silverstripe-framework/docs/en/reference/grid-field.md
2013-06-19 16:48:49 +02:00

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# Gridfield
Gridfield is SilverStripe's implementation of data grids. Its main purpose is to display tabular data
in a format that is easy to view and modify. It can be thought of as a HTML table with some tricks.
It's built in a way that provides developers with an extensible way to display tabular data in a
table and minimise the amount of code that needs to be written.
In order to quickly get data-focused UIs up and running,
you might also be interested in the [/reference/modeladmin](ModelAdmin) class
which is driven largely by the `GridField` class explained here.
## Overview
The `GridField` is a flexible form field for creating tables of data. It was introduced in
SilverStripe 3.0 and replaced the `ComplexTableField`, `TableListField`, and `TableField` from
previous versions of SilverStripe.
Each GridField is built from a number of components. Without any components, a GridField has almost no
functionality. The components are responsible for formatting data to be readable and also modifying it.
A gridfield with only the `GridFieldDataColumn` component will display a set of read-only columns
taken from your list, without any headers or pagination. Large datasets don't fit to one
page, so you could add a `GridFieldPaginator` to paginatate the data. Sorting is supported by adding
a `GridFieldSortableHeader` that enables sorting on fields that can be sorted.
This document aims to explain the usage of GridFields with code examples.
<div class="hint" markdown='1'>
GridField can only be used with datasets that are of the type `SS_List` such as `DataList`
or `ArrayList`
</div>
## Creating a base GridField
A gridfield is often setup from a `Controller` that will output a form to the user. Even if there
are no other HTML input fields for gathering data from users, the gridfield itself must have a
`Form` to support interactions with it.
Here is an example where we display a basic gridfield with the default settings:
:::php
class GridController extends Page_Controller {
static $allowed_actions = array('index', 'AllPages');
public function index(SS_HTTPRequest $request) {
$this->Content = $this->AllPages();
return $this->render();
}
public function AllPages() {
$gridField = new GridField('pages', 'All pages', SiteTree::get());
return new Form($this, "AllPages", new FieldList($gridField), new FieldList());
}
}
__Note:__ This is example code and the gridfield might not be styled nicely depending on the rest of
the css included.
This gridfield will only contain a single column with the `Title` of each page. Gridfield by default
uses the `DataObject::$display_fields` for guessing what fields to display.
Instead of modifying a core `DataObject` we can tell the gridfield which fields to display by
setting the display fields on the `GridFieldDataColumns` component.
:::php
public function AllPages() {
$gridField = new GridField('pages', 'All pages', SiteTree::get());
$dataColumns = $gridField->getConfig()->getComponentByType('GridFieldDataColumns');
$dataColumns->setDisplayFields(array(
'Title' => 'Title',
'URLSegment'=> 'URL',
'LastEdited' => 'Changed'
));
return new Form($this, "AllPages", new FieldList($gridField), new FieldList());
}
We will now move onto what the `GridFieldConfig`s are and how to use them.
----
## GridFieldConfig
A gridfields's behaviour and look all depends on what config we're giving it. In the above example
we did not specify one, so it picked a default config called `GridFieldConfig_Base`.
A config object is a container for `GridFieldComponents` which contain the actual functionality and
view for the gridfield.
A config object can be either injected as the fourth argument of the GridField constructor,
`$config` or set at a later stage by using a setter:
:::php
// On initialisation:
$gridField = new GridField('pages', 'All pages', SiteTree::get(), GridFieldConfig_Base::create());
// By a setter after initialisation:
$gridField = new GridField('pages', 'All pages', SiteTree::get());
$gridField->setConfig(GridFieldConfig_Base::create());
The framework comes shipped with some base GridFieldConfigs:
### GridFieldConfig_Base
A simple read-only and paginated view of records with sortable and searchable headers.
:::php
$gridField = new GridField('pages', 'All pages', SiteTree::get(), GridFieldConfig_Base::create());
The fields displayed are from `DataObject::getSummaryFields()`
### GridFieldConfig_RecordViewer
Similar to `GridFieldConfig_Base` with the addition support of:
- View read-only details of individual records.
The fields displayed in the read-only view is from `DataObject::getCMSFields()`
:::php
$gridField = new GridField('pages', 'All pages', SiteTree::get(), GridFieldConfig_RecordViewer::create());
### GridFieldConfig_RecordEditor
Similar to `GridFieldConfig_RecordViewer` with the addition support of:
- Viewing and changing an individual records data.
