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In this tutorial, we will following the guideline of developing a plugin to develop our Download PDF Datalist Action plugin. Please also refer to the very first tutorial How to develop a Bean Shell Hash Variable for more details steps.

1. What is the problem?

We need to provide a PDF download feature when user click on a link/button on a datalist. The downloaded PDF file should be a form with data populated.

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  1. Form ID : The form that will be used to generate the PDF file.
  2. Record ID Column : Use the id of the datalist row or a column value to load the record.
  3. File Name : File name of the the generated PDF file.
  4. Formatting options : Options to format and customise the PDF output. 

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Create a "DownloadPdfDatalistAction" class under "org.joget.tutorial" package. Then, extend the class with org.joget.apps.datalist.model.DataListActionDefault abstract class. Please refer to Datalist Action Plugin.

b. Implement all the abstract methods

As usual, we have to implement all the abstract methods. We will using AppPluginUtil.getMessage method to support i18n and using constant variable MESSAGE_PATH for message resource bundle directory.

Code Block
languagejava
titleImplementation of all basic abstract methods
collapsetrue
package org.joget.tutorial;
 
import org.joget.apps.app.service.AppPluginUtil;
import org.joget.apps.datalist.model.DataListActionDefault;
 
public class DownloadPdfDatalistAction extends DataListActionDefault {
    
    private final static String MESSAGE_PATH = "messages/DownloadPdfDatalistAction";
 
    public String getName() {
        return "Download PDF Datalist Action";
    }
    public String getVersion() {
        return "5.0.0";
    }
    
    public String getClassName() {
        return getClass().getName();
    }
    
    public String getLabel() {
        //support i18n
        return AppPluginUtil.getMessage("org.joget.tutorial.DownloadPdfDatalistAction.pluginLabel", getClassName(), MESSAGE_PATH);
    }
    
    public String getDescription() {
        //support i18n
        return AppPluginUtil.getMessage("org.joget.tutorial.DownloadPdfDatalistAction.pluginDesc", getClassName(), MESSAGE_PATH);
    }
 
    public String getPropertyOptions() {
        return AppUtil.readPluginResource(getClassName(), "/properties/downloadPdfDatalistAction.json", null, true, MESSAGE_PATH);
    }
 
    public String getLinkLabel() {
        return getPropertyString("label"); //get label from configured properties options
    }
 
    public String getHref() {
        return getPropertyString("href"); //Let system to handle to post to the same page
    }
 
    public String getTarget() {
        return "post";
    }
 
    public String getHrefParam() {
        return getPropertyString("hrefParam");  //Let system to set the parameter to the checkbox name
    }
 
    public String getHrefColumn() {
        String recordIdColumn = getPropertyString("recordIdColumn"); //get column id from configured properties options
        if ("id".equalsIgnoreCase(recordIdColumn) || recordIdColumn.isEmpty()) {
            return getPropertyString("hrefColumn"); //Let system to set the primary key column of the binder
        } else {
            return recordIdColumn;
        }
    }
 
    public String getConfirmation() {
        return getPropertyString("confirmation"); //get confirmation from configured properties options
    }
 
    public DataListActionResult executeAction(DataList dataList, String[] rowKeys) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
}

Then, we have to do a UI for admin user to provide inputs for our plugin. In getPropertyOptions method, we already specify our Plugin Properties Options definition file is locate at "/properties/downloadPdfDatalistAction.json". Let us create a directory "resources/properties" under "download_pdf_datalist_action/src/main" directory. After create the directory, create a file named "downloadPdfDatalistAction.json" in the "properties" folder.

In the properties definition options file, we will need to provide options as below. Please note that we can use "@@message.key@@" syntax to support i18n in our properties options.

