Is there any Solution to download attachment from gmail in WSO2 ESB / WSO2 EI? - gmail-api

Question

I am working on wso2 esb since last 6 months. I want to download attachment from gmail in wso2 esb/ei and save them into local folder.Google it and get solution only for sending attachment using gmail connector, not downloading attachment.
Note: Already seen,but can't able to get solution by referring the following link-
WSO2 esb get attach files from email
Code:
ProxyService
<proxy name="GmailConfigAttachment-TaskProxy" startOnLoad="true"
transports="http https" xmlns="http://ws.apache.org/ns/synapse">
<target>
<inSequence>
<log level="custom">
<property name="Log Text"
value="Inside GmailConfigAttachment-TaskProxy Service"></property>
</log>
<property name="FORCE_SC_ACCEPTED" scope="axis2" type="STRING"
value="true" />
<property description="serviceName" name="serviceName"
scope="operation" type="STRING"
value="TaskScheduler_ASG_Read_Email_Body_Dummy_Service" />
<property description="messageId" expression="get-property('MessageID')"
name="messageId" scope="operation" type="STRING" />
<sequence key="Load_Gmail_Configuration" />
<gmail.init>
<userId>{$ctx:userId}</userId>
<accessToken>{$ctx:accessToken}</accessToken>
<apiUrl>{$ctx:apiUrl}</apiUrl>
<clientId>{$ctx:clientId}</clientId>
<clientSecret>{$ctx:clientSecret}</clientSecret>
<refreshToken>{$ctx:refreshToken}</refreshToken>
<accessTokenRegistryPath>{$ctx:registryPath}</accessTokenRegistryPath>
</gmail.init>
<gmail.listAllMails>
<labelIds>INBOX</labelIds>
<q>is:unread</q>
</gmail.listAllMails>
<log level="full" />
<iterate description="MailIterator" expression="//jsonObject/messages" sequential="true" id="listUnread">
<target>
<sequence>
<log description="Iterate Logger" level="custom" separator=",**, ">
<property expression="fn:concat('GmailConfigAttachment-TaskProxy_Service ESB-MessageId:',get-property('operation','messageId'))" name="LogText" />
<property expression="//id/text()" name="Gmail-MessageId" />
</log>
<property description="emailMsgId" expression="//id/text()" name="emailMsgId" scope="default" type="STRING" />
<property description="emailSubject" expression="//headers/name[text()='Subject']/../value/text()" name="emailSubject" scope="default" type="STRING"/>
<property description="emailDate" expression="//headers/name[text()='Date']/../value/text()" name="emailDate" scope="operation" type="STRING"/>
<property description="toAddress" expression="//headers/name[text()='To']/../value/text()" name="toAddress" scope="operation" type="STRING"/>
<header expression="fn:concat('Bearer ', $ctx:uri.var.gmail.accessToken)" name="Authorization" scope="transport" />
<gmail.readMail>
<id>{$ctx:emailMsgId}</id>
</gmail.readMail>
<payloadFactory media-type="xml">
<format>
<htmlProcessEmailBody xmlns="">
<emailMessageId>$1</emailMessageId>
<emailSubject>$2</emailSubject>
<emailBody>$3</emailBody>
</htmlProcessEmailBody>
</format>
<args>
<arg evaluator="xml" expression="get-property('emailMsgId')"/>
<arg evaluator="xml" expression="get-property('emailSubject')"/>
<arg evaluator="xml" expression="//payload"/>
</args>
</payloadFactory>
<log level="custom">
<property description="emailMsgId" expression="get-property('emailMsgId')" name="emailMsgId" scope="default" type="STRING" />
<property description="emailSubject" expression="//headers/name[text()='Subject']/../value/text()" name="emailSubject" scope="default" type="STRING"/>
<property description="emailDate" expression="//headers/name[text()='Date']/../value/text()" name="emailDate" scope="default" type="STRING"/>
<property description="toAddress" expression="//headers/name[text()='To']/../value/text()" name="toAddress" scope="default" type="STRING"/>
</log>
<!-- here i need further process to download attachment from gmail -->
</sequence>
</target>
</iterate>
</inSequence>
<outSequence />
<faultSequence />
</target>
Output of ESB
So Can anyone help me to provide solution?
Awaiting for your response.
Thank you.

Answer 1

Finally i found the solution for my question.
Idea :
Iterating each parts then getting email attachment id which will be passed to gmail api in order to get base64 encoded format.
Code snippet:
<iterate continueParent="true" description="MailIterator" expression="//parts" id="listUnread" sequential="true">
<target>
<sequence>
<property expression="//filename[text()!=' ']" name="AttachedFileName" scope="default" type="STRING"/>
<property expression="substring-after(get-property('AttachedFileName'),'.')" name="Attachmentextension" scope="default" type="STRING"/>
<filter description="check emailSubject" regex="jpg|jpeg|png|gif|webp|tiff|tif|psd|raw|bmp|dib|heif|heic|indd|ind|jp2" source="lower-case(get-property('Attachmentextension'))">
<then>
<property description="emailAttachmentId" expression="//attachmentId/text()" name="uri.var.attachmentId" scope="default" type="STRING"/>
<log level="custom">
<property expression="get-property('AttachedFileName')" name="=====ValidAttachmentFileName===="/>
<property expression="get-property('uri.var.attachmentId')" name="====emailAttachmentId====="/>
</log>
<header expression="fn:concat('Bearer ', $ctx:uri.var.gmail.accessToken)" name="Authorization" scope="transport"/>
<call>
<endpoint>
<http method="get" uri-template="{+uri.var.gmail.apiUrl}/{+uri.var.gmail.apiVersion}/users/{+uri.var.gmail.userId}/messages/{+uri.var.id}/attachments/{+uri.var.attachmentId}"/>
</endpoint>
</call>
<property description="emailAttachment" expression="//data/text()" name="emailAttachment" scope="default" type="STRING"/>
<!-- ==========Script for Base64 url to Base64 Encoding Format ========== -->
<script language="js"><![CDATA[var log=mc.getServiceLog();
var emailAttachment = mc.getProperty('emailAttachment');
emailAttachment=emailAttachment.replaceAll("_","/").replaceAll("-","+");
mc.setProperty("modifiedemailAttachment",emailAttachment)]]></script>
<log level="custom">
<property expression="get-property('modifiedemailAttachment')" name="========modifiedemailAttachment========"/>
</log>