Basic example of Google Charts with DataFlex WebApp

By Mike Peat

Below we will create a DataFlex wrapper component for the Google Charts component.

A wrapper consists of multiple parts working together, so that you can use the control directly from your DataFlex web application.

The javascript part

Create a new folder GoogleCharts in your AppHtml folder and put the following in the file Charts.js

(AppHTML\GoogleCharts\Charts.js):

if (!myCharts) {  // Configure namespace if not already defined
    var myCharts = {};
}

myCharts.chart = function chart(sName, oParent) {
    // Forward send constructor
    myCharts.chart.base.constructor.call(this, sName, oParent);
    
    // Load the Visualization API and the corechart package.
    google.charts.load('current', {'packages':['corechart']});

    // Properties:
    this.prop(df.tString, "psTitle",       "");
    this.prop(df.tInt,    "piChartHeight", 0);
    this.prop(df.tInt,    "piChartWidth",  0);
    this.prop(df.tString, "psChartType",  "");
    
    // Private:
    this._eWrap         = null;
    this._eCols         = [];
    this._eData         = [];

    //  Configure super classes
    this._sControlClass = "chart";
};

df.defineClass("myCharts.chart", "df.WebBaseControl", {

    openHtml : function(aHtml) {
        // Forward send
        myCharts.chart.base.openHtml.call(this, aHtml);
        
        aHtml.push('<div class="chart-wrp">');
        aHtml.push('    <div id="', this.psHtmlId, 'chartDiv"', ' style="height: 100%;"></div>');
        aHtml.push('</div>');
    },
    
    afterRender : function() {
        this._eControl = df.dom.query(this._eElem, "div.chart-wrp > div");
        this._eWrap = df.dom.query(this._eElem, "div.chart-wrp");

        // Forward send
        myCharts.chart.base.afterRender.call(this);
    },

    initalize : function() {
        this._eCols = [];
        this._eData = [];
    },

    addColumn : function(sName, iType) {
        var i = this._eCols.length;
        this._eCols[i] = [iType, sName];
    },


    addData : function(sName, nValue) {
        var i = this._eData.length;
        this._eData[i] = [sName, Number(nValue)]
    },


    drawChart : function() {
         myCharts.obj = this;
        // Set a callback to run when the Google Visualization API is loaded.
        google.charts.setOnLoadCallback(this.chartDef);
    },


    chartDef : function() {
        var data = new google.visualization.DataTable();
        var options, chart, obj = myCharts.obj;

        for (var i = 0; i < obj._eCols.length; i++) {
            data.addColumn(obj._eCols[i][0], obj._eCols[i][1]);
        }

        data.addRows(obj._eData);

        options = {
            title  : obj.psTitle,
            width  : obj.piChartWidth,
            height : obj.piChartHeight
        };

        switch (obj.psChartType) {
            case "PieChart":
                chart = new google.visualization.PieChart(obj._eControl);
                break;
            case "BarChart":
                chart = new google.visualization.BarChart(obj._eControl);
                break;
            case "AreaChart":
                chart = new google.visualization.AreaChart(obj._eControl);
                break;
            default:
                chart = new google.visualization.PieChart(obj._eControl);
        }

        chart.draw(data, options);
    }


});

The DataFlex counterpart class

Create a new file called cWebChart.pkg in the AppSrc folder and copy the following in there.

DataFlex class (AppSrc\cWebChart.pkg):

Use cWebBaseControl.pkg
Use cJsonObject.pkg  // Just to get the types

Define C_chartTypePie  for "PieChart"
Define C_chartTypeBar  for "BarChart"
Define C_chartTypeArea for "AreaChart"
// etc...