Code Block
languagejs
[{
    title : '@@datalist.downloadPdf.config@@',
    properties : [{
        name : 'label',
        label : '@@datalist.downloadPdf.label@@',
        type : 'textfield',
        value : '@@datalist.downloadPdf.download@@'
    },
    {
        name : 'formDefId',
        label : '@@datalist.downloadPdf.form@@',
        type : 'selectbox',
        options_ajax : '[CONTEXT_PATH]/web/json/console/app[APP_PATH]/forms/options',
        required : 'True'
    },
    {
        name : 'recordIdColumn',
        label : '@@datalist.downloadPdf.recordIdColumn@@',
        description : '@@datalist.downloadPdf.recordIdColumn.desc@@',
        type : 'textfield'
    },
    {
        name : 'confirmation',
        label : '@@datalist.downloadPdf.confirmationMessage@@',
        type : 'textfield'
    }]
},
{
    title : '@@datalist.downloadPdf.advanced@@',
    properties : [{
        name : 'formatting',
        label : '@@datalist.downloadPdf.formatting@@',
        type : 'codeeditor',
        mode : 'css'
    },
    {
        name : 'headerHtml',
        label : '@@datalist.downloadPdf.headerHtml@@',
        type : 'codeeditor',
        mode : 'html'
    },
    {
        name : 'repeatHeader',
        label : '@@datalist.downloadPdf.repeatHeader@@',
        type : 'checkbox',
        options : [{
            value : 'true',
            label : ''
        }]
    },
    {
        name : 'footerHtml',
        label : '@@datalist.downloadPdf.footerHtml@@',
        type : 'codeeditor',
        mode : 'html'
    },
    {
        name : 'repeatFooter',
        label : '@@datalist.downloadPdf.repeatFooter@@',
        type : 'checkbox',
        options : [{
            value : 'true',
            label : ''
        }]
    },
    {
        name : 'hideEmptyValueField',
        label : '@@datalist.downloadPdf.hideEmptyValueField@@',
        type : 'checkbox',
        options : [{
            value : 'true',
            label : ''
        }]
    },
    {
        name : 'showNotSelectedOptions',
        label : '@@datalist.downloadPdf.showNotSelectedOptions@@',
        type : 'checkbox',
        options : [{
            value : 'true',
            label : ''
        }]
    }]
}]

After done the properties option to collect input, we can work on the main method of the plugin which is executeAction method.

Code Block
languagejava
    public DataListActionResult executeAction(DataList dataList, String[] rowKeys) {
        // only allow POST
        HttpServletRequest request = WorkflowUtil.getHttpServletRequest();
        if (request != null && !"POST".equalsIgnoreCase(request.getMethod())) {
            return null;
        }
        
        // check for submited rows
        if (rowKeys != null && rowKeys.length > 0) {
            try {
                //get the HTTP Response
                HttpServletResponse response = WorkflowUtil.getHttpServletResponse();
                if (rowKeys.length == 1) {
                    //generate a pdf for download
                    singlePdf(request, response, rowKeys[0]);
                } else {
                    //generate a zip of all pdfs
                    multiplePdfs(request, response, rowKeys);
                }
            } catch (Exception e) {
                LogUtil.error(getClassName(), e, "Fail to generate PDF for " + ArrayUtils.toString(rowKeys));
            }
        }
        
        //return null to do nothing
        return null;
    }
    
    /**
     * Handles for single pdf file
     * @param request
     * @param response
     * @param rowKey
     * @throws IOException 
     * @throws javax.servlet.ServletException 
     */
    protected void singlePdf(HttpServletRequest request, HttpServletResponse response, String rowKey) throws IOException, ServletException {
        byte[] pdf = getPdf(rowKey);
        writeResponse(request, response, pdf, rowKey+".pdf", "application/pdf");
    }
    
    /**
     * Handles for multiple files download. Put all pdfs in zip.
     * @param request
     * @param response
     * @param rowKeys 
     * @throws java.io.IOException 
     * @throws javax.servlet.ServletException 
     */
    protected void multiplePdfs(HttpServletRequest request, HttpServletResponse response, String[] rowKeys) throws IOException, ServletException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ZipOutputStream zip = new ZipOutputStream(baos);
        
        try {
            //create pdf and put in zip
            for (String id : rowKeys) {
                byte[] pdf = getPdf(id);
                zip.putNextEntry(new ZipEntry(id+".pdf"));
                zip.write(pdf);
                zip.closeEntry();
            }
 
            zip.finish();
            writeResponse(request, response, baos.toByteArray(), getLinkLabel() +".zip", "application/zip");
        } finally {
            baos.close();
            zip.flush();
        }
    }
    
    /**
     * Generate PDF using FormPdfUtil
     * @param id
     * @return 
     */
    protected byte[] getPdf(String id) {
        AppDefinition appDef = AppUtil.getCurrentAppDefinition();
        String formDefId = getPropertyString("formDefId");
 
        Boolean hideEmptyValueField = null;
        if (getPropertyString("hideEmptyValueField").equals("true")) {
            hideEmptyValueField = true;
        }
        Boolean showNotSelectedOptions = null;
        if (getPropertyString("showNotSelectedOptions").equals("true")) {
            showNotSelectedOptions = true;
        }
        Boolean repeatHeader = null;
        if ("true".equals(getPropertyString("repeatHeader"))) {
            repeatHeader = true;
        }
        Boolean repeatFooter = null;
        if ("true".equals(getPropertyString("repeatFooter"))) {    
            repeatFooter = true;
        }
        String css = null;
        if (!getPropertyString("formatting").isEmpty()) {
            css = getPropertyString("formatting");
        }
        String header = null; 
        if (!getPropertyString("headerHtml").isEmpty()) {
            header = getPropertyString("headerHtml");
            header = AppUtil.processHashVariable(header, null, null, null);
        }
        String footer = null; 
        if (!getPropertyString("footerHtml").isEmpty()) {
            footer = getPropertyString("footerHtml");
            footer = AppUtil.processHashVariable(footer, null, null, null);
        }
        
        return FormPdfUtil.createPdf(formDefId, id, appDef, null, hideEmptyValueField, header, footer, css, showNotSelectedOptions, repeatHeader, repeatFooter);
    }
    
