AttributeFileReader

Reads the contents of an external text or binary file and attaches it to a feature as the value of an attribute.

Typical Uses

Attaching files to features
Adding file contents to features
Reading geometry content stored in a separate file

How does it work?

The AttributeFileReader receives any type of feature and adds the contents of an external file to them, as the value of a new or existing attribute.

File selection may be done explicitly or by attribute value, expression, user parameter, or conditional value.

The file may be text or binary. (Text refers to the file type, rather than the file content - it may not necessarily be plain text.) A variety of encoding choices are available for text files. Binary files should be designated as Binary (fme-binary), as the transformer is not aware of formats and will simply preserve the file contents as a Blob.

There is no file size limit. Very large files may affect performance, and need sufficient memory to hold them as no file caching is done.

Examples

Example: Attaching a text file as an attribute

In this example, we will read a text file and add it to a raster feature as an attribute. We want to add a palette (the text file) to a numeric raster in GeoTIFF format.

The raster is first routed through a RasterBandInterpretationCoercer to meet processing requirements - the band type must be an unsigned integer to be compatible with palettes.

Next, the raster is passed to an AttributeFileReader. Note that it has one exposed attribute and consists of one numeric band, an 8-bit unsigned integer.

A text file containing the palette information has already been prepared, as shown here in Notepad.

In the parameters dialog of the AttributeFileReader, we keep the default File Contents attribute name as_file_contents, and select the Palette_color.txt file.

As this is a text file, prepared on the same computer it is being processed on, we can use the System Default (fme-system) encoding.

Examining the output from the AttributeFileReader, note that the raster now has an additional attribute, _file_contents, which contains the contents of the text file.

The last step in this workflow is to apply the palette from the new attribute with a RasterPaletteAdder.

Example: Attaching an image to a feature

In this example, we have both a point cloud and an orthoimage of the same area, and want to keep them together - so we will attach the image to the point cloud feature as an attribute.

Note that the point cloud has one exposed attribute.

The orthoimage is a GeoTIFF.

The point cloud is routed into an AttributeFileReader.

In the parameters dialog, we keep the default File Contents attribute name as_file_contents, and select the StadiumOrthoLowRes.tif file.

Source File Character Encoding is set to Binary (fme-binary), which will store the GeoTIFF as a Blob.

Examining the output in the FME Data Inspector, note that the point cloud has a new attribute which contains the orthoimage, still encoded in binary.

From here, the image can be decoded and used at any time with a RasterReplacer, as in the example below which would use the raster to color the points of the point cloud with a PointCloudOnRasterComponentSetter. Another subsequent use could be writing it to a Blob column in a database.

Usage Notes

All types of binary files are stored as Blobs, and Source File Character Encoding should be set to Binary (fme-binary) .
The most common text encodings are Windows Latin-1 (windows-1252) and Unicode 8-bit (utf-8).
If a text file includes special characters, the appropriate Source File Character Encoding should be selected to preserve those characters.
Full path names can be created from existing attribute values by using the Text Editor to create an expression.
Some transformers (such as the XMLFlattener) can read external files, and so do not need to use an AttributeFileReader first.

Configuration

Input Ports

Output Ports

Parameters

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.