Power BI Dataview Transformer

It's not very easy to parse the dataview coming from Power BI Custom Visuals.

This library helps you transform the dataview object into an array of objects that is defined in your capabilities json.

For Example:
``json
{
"dataRoles": [
{
"displayName": "Width Data",
"name": "width",
"kind": "Measure"
},
{
"displayName": "Target Height Data",
"name": "targetHeight",
"kind": "Measure"
},
{
"displayName": "Actual Height Data",
"name": "actualHeight",
"kind": "Measure"
},
{
"displayName": "Label Name",
"name": "name",
"kind": "Grouping",
"preferredTypes": [
{
"text": true
}
]
}
],
...
}
`

The Transformed array will look like this

`js
[
{name: 'One', actualHeight: 10, targetHeight: 100, width: 15},
{name: 'One', actualHeight: 20, targetHeight: 200, width: 25},
{name: 'One', actualHeight: 30, targetHeight: 300, width: 35},
{name: 'One', actualHeight: 40, targetHeight: 400, width: 45}
]
`

How to Use

To Install: npm install --save powerbi-dataview-transformer

1. In pbiviz.json, Add "node_modules/powerbi-dataview-transformer/dist/index.js" under ExternalJS array.
1. In tsconfig.json, Add "node_modules/powerbi-dataview-transformer/types.d.ts" under files array.
1. Then in your visual.ts:

`ts
interface Window {
d3: typeof d3;
_: typeof _;
dataviewTransformer: typeof dataviewTransformer; // <-- this line
}

class Visual {
...

type Datum = {
name: string,
actualHeight: number,
targetHeight: number,
width: number
}

public update(options: VisualUpdateOptions) {
// parse data

const dataView: DataView = options.dataViews[0]
const transformedData = window.dataviewTransformer.categoryTransform(dataview, "id") // <-- "name" is the category that you want to select from your capabilities.json
// transformedData = [{name: 'One', width: 15, targetHeight: 100, actualHeight: 10}, ...]
}
}
`

API Doc

$3

#### Parameters
* dataview (required)
This is the dataview that is in the options object passed into the update function. Usually the dataview is found in options.dataviews[0] inside the update function.

* category name (required)
This is the value of name property of the category is defined in the capabilities.json file under dataRoles. The returned array is going to be an array of data objects that is based on this catagory.

* SelectionIdBuilder (optional)
SelectionIdBuilder is the function that exists in the options object that is passed in the constructor function. Since we need to pass this function in the update function. One approach is to create store the SelectionIdBuilder` in a class property, then use it in this function

#### Returns
* The function will return an array that is strongly typed to the datum shape you defined in your custom visual.