    /**
     * Write to response for download
     * @param response
     * @param bytes
     * @param filename
     * @param contentType
     * @throws IOException 
     */
    protected void writeResponse(HttpServletRequest request, HttpServletResponse response, byte[] bytes, String filename, String contentType) throws IOException, ServletException {
        OutputStream out = response.getOutputStream();
        try {
            String name = URLEncoder.encode(filename, "UTF8").replaceAll("\\+", "%20");
            response.setHeader("Content-Disposition", "attachment; filename="+name+"; filename*=UTF-8''" + name);
            response.setContentType(contentType+"; charset=UTF-8");
            
            if (bytes.length > 0) {
                response.setContentLength(bytes.length);
                out.write(bytes);
            }
        } finally {
            out.flush();
            out.close();
            
            //simply foward to a 
            request.getRequestDispatcher(filename).forward(request, response);
        }
    }

c. Manage the dependency libraries of your plugin

Our plugin is using javax.servlet.http.HttpServletRequest and javax.servlet.http.HttpServletResponse class, so we will need to add jsp-api library to our POM file.

Code Block
languagexml
<!-- Change plugin specific dependencies here -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jsp-api</artifactId>
    <version>2.0</version>
</dependency>
<!-- End change plugin specific dependencies here -->

d. Make your plugin internationalization (i18n) ready

We are using i18n message key in getLabel and getDescription method. We also used i18n message key in our properties options definition as well. So, we will need to create a message resource bundle properties file for our plugin.

Create directory "resources/messages" under "download_pdf_datalist_action/src/main" directory. Then, create a "DownloadPdfDatalistAction.properties" file in the folder. In the properties file, let add all the message keys and its label as below.

Code Block
org.joget.tutorial.DownloadPdfDatalistAction.pluginLabel=Download PDF
org.joget.tutorial.DownloadPdfDatalistAction.pluginDesc=Support to download form PDF from datalist
datalist.downloadPdf.download=Download
datalist.downloadPdf.config=Configure Download PDF Action
datalist.downloadPdf.label=Label
datalist.downloadPdf.form=Form
datalist.downloadPdf.recordIdColumn=Record Id Column
datalist.downloadPdf.recordIdColumn.desc=Default to the primary key of the configured binder
datalist.downloadPdf.confirmationMessage=Confirmation Message
datalist.downloadPdf.hideEmptyValueField=Hide field that without value
datalist.downloadPdf.showNotSelectedOptions=Show unselected options for multi options field
datalist.downloadPdf.advanced=Advanced
datalist.downloadPdf.formatting=Formatting (CSS)
datalist.downloadPdf.headerHtml=Header (HTML)
datalist.downloadPdf.repeatHeader=Repeat header on every page?
datalist.downloadPdf.footerHtml=Footer (HTML)
datalist.downloadPdf.repeatFooter=Repeat footer on every page?

e. Register your plugin to Felix Framework

We will have to register our plugin class in Activator class (Auto generated in the same class package) to tell Felix Framework that this is a plugin.

Code Block
languagejava
    public void start(BundleContext context) {
        registrationList = new ArrayList<ServiceRegistration>();
        //Register plugin here
        registrationList.add(context.registerService(DownloadPdfDatalistAction.class.getName(), new DownloadPdfDatalistAction(), null));
    }

 

f. Build it and testing

 

Let build our plugin. Once the building process is done, we will found a "download_pdf_datalist_action-5.0.0.jar" file is created under "download_pdf_datalist_action/target" directory.

Then, let upload the plugin jar to Manage Plugins. After upload the jar file, double check the plugin is uploaded and activated correctly.

Image Added

Then, Let try it in one of the datalist. You can find our new plugin is shown under "Actions" in Datalist Builder.

Image Added

Once we dragged and dropped the "Download PDF" action into the datalist builder canvas, we can edit the action. The following configuration page will shown based on our properties option definition.

Image Added Image Added

Let add the "Download PDF" action as row action and also the whole list action for testing. We can see the "Download" button shown correctly in userview as image below.

Image Added

When row action is clicked, a pdf is downloaded.

Image Added

When the whole list action is clicked, a zip is downloaded.

Image Added

8. Take a step further, share it or sell it

You can download the source code from download_pdf_datalist_action.zip.

To download the ready-to-use plugin jar, please find it in http://marketplace.joget.org/.