Introduction
This article is a great place to start if you’re interested in working with list attributes in FME. Consider this your gateway where you’ll find introductory information as well as links to FME List Attribute documentation, example tutorials with workspace templates, and other FME resources related to List Attributes and data manipulation.
Explore the headings below to learn concepts related to list attributes and how using list attributes can simplify working with multiple attribute values.
What is a List? Why might you use one?
Lists permit an attribute to store more than one value in a structured way. For example, a generic text field named FRUITS can store a value like “Apple, Orange, Pear” but cannot be easily divided into its constituent parts of “Apple” “Orange” and “Pear”. This is where a list attribute excels. If the same attribute was structured as a list, it could be broken down into:
FRUITS{0}: Apple
FRUITS{1}: Orange
FRUITS{2}: Pear The number represents the value’s (or element’s) place (or index) inside the list. Within this structure, lists can be reorganized, exploded into individual parts, analyzed statistically, or counted according to the number of elements, to name a few options.
Lists are everywhere in FME. 15 transformers are dedicated to list manipulation, and over 80 transformers can produce lists. Using FME transformers and functionality, lists can be built manually, created automatically by a transformer, or exploded back into single-value attributes. Transformers often create a list automatically as part of the output from their particular process, usually when attributes from various different features are grouped into a single feature. FME lists can be displayed and inspected in the Data Inspector or using the Logger transformer.
For more on lists in FME, please see the following documentation pages:
List Articles
Take a look at the following articles for an in-depth look at list structures in FME as well as examples of list-based transformers and workflows. Each article contains a topic overview, sample workspaces and data, instructions or descriptions of workflows, and lots of visuals to guide you through the processes.
Creating Lists Using Transformers
This example demonstrates creating list attributes manually and introduces a few common transformers that can build lists.
Transformers for Working with List Attributes
Once you have a list, there are a number of transformers available for manipulating it. You’ll find examples of workspaces that manipulate and analyze lists in this article.
Related Resources
Pivoting Between Columns, Lists and Records
List Manipulation in FME (FME UC slideshow)
Dynamic Workflow Tutorial: Destination Schema is Derived from List Attributes
Hello,
I need to retrieve the information entered from a platform. To do this, I use the transform "HttpCaller" with the method GET, I get the contents of the file JSON (response_body).
At first, the idea would be to recover all files (id and status) from the url below:
https://www.demarches-simplifiees.fr/api/v1/procedures/12258/dossiers?token=VR5uoc8i2CcMVKbejP9vwtdA
And, in a second step, retrieve the details of each folder as a table from the following url:
https://www.demarches-simplifiees.fr/api/v1/procedures/12258/dossiers/268283?token=VR5uoc8i2CcMVKbejP9vwtdA
Each file will have a unique number, so I think this attribute must be variable.
Could someone tell me what to do?
Thank you !
Hello @bathie,
Thank you for your question. It sounds like you may be looking for resources related to parsing JSON or XML. Is this other question similar to yours: https://knowledge.safe.com/questions/89271/nested-geojson-extraction.html ? If yes, then please consider reviewing that question and the JSON tutorial or the XML tutorial. If you have further questions, please use New Question, for better visibility: https://knowledge.safe.com/questions/ask.html?space=155. Thank you!
