Cell Renderer
The job of the grid is to lay out the cells. By default the grid will create the cell values using simple text. If you want more complex HTML inside the cells then this is achieved using cell renderers.
This page explains first how to create cell renderers using standard JavaScript. It then continues on how to create cell renderers using components of different frameworks (eg how to create a cell renderer using a React or Angular component). If you intend to use the framework variant, you should first read the JavaScript sections as the framework sections build on this.
Simple Cell Renderer Example
The example below shows a simple cell renderer in action. It uses a cell renderer to show a hash '#' symbol instead of the medal count.
Cell Renderer Component
The interface for the cell renderer component is as follows:
The interface for the cell renderer parameters is as follows:
Below is a simple example of cell renderer class:
Registering Cell Renderers with Columns
See the section registering custom components for details on registering and using custom cell renderers.
Component Refresh
Component refresh needs a bit more explanation. Here we go through some of the finer details.
Events Causing Refresh
The grid can refresh the data in the browser, but not every refresh / redraw of the grid results in the refresh method of your cell renderer getting called. The following items are those that do cause refresh to be called:
-
Calling
rowNode.setDataValue(colKey, value)
to set a value directly onto therowNode
. This is the preferred API way to change one value from outside of the grid. - When editing a cell and editing is stopped, so that cell displays new value after editing.
-
Calling
api.refreshCells()
to inform grid data has changed (see Refresh).
If any of the above occur and the grid confirms the data has changed via
Change Detection, then the refresh()
method will be called.
The following will not result in the cell renderers refresh method getting called:
-
Calling
rowNode.setData(data)
to set new data into arowNode
. When you set the data for the whole row, then the whole row in the DOM is recreated again from scratch. - Scrolling the grid vertically causes columns (and their containing cells) to be removed and inserted due to column virtualisation.
All of the above will result in the component getting destroyed and recreated.
Change Detection
As mentioned in the section on Change Detection, the refresh of the cell will not take place if the value getting rendered has not changed.
Grid vs Component Refresh
The refresh method returns back a boolean value. If you do not want to handle the refresh in the
cell renderer, just return back false
from an otherwise empty method. This will indicate
to the grid that you did not refresh and the grid will instead rip the component out and destroy it
and create another instance of your component from scratch instead.
Cell Renderer Component Lifecycle
The lifecycle of the cell renderer is as follows:
new
is called on the class.init()
is called once.getGui()
is called 0 or 1 times (destroy could get called first, i.e. when scrolling quickly)refresh()
is called 0..n times (i.e. it may never be called, or called multiple times)destroy()
is called once.
In other words, new()
, init()
and
destroy()
are always called exactly once. getGui()
will typically get called once unless destroy()
is called first.
refresh()
is optionally called multiple times.
destroy()
it is important to check that any elements created in getGui()
exist, as when scrolling quickly
destroy()
can get called first. Calling getGui()
unnecessarily would negatively affect scroll performance.
If you are doing refresh()
, remember that getGui()
is only called once (assuming the cell renderer hasn't been destroyed first), so be sure
to update the existing GUI in your refresh, do not think that the grid is going to call getGui()
again to get a new version of the GUI.
Cell Rendering Flow
The diagram below (which is taken from the section Value Getters & Formatters) summarises the steps the grid takes while working out what to render and how to render.
In short, a value is prepared. The value comes using either the colDef.field
or the
colDef.valueGetter
. The value is also optionally passed through a colDef.valueFormatter
if it exists. Then the value is finally placed into the DOM, either directly, or by using the chosen
colDef.cellRenderer
.
Complementing Cell Renderer Params
On top of the parameters provided by the grid, you can also provide your own parameters. This is useful if you want to 'configure' your cell renderer. For example, you might have a cell renderer for formatting currency but you need to provide what currency for your cell renderer to use.
Provide params to a cell renderer using the colDef option cellRendererParams
.
Cell Renderers and Row Groups
If you are mixing cell renderers and row grouping, then you need to understand that the value and / or data
may be missing in the group row. You can check if you are on a group row of not by checking
rowNode.group
.
Groups will have aggData
and groupData
instead of data.
This is simply fixed by checking for the existence of the data before you use it like the following:
Cell Renderer Function
Instead of using a component, it's possible to use a simple function for a cell renderer.
The function takes the same parameters as the cell renderer init
method in the
component variant. The function should return back either a) a string of HTML or b) a DOM object.
Use the function variant of a cell renderer if you have no refresh or cleanup requirements (ie you don't need to implement the refresh or destroy functions).
If using a framework such as React or Angular for your cell renderers then you must provide a cell renderer component. There is no function equivalent for the frameworks such as React and Angular.
Below are some simple examples of cell renderers provided as simple functions:
Complex Cell Renderer Example
The example below shows five columns formatted, demonstrating each of the methods above.
- 'Month' column uses
cellStyle
to format each cell in the column with the same style. - 'Max Temp' and 'Min Temp' columns uses the Function method to format each cell in the column with the same style.
- 'Days of Air Frost' column uses the Component method to format each cell in the column with the same style
- 'Days Sunshine' and 'Rainfall (10mm)' use simple functions to display icons.
Accessing Cell Renderer Instances
After the grid has created an instance of a cell renderer for a cell it is possible to access that instance.
This is useful if you want to call a method that you provide on the cell renderer that has nothing to do
with the operation of the grid. Accessing cell renderers is done using the grid API
getCellRendererInstances(params)
.
