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Table of Contents

Background

We've already discussed how to add hypermedia to a resource using the standard HAL _links and _embedded reserved properties. These properties will cover the majority of your hypermedia needs. However, in this same article we introduced the AddFormAction service to address hypermedia requirements that go beyond the design intent of the _links and _embedded properties.

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In the above example, the intent of this form action is to describe how a new phone number can be added to the current resource. Clients should be able to consume this meta data and discover that this is done by sending a JSON object containing the type and number properties via a POST to the indicated URI.

fields Sub-Property

The fields sub-property contains one or more sub-properties. Each of these sub-properties are the names of a property in the primary resource object. In the above example, type and number are expected to be properties within the primary resource object. The sub-property values are themselves additional sub-property name/value pairs.

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• default to indicate the value of the resource object property that should be submitted unless overridden by the client.
• required to indicate that this resource object property must have a value in order for the form action to be accepted.
• visible to indicate if this resource object property should be visible to the client.

Hierarchical Outline

To help visualize the _forms structure, here is a general outline:

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