update_shopping_product.py

product_id="online:en:US:XX-XXXXX-XXXX-XX"
merchant_id = XXXXXXX

product = service.products().get(
    merchantId=merchant_id, productId=product_id).execute()

#partial example product result
"""{'adwordsRedirect': 'https://www.website.com/product/product_url?code=XXX',
 'ageGroup': 'adult',
 'availability': 'in stock',
 'brand': 'XXXXX',
 'channel': 'online',
 'color': 'Black',
 'condition': 'new',
 'contentLanguage': 'en',
 ...
 }"""

print(product["title"]) # output -> 'XXX Custom XXX XXXXX XXX XXX XXXXX XXX XXX XXXX'

#now let's prepare the change
product["title"] = 'XXX Personalized XXX XXXXX XXX XXX XXXXX XXX XXX XXXX'

#this line performs the update
request = service.products().insert(merchantId=merchant_id, body=product)
result = request.execute()

print(result["title"]) # output -> XXX Personalized XXX XXXXX XXX XXX XXXXX XXX XXX XXXX'

#the product was updated in Google Shopping programatically
#you can use the API explorer to confirm