Class cWebChart is a cWebBaseControl
    
    Procedure Construct_Object
        Forward Send Construct_Object
        
        { WebProperty=Client }
        Property String  psTitle
        { WebProperty=Client }
        Property Integer piChartHeight
        { WebProperty=Client }
        Property Integer piChartWidth
        { WebProperty=Client }
        Property String  psChartType
        
        Set psJSClass to "myCharts.chart"
    End_Procedure
    
    Procedure Initalize
        Send ClientAction "initalize"
    End_Procedure
    
    Procedure AddColumn String sName Integer iType
        String[] asParams
        String   sType
        
        Case Begin
            Case (iType = jsonTypeString)
                Move "string"   to sType
                Case Break
            Case (iType = jsonTypeInteger)
                Move "number"   to sType
                Case Break
            Case (iType = jsonTypeInteger)
                Move "number"   to sType
                Case Break            
            Case (iType = jsonTypeDouble)
                Move "number"   to sType
                Case Break
            Case (iType = jsonTypeBoolean)
                Move "boolean"  to sType
                Case Break
            Case Else
                Move "string" to sType
        Case End
        
        Move sName to asParams[0]
        Move sType to asParams[1]
        Send ClientAction "addColumn" asParams
    End_Procedure
    
    Procedure AddData String sName Number nValue
        String[] asParams
        
        Move sName  to asParams[0]
        Move nValue to asParams[1]
        Send ClientAction "addData" asParams
    End_Procedure
    
    Procedure DrawChart
        Send ClientAction "drawChart"
    End_Procedure


End_Class

An example web object

Use cWebView.pkg
Use cWebPanel.pkg
Use cWebForm.pkg 
Use cWebButton.pkg
Use cWebChart.pkg
Use cWebRadio.pkg

Object oChart is a cWebView
    Set piWidth to 700
    Set psCaption to "Chart"
    
    Delegate Set phoDefaultView to Self

    Object oWebMainPanel is a cWebPanel
        Set piColumnCount to 12

        Object oPie is a cWebRadio
            Set piColumnSpan to 3
            Set psCaption to "Pie Chart"
            Set psRadioValue to C_chartTypePie
        End_Object

        Object oBar is a cWebRadio
            Set piColumnSpan to 3
            Set piColumnIndex to 3
            Set psCaption to "Bar Chart"
            Set psRadioValue to C_chartTypeBar
        End_Object

        Object oArea is a cWebRadio
            Set piColumnSpan to 3
            Set piColumnIndex to 6
            Set psCaption to "Area Chart"
            Set psRadioValue to C_chartTypeArea
        End_Object

        Object oDrawChart is a cWebButton
            Set piColumnSpan to 2
            Set psCaption to "Show Chart"
        
            Procedure OnClick
                String sType
                
                Send Initalize of oChart
                
                WebGet psValue of oPie to sType
                
                WebSet psTitle of oChart        to "How Much Pizza I Ate Last Night"
                WebSet piChartHeight of oChart  to 500
                WebSet piChartWidth  of oChart  to 600
                WebSet psChartType   of oChart  to sType
                
                Send AddColumn of oChart "Topping" jsonTypeString
                Send AddColumn of oChart "Slices"  jsonTypeInteger
                
                Send AddData   of oChart "Mushrooms"    6
                Send AddData   of oChart "Onions"       3
                Send AddData   of oChart "Olives"       2
                Send AddData   of oChart "Frogs Legs"   1
                Send AddData   of oChart "Pepperoni"    4
                Send AddData   of oChart "Anchovies"    5
                
                Send DrawChart of oChart
            End_Procedure
            
        End_Object
        
        Object oChart is a cWebChart
        End_Object
        
    End_Object 

End_Object

Add new control to your app

In order to be able to use that new control, you have to add it to the index.html file like so:

    ...

    <!-- DataFlex Custom Controls (do not remove this line, used for automatic insertion) -->
    <script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>
    <script src="GoogleCharts/Charts.js"></script>
    
    <!-- Initialization of the WebApp -->
    ...

Screenshots and example workspace

You can download a completely functional DataFlex 19.1 Workspace down here, unzip, register in DataFlex 19.1, let the Studio create the javascript engine folders and run:

File:GoogleChartsDemo-20200326.zip

External links

• Google Charts official documentation
• Forum question that triggered this article