Data Handlers¶
In order to facilitate the custom handling of data we have introduced the concept of datahandlers. Datahandlers are functions that transform data - they can accept arbitrary paramaters, and have access to the following arguments:
datahandler definition¶
Datahandlers are defined as props at the component level - props.datahandlers is defined as an array of objects, where each object consists of a name property, as well as any number of additional properties, which are passed to the datahandler function as properties of the handler argument.
Consider:
``javascript // settings.js: { type: ‘Metric’, caption: ‘My Cool Metric’, dataHandlers: [ { name: ‘getRandomMetric’ }, { name: ‘multiplyByFactor’, factor: 2 }, { name: ‘multiplyByFactor’, factor: 4 } ] }
Take a look at examples/customDatahandlers.js for an example implementation.
## datahandler arguments
### componentData
Data set on the component as this.state.data - this could come from a fetch call, be passed as props, or through some novel method on a custom component.
### dashboardData
Also referred to as globalData - this is the data available to the entire dashboard
### handler
The handler as deffined in settings.js. Any properties set on the handler are available as `handler.foo`, etc
### e
Filters use the *e* property to capture the javascript event and pass it along for use in the handler
### appliedFilters
A global property of the dashboard which indicates what filters are applied at the global level. This object is pf the form:
```javascript
{
filterValueOne: ["val1", "val2"],
filterValueTwo: ["val3"]
}
chaining¶
If the component.props.dataHandlers array has more than one datahandler then the return value from the first handler will be passed as pipelineData to subsequent handlers, in this way composition of components is possible, etc.