Views Handlers & Plugins

7/30/2019 Views Handlers & Plugins

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ViewsHandlers & Plug-ins

Sorin Dediu

Drupal developer


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Views handlers


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What is views handler

Handler is an object that is part of the view

and is part of the query building flow.

Most handlers are just extensions of existing

classes with a few tweaks that are specific to

the field in question.


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Handler registration

Handlers are stored in their own files and

loaded on demand. Like all other module files,

they must first be registered through the

module's info file.


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Handler registration

Put this in your module.info

files[] = includes/views/handlers/example_handler_argument_string.inc

Handler declaration format:

[module]_handler_[type]_[tablename]_[fieldname]


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Handler flows

Handlers have two distinct code flows:- the UI flow

- the view building flow


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The view building flow

For the query flow:

- handler->construct()

- Create the initial handler; at this time it is not yet attached to a view. It is here that

you can set basic defaults if needed, but there will be no knowledge of the

environment yet.- handler->set_definition()

- Set the data from hook_views_data() relevant to the handler.

- handler->init()

- Attach the handler to a view, and usually provides the options from the display.

- handler->pre_query()

- Run prior to the query() stage to do early processing.


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The view building flow

- handler->query()

- Do the bulk of the work this handler needs to do to add itself to the query.

Fields with output:

- handler->pre_render(&$values)

- Called prior to the actual rendering, this allows handlers to query for extra data;

the entire result set is available here, and this is where items that have "multiple

values" per record can do their extra query for all of the records available.

- handler->render()- This does the actual work of rendering the field.


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hook_views_data()


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Extend existing handler


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Views plugins


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What is view plugin

In Views, a plugin is a bit like a handler, but plugins are notdirectly responsible for building the query. Instead, they are

objects that are used to display the view or make other

modifications.


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What is view plugin

There are 12 types of plugins in Views:


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Views plugins types

Display

Style

Row Style Argument Default

Argument Validator

Access


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Views plugins types

Query

Cache

Pager plugins Exposed form plugins

Localization plugins

Display extenders


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hook_views_plugins()

Here is an example of a row style plugin from Views core:


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Pager plugin

Plugin type: pager


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THANK YOU

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Views Handlers & Plugins

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