feature-specific values.

FME Parameters

FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters Create your own editable parameters.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

  • Add a row
  • Remove a row
  • Move current row up one
  • Move current row down one
  • Move current row to top
  • Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

  • Cut a row - delete and copy to clipboard
  • Copy a row to the clipboard
  • Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

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