Short answer
At this time, variables is not a built-in feature of Google Docs and Google Apps Script, the platform to extend Google Docs, does not include a class or method to handle them.
Alternatives
Alternative 1
One alternative is use a text pattern but you should be sure that it will match only the date that you want to update.
Alternative 2
Another alternative is to use the class NamedRange but bear in mind that
- moving the range will make that it lose its name1.
- replacing text in a named range with multiple elements only works the first time2.
Code:
The following code, intended to be used in a script bound to a Google Document, has two main functions:
- Insert today's date
- Update today's date
For debugging purposes are being used
- date and time, instead of date only.
- custom menus to trigger the main functions.
"Known-issues": The update function replaces the whole paragraph.
To test the code, copy it, then go to your Google Docs, create a new document, click on Tools > Script Editor, select Blank Project, paste the code, save the project, assign a name, run on time to authorize the app, close your doc and open again. A new menu called "Utilities" will be displayed. From there you can call the main functions.
function onOpen() {
// Add a menu with some items, some separators, and a sub-menu.
DocumentApp.getUi().createMenu('Utilities')
.addItem('Insert Today\'s Date', 'insertTodayAtCursor')
.addItem('Update Today\'s Date', 'setTodayNamedRange')
.addToUi();
}
function todayDate(){
return Utilities.formatDate(new Date(), "GMT-5", "yyyy-MM-dd'T'HH:mm:ss'Z'"); // "yyyy-MM-dd"
}
/**
* Inserts the today's date at the current cursor location and create a NamedRange.
*/
function insertTodayAtCursor() {
var str = 'testToday';
var doc = DocumentApp.getActiveDocument();
var cursor = doc.getCursor();
if (cursor) {
// Attempt to insert today's date at the cursor position. If insertion returns null,
// then the cursor's containing element doesn't allow text insertions.
var date = todayDate();
var element = cursor.insertText(date);
if (element) {
var rangeBuilder = doc.newRange();
rangeBuilder.addElement(element);
return doc.addNamedRange(str, rangeBuilder.build());
} else {
DocumentApp.getUi().alert('Cannot insert text at this cursor location.');
}
} else {
DocumentApp.getUi().alert('Cannot find a cursor in the document.');
}
}
function setTodayNamedRange(){
var str = 'testToday';
var doc = DocumentApp.getActiveDocument();
// Retrieve the named range
var namedRanges = doc.getNamedRanges();
var newRange = doc.newRange();
var date = todayDate();
for(var i=0; i<namedRanges.length; i++){
if(namedRanges[i].getName() == str){
var rangeElement = namedRanges[i].getRange().getRangeElements();
for (var j=0; j<rangeElement.length; j++){
var element = rangeElement[j].getElement().asText().editAsText().setText(date);
newRange.addElement(element);
}
}
}
doc.addNamedRange(str, newRange.build());
}
Below there are some items of different kind (questions, specifications, etc.) that could serve to get inspiration or point to the "right direction" to find a "solution"
Footnotes