JSONExtractor

Allows for selecting between one of two options for JSON input: JSON Document or File/URL

If selected, The JSON document can come from any string expression, including attribute values and workspace parameters.

If selected, the JSON source can be read from a local file at a specified file path, or from the internet at a specified URL.

This parameter identifies the feature attribute into which the result of the JSON query should be put.  

This parameter is the JSON query whose value will be stored in the target attribute.

Each cell in the JSON Query column contains a button that opens a dialog containing the structure of the JSON dataset in a tree form. If the JSONExtractor is set to read from a file or URL, then selecting a value from the tree will populate the parameter with the appropriate query string to turn the selected values into features.

A JSON query is primarily used to refer to values in some JSON text. They can also be used to extract some metadata about the JSON text, such as the type (object, array, string, etc.) of JSON value or the number of elements in an array. The outermost JSON value, which must be an object or an array, is always referred to by the term "json".  Contained values can be referred to using JavaScript-like square bracket index operators.  

A value in an array can be referred to using its zero-based position in the array (for example, json[2] for the third element).

A value in an object can be referred to using its object key name

json["key"]

All of the values in an array or object can be collectively referred to using a wildcard index

json[*]

The query used by this transformer can have multiple expressions, which are separated by a '+' operator, as well as string literal values. This allows more complex attribute values to be easily created from the JSON text. For example:

json["name"]["first"] + " " + json["name"]["last"]

The JSONFragmenter transformer contains more information on JSON queries.

If the JSON query cannot be fully evaluated, a message will be logged, and the feature will be output without setting the target attribute.

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.

Note: Not all tools are available in all transformers.