useData

The hook for returning data for use in visualisations
Overview
The useData hook returns data from the engine for either KPIs or visualisations. For dimensions and measures to build charts, use the cols input and for expressions to build KPIs use the metrics input.
Basic Example
The below example returns data to the console for a number of Qlik dimensions and expressions.
  
 const cols = [{
      qField: "[OrderDateMonth]",
      qLabel: "Order Date",
    },
    {
      qField: "[Country",
      qLabel: "Body Location",
    },
    {
      qField: "=Sum(Price*Quantity)",
      qLabel: "price",
      qFillStyle: "orange",
    }]
​
  const {
    dataSet,
  } = useData({
    cols,
    qTitle,
  });
​
  console.log(dataSet)
​
// ...
KPI Example
See below for an example of how to get data from the engine to build a KPI. Here we are creating storing the output from two Qlik expressions into a variable called metrics. You can pass in expressions or variables to the hook.
 // .....
 
   const qMetrics = [{
    qName: "KPI 1",
    qExpr: "=$(vQuantity)",
    qType: "qStringExpression"
  },
  {
    qName: "KPI 2",
    qExpr: "=Sum(Price*Quantity)",
    qType: "qStringExpression"
  }]
​
  const {
    metrics,
  } = useData({
    qMetrics,
  });
​
  console.log('metric: ',metrics)
  
  //...
Master Items Example
If you are using Master Items from your Qlik Sense app, your cols config will be looking slightly different. See below for an example
import React from 'react'
import { useData } from '@motor-js/engine'
​
const MasterItemsExample = () => {
​
  const cols = [
  {
    qField: "[OrderDateMonth]",
    qLabel: "Order Date",
  },
  {
    qField: "",
    qLibraryId: "dWHamW",
    qType: "measure",
  }];
  
  const { dataSet, headerGroup } = useData({
    cols,
  });
​
 //....
Data Options
The following options can be passed into the hook
cols: Array
Optional
The columns in your Qlik application you wish to extract data for
Can be an array of strings or an array of objects
See Cols Options for the object definition
qPage: Object
Optional
Must be an object in the following structure: { qTop: num, qLeft: num, qWidth: num, qHeight: num }
Size of the extracted data from the engine
qTitle: string
Title of your visualisation
qSubtitle: string
Subtitle 
qMetrics: array<object>
An array of Metric objects
Expressions to calculate KPI values
See Metric Options for the object definition
Cols Options
qField: <string> | <array>
Required
Dimension or Measure name from your Qlik Sense data model
Pass an array to use a drill down group
qLibraryId: <string>
Use to refer to a Master Item created in your app
Must refer to the id of your Master Item
qType: <"dimension" | "measure">
Use along with qLibraryId, if you are using Master Items from your Qlik Sense data model
Required to label your qLibraryId as a dimension or measure
qLabel: <string>
Label of your dimension / measure. This will be available in the headerGroup object to use as your table's title
qGrouping: <oneOf>
N or GRP_NX_NONE
H or GRP_NX_HIEARCHY
C or GRP_NX_COLLECTION
Use H for a drill down group
qNumType: <oneOf>
U or UNKNOWN 
A or ASCII 
I or INTEGER 
R or REAL 
F or FIX 
M or MONEY 
D or DATE 
T or TIME 
TS or TIMESTAMP 
IV or INTERVAL
To set the number type of the returned text
qNumFmt: <string>
Format of number e.g. '$#,##0'
qFillStyle: <string>
Fill colour of your measure to be used in your chart
Metric Options
qName: string
Name of the metric
qExpr: string
Qlik expression to calculate a single value
qType: oneOf
qStringExpression
qValueExpression
Whether the expression should return a string or numeric value
Data Properties
The following properties are returned from the hook
DataSet: Array
An array of data objects, contains the data returned from the engine
The structure of this object can change depending on your cols input
See Data Properties for more details
DataKeys: Array
An array of data keys, contains the dimension names, which your measure is calculated across or the name of the measure. This depends on the number of dimensions and measures you are passing into cols.
See Data Keys Properties for more details
DataList: Array
See Data List Properties for more details
select: Function(column, [elemNumber], toggle)
A function to apply selections against the Qlik engine
You need to pass:
Column to apply selection against  Needs to be an array of the element numbers you wish to select
An array of element numbers to select
Whether to toggle selections, optional parameter, default set to false
Element numbers are equivalent to the elemNumber in the dataKey object, in dataSet
beginSelections: Function
A function to begin the selections mode, equivalent to this Qlik method
endSelections: Function
A function to end the selections mode, equivalent to this Qlik method
selections: Array
An array of selected element numbers
clearSelections: Function
Clears all selections for the particular dimension
metrics: Object
An object containing the output from Metric options (qMetrics array)
DataSet Properties
qElemNumber: Number
Element number of the data point relating to the primary dimension
label: String
Label of the data point
[dimensionOneName]: String
Primary dimension values
[dimensionTwoName]: String
Second dimension values. Will be present if two dimensions are passed into the cols object
[dimensionTwoName]-qElemNumber: Number
Element number associated to each of the second dimension data points
Will be present if two dimensions are passed into the cols object
[measureName]: String | Number
Measure value, will be present if only 1 dimension is passed into the cols object
key: Number
Unique key for each object in the DataSet array
DataKey Properties
[keyName]: string
Relates to a data point in each Data Object
Could be a measure name or list of dimension values depending on your cols definition
Data List Properties
Contains an array of dataKeyobjects. Please see Data Key Properties for more details
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