- Deleting a record
:::php
$gridField = new GridField('pages', 'All pages', SiteTree::get(), GridFieldConfig_RecordEditor::create());
The fields displayed in the edit form are from `DataObject::getCMSFields()`
### GridFieldConfig_RelationEditor
Similar to `GridFieldConfig_RecordEditor`, but adds features to work on a record's has-many or
many-many relationships. As such, it expects the list used with the `GridField` to be a
`RelationList`. That is, the list returned by a has-many or many-many getter.
The relations can be:
- Searched for existing records and add a relationship
- Detach records from the relationship (rather than removing them from the database)
- Create new related records and automatically add them to the relationship.
:::php
$gridField = new GridField('images', 'Linked images', $this->Images(), GridFieldConfig_RelationEditor::create());
The fields displayed in the edit form are from `DataObject::getCMSFields()`
## GridFieldComponents
GridFieldComponents the actual workers in a gridfield. They can be responsible for:
- Output some HTML to be rendered
- Manipulate data
- Recieve actions
- Display links
Components are added and removed from a config by setters and getters.
:::php
$config = GridFieldConfig::create();
// Add the base data columns to the gridfield
$config->addComponent(new GridFieldDataColumns());
$gridField = new GridField('pages', 'All pages', SiteTree::get(), $config);
It's also possible to insert a component before another component.
:::php
$config->addComponent(new GridFieldFilterHeader(), 'GridFieldDataColumns');
Adding multiple components in one call:
:::php
$config->addComponents(new GridFieldDataColumns(), new GridFieldToolbarHeader());
Removing a component:
:::php
$config->removeComponentsByType('GridFieldToolbarHeader');
For more information, see the [API for GridFieldConfig](http://api.silverstripe.org/3.0/framework/GridFieldConfig.html).
Here is a list of components for generic use:
- `[api:GridFieldToolbarHeader]`
- `[api:GridFieldSortableHeader]`
- `[api:GridFieldFilterHeader]`
- `[api:GridFieldDataColumns]`
- `[api:GridFieldDeleteAction]`
- `[api:GridFieldViewButton]`
- `[api:GridFieldEditButton]`
- `[api:GridFieldPaginator]`
- `[api:GridFieldDetailForm]`
## Creating a custom GridFieldComponent
A single component often uses a number of interfaces.
### GridField_HTMLProvider
Provides HTML for the header/footer rows in the table or before/after the template.
Examples:
- A header html provider displays a header before the table
- A pagination html provider displays pagination controls under the table
- A filter html fields displays filter fields on top of the table
- A summary html field displays sums of a field at the bottom of the table
### GridField_ColumnProvider
Add a new column to the table display body, or modify existing columns. Used once per record/row.
Examples:
- A data columns provider that displays data from the list in rows and columns.
- A delete button column provider that adds a delete button at the end of the row
### GridField_ActionProvider
Action providers runs actions, some examples are:
- A delete action provider that deletes a DataObject.
- An export action provider that will export the current list to a CSV file.
### GridField_DataManipulator
Modifies the data list. In general, the data manipulator will make use of `GridState` variables
to decide how to modify the data list.
Examples:
- A paginating data manipulator can apply a limit to a list (show only 20 records)
- A sorting data manipulator can sort the Title in a descending order.
### GridField_URLHandler
Sometimes an action isn't enough, we need to provide additional support URLs for the grid. It
has a list of URL's that it can handle and the GridField passes request on to URLHandlers on matches.
Examples:
- A pop-up form for editing a record's details.
- JSON formatted data used for javascript control of the gridfield.
## GridField_FormAction
This object is used for creating actions buttons, for example a delete button. When a user clicks on
a FormAction, the gridfield finds a `GridField_ActionProvider` that listens on that action.
`GridFieldDeleteAction` have a pretty basic implementation of how to use a Form action.
### GridState
Gridstate is a class that is used to contain the current state and actions on the gridfield. It's
transfered between page requests by being inserted as a hidden field in the form.
A GridFieldComponent sets and gets data from the GridState.
## Related
* [ModelAdmin: A UI driven by GridField](/reference/modeladmin)
* [Tutorial 5: Dataobject Relationship Management](/tutorials/5-dataobject-relationship-management)