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This guide explains how to use the Google Docs API to perform a mail merge.
Introduction
A mail merge takes values from rows of a spreadsheet or another data source
and inserts them into a template document. This lets you create a single primary
document (the template) from which you can generate many similar documents, each
customized with the data being merged. The result isn't necessarily used for
mail or form letters, but can be for any purpose, such as generating a batch of
customer invoices.
Mail merge has been around for as long as there have been spreadsheets and word
processors, and is part of many business workflows today. The convention is to
organize the data as one record per row, with the columns representing fields in
the data, as shown in the following table:
Name
Address
Zone
1
UrbanPq
123 1st St.
West
2
Pawxana
456 2nd St.
South
The sample app on this page shows how you can use the Google Docs,
Sheets, and Drive APIs to abstract away the
details of how mail merges are performed, protecting users from implementation
concerns. More information on this Python sample can be found at the sample's
GitHub
repo.
Sample application
This sample app copies your primary template and then merges variables from your
designated data source into each of the copies. To try this sample app, first
set up your template:
Note the new file's document ID. For more information, see Document
ID.
Set the DOCS_FILE_ID variable to the document ID.
Replace the contact information with template placeholder variables that the
app will merge with the selected data.
Here's a sample letter
template
with placeholders that can be merged with real data from a source such as plain
text or Sheets. Here's what that template looks like:
Next, choose either plain text or Sheets as your data source
using the SOURCE variable. The sample defaults to plain text, meaning the
sample data uses the TEXT_SOURCE_DATA variable. To source data from
Sheets, update the SOURCE variable to 'sheets' and point it
to our sample
sheet
(or your own) by setting the SHEETS_FILE_ID variable.
Here's what the sheet looks like so you can see the format:
Try the app with our sample data, then adapt it to your data and use case. The
command-line application works like this:
Setup
Fetch the data from the data source
Loop through each row of data
Create a copy of the template
Merge the copy with the data
Output link to newly-merged document
All newly merged letters also show up in the user's My Drive. An
example of a merged letter looks something like this:
import time
import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
# Fill-in IDs of your Docs template & any Sheets data source
DOCS_FILE_ID = "195j9eDD3ccgjQRttHhJPymLJUCOUjs-jmwTrekvdjFE"
SHEETS_FILE_ID = "11pPEzi1vCMNbdpqaQx4N43rKmxvZlgEHE9GqpYoEsWw"
# authorization constants
SCOPES = ( # iterable or space-delimited string
"https://www.googleapis.com/auth/drive",
"https://www.googleapis.com/auth/documents",
"https://www.googleapis.com/auth/spreadsheets.readonly",
)
# application constants
SOURCES = ("text", "sheets")
SOURCE = "text" # Choose one of the data SOURCES
COLUMNS = ["to_name", "to_title", "to_company", "to_address"]
TEXT_SOURCE_DATA = (
(
"Ms. Lara Brown",
"Googler",
"Google NYC",
"111 8th Ave\nNew York, NY 10011-5201",
),
(
"Mr. Jeff Erson",
"Googler",
"Google NYC",
"76 9th Ave\nNew York, NY 10011-4962",
),
)
# fill-in your data to merge into document template variables
merge = {
# sender data
"my_name": "Ayme A. Coder",
"my_address": "1600 Amphitheatre Pkwy\nMountain View, CA 94043-1351",
"my_email": "http://google.com",
"my_phone": "+1-650-253-0000",
# - - - - - - - - - - - - - - - - - - - - - - - - - -
# recipient data (supplied by 'text' or 'sheets' data source)
"to_name": None,
"to_title": None,
"to_company": None,
"to_address": None,
# - - - - - - - - - - - - - - - - - - - - - - - - - -
"date": time.strftime("%Y %B %d"),
# - - - - - - - - - - - - - - - - - - - - - - - - - -
"body": (
"Google, headquartered in Mountain View, unveiled the new "
"Android phone at the Consumer Electronics Show. CEO Sundar "
"Pichai said in his keynote that users love their new phones."
),
}
creds, _ = google.auth.default()
# pylint: disable=maybe-no-member
# service endpoints to Google APIs
DRIVE = build("drive", "v2", credentials=creds)
DOCS = build("docs", "v1", credentials=creds)
SHEETS = build("sheets", "v4", credentials=creds)
def get_data(source):
"""Gets mail merge data from chosen data source."""
try:
if source not in {"sheets", "text"}:
raise ValueError(
f"ERROR: unsupported source {source}; choose from {SOURCES}"
)
return SAFE_DISPATCH[source]()
except HttpError as error:
print(f"An error occurred: {error}")
return error
def _get_text_data():
"""(private) Returns plain text data; can alter to read from CSV file."""
return TEXT_SOURCE_DATA
def _get_sheets_data(service=SHEETS):
"""(private) Returns data from Google Sheets source. It gets all rows of
'Sheet1' (the default Sheet in a new spreadsheet), but drops the first
(header) row. Use any desired data range (in standard A1 notation).
"""
return (
service.spreadsheets()
.values()
.get(spreadsheetId=SHEETS_FILE_ID, range="Sheet1")
.execute()
.get("values")[1:]
)
# skip header row
# data source dispatch table [better alternative vs. eval()]
SAFE_DISPATCH = {k: globals().get(f"_get_{k}_data") for k in SOURCES}
def _copy_template(tmpl_id, source, service):
"""(private) Copies letter template document using Drive API then
returns file ID of (new) copy.
"""
try:
body = {"name": f"Merged form letter ({source})"}
return (
service.files()
.copy(body=body, fileId=tmpl_id, fields="id")
.execute()
.get("id")
)
except HttpError as error:
print(f"An error occurred: {error}")
return error
def merge_template(tmpl_id, source, service):
"""Copies template document and merges data into newly-minted copy then
returns its file ID.
"""
try:
# copy template and set context data struct for merging template values
copy_id = _copy_template(tmpl_id, source, service)
context = merge.iteritems() if hasattr({}, "iteritems") else merge.items()
# "search & replace" API requests for mail merge substitutions
reqs = [
{
"replaceAllText": {
"containsText": {
"text": "{{%s}}" % key.upper(), # {{VARS}} are uppercase
"matchCase": True,
},
"replaceText": value,
}
}
for key, value in context
]
# send requests to Docs API to do actual merge
DOCS.documents().batchUpdate(
body={"requests": reqs}, documentId=copy_id, fields=""
).execute()
return copy_id
except HttpError as error:
print(f"An error occurred: {error}")
return error
if __name__ == "__main__":
# get row data, then loop through & process each form letter
data = get_data(SOURCE) # get data from data source
for i, row in enumerate(data):
merge.update(dict(zip(COLUMNS, row)))
print(
"Merged letter %d: docs.google.com/document/d/%s/edit"
% (i + 1, merge_template(DOCS_FILE_ID, SOURCE, DRIVE))
)
For more information, see the README file and the full application source code
at the sample app's GitHub
repo.