An example of getting the cell renderer for exactly one cell is as follows:
Not that this method will only return instances of the cell renderer that exists. Due to row and column virtualisation, renderers will only exists for the user can actually see due to horizontal and vertical scrolling.
The example below demonstrates custom methods on cell renderers called by the application. The following can be noted:
-
The medal columns are all using the user defined
MedalCellRenderer
. The cell renderer has an arbitrary methodmedalUserFunction()
which prints some data to the console. - The Gold method executes a method on all instances of the cell renderer in the gold column.
-
The First Row Gold method executes a method on the gold cell of the first row only.
Note that the
getCellRendererInstances()
method will return nothing if the grid is scrolled past the first row. - The All Cells method executes a method on all instances of all cell renderers.
If your are using a framework component (detailed below), then the returned object
is a wrapper and you can get the underlying cell renderer using getFrameworkComponentInstance()
Angular Cell Render Components
It is possible to provide Angular cell renderers for ag-Grid to use if you are are using the Angular version of ag-Grid. See registering framework components for how to register framework components.
Example: Rendering using Angular Components
Angular Methods / Lifecycle
Your Angular components need to implement AgRendererComponent
.
The ag Framework expects to find the agInit
method on the created component, and uses it to supply the
cell params
.
All of the methods in the ICellRenderer
interface described above are applicable
to the Angular Component with the following exceptions:
init()
is not used. Instead implement theagInit
method (on theAgRendererComponent
interface).destroy()
is not used. Instead implement the AngularOnDestroy
interface (ngOnDestroy
) for any cleanup you need to do.getGui()
is not used. Instead do normal Angular magic in your Component via the Angular template.
Handling Refresh
To handle refresh, implement logic inside the refresh()
method inside your component and return true.
If you do not want to handle refresh, just return false from the refresh method (which will tell the grid you do
not handle refresh and your component will be destroyed and recreated if the underlying data changes).
Example: Rendering using more complex Angular Components
Using more complex Angular Components in the Cell Renderers - specifically how you can use nested NgModule
's
within the grid.
React Cell Rendering
It is possible to provide React cell renderers for ag-Grid to use if you are are using the React version of ag-Grid. See registering framework components for how to register framework components.
Example: Rendering using React Components
Using React Components in the Cell Renderers
React Props
The React component will get the 'Cell Renderer Params' as described above as its React Props. Therefore you can access all the parameters as React Props.
React Methods / Lifecycle
All of the methods in the ICellRenderer
interface described above are applicable
to the React Component with the following exceptions:
init()
is not used. Instead use the React props passed to your Component.destroy()
is not used. Instead use the ReactcomponentWillUnmount()
method for any cleanup you need to do.getGui()
is not used. Instead do normal React magic in yourrender()
method..
Handling Refresh
To handle refresh, implement logic inside the refresh()
method inside your component and return true.
If you do not want to handle refresh, just return false from the refresh method (which will tell the grid you do
not handle refresh and your component will be destroyed and recreated if the underlying data changes).
VueJS Cell Rendering
It is possible to provide VueJS cell renderers for ag-Grid to use if you are are using the VueJS version of ag-Grid. See registering framework components for how to register framework components.
Example: Rendering using VueJS Components
Using VueJS Components in the Cell Renderers
VueJS Methods / Lifecycle
All of the methods in the ICellRenderer
interface described above are applicable
to the VueJS Component with the following exceptions:
init()
is not used. The cells value is made available implicitly via a data field calledparams
.getGui()
is not used. Instead do normal VueJS magic in your Component via the VueJS template.
Refresh
There are two ways in which cell renderers can be refreshed:
- Implement the
refresh
method - Use the
autoParamsRefresh
mechanism - Do neither of the above - in which case the grid will destroy and recreate the cell each time the cell value changes
Implement the refresh
method
Within the methods
section of your component you can implement the refresh()
method which returns a boolean
value.
If you want to manage the refresh yourself return true
and if you want to let the grid manage the refresh return false
(the default behaviour).
Returning false
indicates that you do not wish to manage the refresh - in this case your component will be destroyed and recreated if the underlying data changes).
Enable autoParamsRefresh
on your renderer
You can set the autoParamsRefresh
property on the ag-grid-vue
component. If you do this then the grid will automatically refresh the component, updating the supplied
params
of the component.
This has the same effect as if you implemented the refresh
method as follows:
Setting this on your renderer to refresh automatically without the cost of the component being destroyed and re-created, but without the
need of implementing refresh
yourself.
Note that if you enable autoParamsRefresh
then this.params
will be updated and your version of refresh
will then be invoked.
Polymer Cell Rendering
It is possible to provide Polymer cell renderers for ag-Grid to use if you are are using the Polymer version of ag-Grid. See registering framework components for how to register framework components.
Example: Rendering using Polymer Components
Using Polymer Components in the Cell Renderers
Polymer Methods / Lifecycle
All of the methods in the ICellRenderer
interface described above are applicable
to the Polymer Component with the following exceptions:
init()
is not used. Instead implement theagInit
method.getGui()
is not used. Instead do normal Polymer magic in your Component via the Polymer template.
Handling Refresh
To handle refresh, implement logic inside the refresh()
method inside your component and return true.
If you do not want to handle refresh, just return false from the refresh method (which will tell the grid you do
not handle refresh and your component will be destroyed and recreated if the underlying data changes).