Custom Message or paragraph from the using Jquery datatable and pdf export - pdf

Question

I'm using the pdf button from jquery datatables which is essentially the pdfmake library. The problem that I'm having is that I would like to add an additional paragraph right above my table when the user clicks the button to export the table. I have tried using the "message" parameter but for the life of me I cannot retrieve additional information right before the pdf will download. I tried doing this.
buttons: [
{
extend: 'pdfHtml5',
orientation: 'landscape',
pageSize: 'LEGAL',
title: 'Entry',
header:true,
message:function() { $("#HeaderDesc").text()}
}
]
But I have been unsuccessful in my attempts. Does anyone have any ideas on how to accomplish this?

Answer 1

There is another easy solution to this.
I accomplished this by using splice property. You can do like this inside customize function.
doc.content.splice(0, 1, {
text: [
{ text: 'I am loving dataTable and PdfMake \n',bold:true,fontSize:15 },
{ text: 'You can control everything.',italics:true,fontSize:12 }
],
margin: [0, 0, 0, 12],
alignment: 'center'
});
This will splice at the first position [0 index] as well as replace 1 value with the above content.
Happy coding!!!!

Answer 2

You cannot. The config literal for the button is read once, and message does not support function type.
However, you can change the message in the not so well documented customize() callback. This is called just before dataTables pass the generated document to pdfmake. If you have defined a message, then there will exists message section(s) in the content nodes, and those nodes have a text attribute holding the actual message :
customize: function ( doc ) {
doc.content.forEach(function(content) {
if (content.style == 'message') {
content.text = 'this is a late created message'
}
})
}
As mentioned, you must define message before this will work. If you have not defined message, there will be no styles of type message you can manipulate. Your pdfhtml5 settings could look like this :
buttons: [
{
message: '__MESSAGE__',
extend: 'pdfHtml5',
orientation: 'landscape',
pageSize: 'LEGAL',
title: 'Entry',
header:true,
customize: function ( doc ) {
doc.content.forEach(function(content) {
if (content.style == 'message') {
content.text = $("#HeaderDesc").text()
}
})
}
}
]
demo -> https://jsfiddle.net/xx5f5z6x/