Explodes each list member on each input feature out into its own feature.
Any attributes on the list are copied to become non-list attributes of the feature output. In addition, the element number of the attributes in the original list is added to the feature. Each feature's output has a copy of the geometry from the original input feature.
- If Input attributes and list element attributes have the same name, the Input attributes will be overwritten by the list element attributes.
- ListExploder will not work with an invalid list, such as one that doesn't start at entry 0. For example:
| Valid List | Invalid List |
| mylist{0}.attr1 | mylist{1}.attr1 |
| mylist{1}.attr1 | mylist{2}.attr1 |
| mylist{2}.attr1 | mylist{3}.attr1 |
| mylist{3}.attr1 | mylist{4}.attr1 |
Examples
Example 1
If this feature enters this transformer:
somelist{0}.length = 7.3
somelist{0}.kind = ’paved’
somelist{1}.length = 8.4
somelist{1}.kind = ’smooth’
somelist{1}.lanes = 2
somelist{2}.length = 1.1
somelist{2}.kind = ’rough’
another_attr = ’something else’
then, presuming that the list name specified was somelist{}, the index attribute was element_num, and the Accumulation Mode parameter was set to Merge List Attributes, the first returned feature would look like:
length = 7.3
kind = ’paved’
element_num = 0
another_attr = ’something else’
If the Accumulation Mode parameter was set to Only Use List Attributes, the first returned feature would look like:
length = 7.3
kind = ’paved’
element_num = 0
Example 2
Suppose you have a Input feature with the following 6 attributes. (The List Attribute used here would be ID{}.)
Name
Type
ID{0}.dec
ID{0}.hex
ID{1}.dec
ID{1}.hex
Merge List Attributes will produce elements with 4 attributes:
Name
Type
dec
hex
Only Use List Attributes will produce elements with 2 attributes:
dec
hex
Configuration
Input Ports
Input
Features containing list members.
Output Ports
Elements
If the list is found in the input feature, it will be processed based on Accumulation Mode and output via this port.
<Rejected>
If the list is not found in the input feature, the feature will be output via this port without being processed. In this case, the Accumulation Mode parameter will not be applied and the transformer will pass the feature through without processing it.
Parameters
General
|
List Attribute |
The name of the list that will be exploded by this transformer. |
Attribute Accumulation
|
Accumulation Mode |
Merge List Attributes: The feature retains all of its own un-conflicted attributes, and additionally acquires any un-conflicted attributes generated by the transformer. This mode handles conflicted attributes according to the Conflict Resolution parameter. Prefix List Attributes: The feature retains all of its own attributes. In addition, the feature acquires attributes generated by the transformer, with the name prefixed with the Prefix parameter. Only Use List Attributes: All of the feature's attributes are removed, except geometry attributes that start with fme_. Then, the feature acquires all of the attributes and associated values that are generated from the exploded list attribute. |
|
Conflict Resolution |
Use Original Attribute Values: If a conflict occurs, maintain the values of the original, non-list attribute. Use List Attribute Values: If a conflict occurs, transfer the values of the generated attributes onto the original, non-list attributes. |
|
Prefix |
If the Accumulation Mode parameter is set to Prefix List Attributes, this value prefixes attributes that are added to the feature. |
Output Attribute Name
|
Element Index |
If the Element Index Attribute is specified, then each element feature output will be given an attribute containing the element's list position. |
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.
How to Set Parameter Values
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.
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.
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.
Content Types
| These functions manipulate and format strings. | |
|
Special Characters |
A set of control characters is available in the Text Editor. |
| Math functions are available in both editors. | |
| Date/Time Functions | Date and time functions are available in the Text Editor. |
| These operators are available in the Arithmetic Editor. | |
| These return primarily feature-specific values. | |
| 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.
Table Tools
|
Row Reordering
|
Enabled once you have clicked on a row item. Choices include:
|
|
Cut, Copy, and Paste
|
Enabled once you have clicked on a row item. Choices include:
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.
FME Community
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