Insert R object into json string - r

Question

I am sending an email from a Shiny app via the SendGrid API using the HTTR package (using POST function with json encoding). I need to pass an R object in between the json quotes that are used to define the text body of the email:
I have tried to convert the R object to json as follows:
client_id<- "f432jj"
email_text<- paste("Below is your unique key:", client_id, "Please copy
your key to the clipboard, then click 'Begin'")
email_text<- jsonlite::toJSON(email_text)
Here is the json code into which I need to insert the email_text object.
body = '{"from": {"email":"xxx#gmail.com"},
"personalizations": [{"to": [{"email":"zzz#gmail.com"}],
"dynamic_template_data":{
"header":"A measure is ready to be completed",
"text": email_text,
"c2a_button":"Begin",
"c2a_link":"yyy#gmail.com"}}],
"template_id":"e-98766334"}'
When trying to pass in the email_text object as above and send the email, I get:
HTTP/1.1 400 Bad Request
I think this means the syntax is wrong.
Any help much appreciated.

Answer 1

Normally you wouldn't build your body JSON data as a string. You could build the list that represents the data and then let jsonlite turn it into a JSON string for you. Your example might look something like this
client_id<- "f432jj"
email_text<- paste("Below is your unique key:", client_id, "Please copy
your key to the clipboard, then click 'Begin'")
body <- list(
from = list(email="xxx#gmail.com"),
personalizations = list(list(to=list(list(email="zzz#gmail.com")))),
dynamic_template_data = list(
header="A measure is ready to be completed",
text = email_text,
c2a_button = "Begin",
c2a_link = "yyy#gmail.com"
),
template_id = "e-98766334"
)
jsonlite::toJSON(body,auto_unbox=TRUE)