AttributeFileWriter

Writes the contents of an attribute to a text or binary file.

Typical Uses

Writing files mid-workspace that contain the value of an attribute
Replacing a writer where the desired content is stored as an attribute
Writing images that have been stored as blob attributes
Writing coordinate system information to a file
Writing text lists of attribute values

How does it work?

The AttributeFileWriter receives any type of feature and writes the contents (value) of a specified attribute to an external file.

A Target Filename and encoding type must be specified. File names may be provided explicitly or by attribute value, expression, user parameter, or conditional value. If a target file already exists, it may be overwritten or appended to.

The attribute value and target file may be text or binary. A variety of encoding choices are available for text files. Binary files should be designated as Binary (fme-binary), as the transformer writes it as-is and will simply preserve the attribute contents as a Blob.

Examples

Example: Writing a text file appending values from multiple features

In this example, we have a shape file of city parks. Some of them are dog parks, and we want to write a text file containing all of their names.

Note that the source data has a number of attributes, including DogPark and ParkName.

This will take three steps:

Use a Tester to identify only the dog parks.
Add a carriage return to the park name with an AttributeManager.
Write a text file with the AttributeFileWriter.

In the parameters dialog of the Tester, we create one Test Clause, looking for DogPark = Y.

Next, we need to add a carriage return to the end of the attribute so that each one will be written on a separate line.

In the parameters dialog of an AttributeManager, we use the Text Editor to construct an expression that will add the special character to the existing ParkName attribute value.

The final step is to write the text file. In the parameters dialog of the AttributeFileWriter, we choose the ParkName attribute and set a Target Filename.

If Target File Exists is set to Append to file, and a text encoding is chosen.

The output file, as examined here in Notepad, contains the dog park names.

A variation on this would be to add <p> tags around each line, with a <br> tag line break, to write the output as very basic HTML.

Usage Notes

When writing any binary file types, ensure that Target File Encoding is set to Binary (fme-binary).
Full path names can be created from existing attribute values by using the Text Editor to create an expression.
The most common text encodings are Windows Latin-1 (windows-1252) and Unicode 8-bit (utf-8).
If you are unsure of the encoding used by the attribute, the Feature Information window in the FME Data Inspector will often help.

Configuration

Input Ports

Output Ports

Parameters

General

Source Attribute	Name of the attribute whose value will be written out to a file.
Target Filename	The name and location of the file to be written. It may be specified explicitly or by attribute value, expression, user parameter, or conditional value.
If Target File Exists	Specifies the action to take if the target file already exists. Overwrite file: Replace the existing file. Append to file: Add the current value to the end of the existing file. Note that when appending to a text file, you may want to add a special character (newline or carriage return) to the attribute value prior to the AttributeFileWriter.
Target File Character Encoding	The character encoding of the target file. The default encoding is System default (fme-default). Note that binary files must be specified as Binary (fme-binary) regardless of type.

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

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.

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.

Content Types

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

Table Tools

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.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
Aliases
History

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Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.