How do I calculate limit of Substitutions per personalization block in SendGrid? - sendgrid

Question

I'm trying to send an email with SendGrid using a transaction template, and see a problem with substitution limited.
Substitutions are limited to 10000 bytes per personalization block.
SendGrid Docs
I will resolved this problem by get the template from SendGrid and replace all placeholders inside it. But I need to check when I can do it, I think will check limited of substitutions and I don't know How SendGrid calculate it? maybe length of all string in substitutions?
Any help?
Thanks!

Answer 1

I resolved my problem and share the solution for the people who care ;)
Solution:
You need to optimize Substitutions by using it together with Sections
/**
* When you have the $variables too big, SendGrid will reject the message because
* SendGrid's Substitution is limited(10000 bytes)
*
* Before that, the format of substitution as below:
*
* {
* "to": [
* "example#example.com"
* ],
* "sub": {
* "%FirstName%": "This string maybe too long",
* "%LastName%": "This string maybe too long",
* ....
* ....
* more and limited
* }
* }
*
* To resolved this problem we will use the Section with Substitution as below:
*
* {
* "to": [
* "example#example.com"
* ],
* "sub": {
* "%FirstName%": "%FirstName%",
* "%LastName%": "%LastName%",
* ....
* ....
* more and more
* },
* "section": {
* "%FirstName%": "This string maybe too long",
* "%LastName%": "This string maybe too long",
* ....
* ....
* }
* }
*
* We will optimize the strings in Substitutions and let Section in SendGrid to contain that strings.
*/

Answer 2

As per sendgrid documentation they are going to remove support for Section. As they says Substitution is alternative for Section. Do you have any other alternative for large content (> 10000 bytes).