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Field Type API

eZ Platform can support arbitrary data to be stored in the fields of a content item. In order to support custom data, besides the standard data types, a developer needs to create a custom Field Type.

The implementation of a custom Field Type is done based on the FieldType SPI and its interfaces. These can be found under eZ\Publish\SPI\FieldType.

In order to provide custom functionality for a Field Type, the SPI interacts with multiple layers of the eZ Platform architecture, as shown in the following diagram:

Field Type Overview

On the top layer, the Field Type needs to provide conversion from and to a simple PHP hash value to support the REST API. The generated hash value may only consist of scalar values and hashes. It must not contain objects or arrays with numerical indexes that aren't sequential and/or don't start with zero.

Below that, the Field Type must support the Public API implementation (aka Business Layer), regarding:

  • Settings definition for FieldDefinition
  • Value creation and validation
  • Communication with the Persistence SPI

On the bottom level, a Field Type can additionally hook into the Persistence SPI, in order to store data from a FieldValue in an external service. Note that all non-standard eZ Platform database tables (e.g. ezurl) will be considered as external storage.

The following sequence diagrams visualize the process of creating and publishing a new Content across all layers, especially focused on the interaction with a Field Type.

Create Content Sequence

Create Content Sequence

Publish Content Sequence


indexLocation() is implemented for ElasticSearch only. For Solr Locations are indexed during Content indexing. For Legacy/SQL indexing is not required as Location data already exists in a database.

Publish Content Sequence

In the next paragraphs, this document explains how to implement a custom Field Type based on the SPI and what is expected from it. Please refer to the Url Field Type, which has been implemented as a reference code example.

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