Referencing Field Names and Field Paths

When a is valid for preview, you can generally select fields from a list. When a list is not available or when you are defining a new field name, you need to use the appropriate format for the field name.

Tip: After running preview for a , you can also copy a field path from the preview results or when you view the input and output schema for a stage input and output schema for a stage.

To reference a field, you specify the path of the field. A field path describes a data element in a record using a syntax similar to files in directories. The complexity of a field path differs based on the type of data in the record:

Simple maps or JSON objects

With simple maps or JSON objects, the fields are one level removed from the root. Reference the field as follows:

/<field name>

So, to reference a CITY field in a simple JSON object, enter /CITY. A simple expression that calls the field might look like this:

${record:value('/CITY')}

Complex maps or JSON objects

To reference a field in a complex map or JSON object, include the path to the field, as follows:

/<path to field>/<field name>

For example, the following field path describes an employeeName field several levels deep in a JSON object: /region/division/group/employeeName. An expression that calls the field might look like this:

${record:value("/region/division/group/employeeName")}

Arrays or lists

To reference a field in an array or list, include the index and path to the field, as follows:

[<index value>]/<path to field>/<field name>

For example, the following field path describes the same employeeName field in the third region index in an array: [2]/east/HR/employeeName.

An expression that calls the field might look like this:

${record:value('[2]/east/HR/employeeName')}

Delimited records can be structured as lists. For more information, see Delimited Data Root Field Type.

Text

To reference text when a record is a line of text, use the following field name:

/text