JSONFlattener

Categories

Format Specific

Web

Flattens JSON (JavaScript Object Notation) objects, extracting the object keys and values into FME feature attributes.

For example, consider a feature which has an attribute named json containing the following text:

{
   "paramName":"GeocodeResult",
   "dataType":"GPFeatureRecordSetLayer",
   "value":
   {
      "geometryType":"esriGeometryPoint",
      "spatialReference": {"wkid":4326 }
   }
}
 

After going through the JSONFlattener, the following attributes will have been added to the feature:

Attribute Name Attribute Value
paramName GeocodeResult
dataType GPFeatureRecordSetLayer
value.geometryType esriGeometryPoint
value.spatialReference.wkid 4326

Configuration

Output Ports

Features which are successfully processed will be output through this port.

Features which could not be successfully processed will be output through this port. Typically this happens when the attribute specified in the JSON Attribute parameter does not have a value, or has a value that is not valid JSON.

Parameters

Input Source

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

JSON Document

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

File/URL

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.

Recursively Flatten Objects/Arrays

If this parameter is set to No, each JSON object key will become an attribute and the corresponding JSON value will become the attribute value. If this parameter is set to Yes, only object values which are simple types (integers, strings, etc) will become attribute values, while nested objects and arrays will be recursively flattened, as shown in the above example.

Prefix New Attribute Names With

This parameter may be used to provide a string with which to prefix the newly-created attributes.

Attributes to Expose

Exposes any attributes so they can be used by other transformers. Type directly in the text box or click the browse button to display the editor and add attributes there.

List Attribute for JSON Parsing Errors

Name of the list attribute that contains information on JSON validation errors. The features that exit the transformer through the <Rejected> output port will have validation errors listed in this list attribute. Each validation error message is made up of four parts:

  • Error description
  • Line number where the error occurred
  • Column number where the error occurred
  • Error type/severity

Note: List attributes are not accessible from the output schema in FME Workbench unless they are first processed using a transformer that operates on them, such as ListExploder or ListConcatenator. Alternatively, AttributeExposer can be used.

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.

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.

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

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.

FME Community

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