Accessing values through bracket notation with a variable in bracket after looping through struct for field names - go

Question

I have 2 JSON files one containing users, and another containing email templates
I'm looping through the code in the email templates, and when there is a key as a value, like this:
"keyToFind": "Username"
Then I want to get the value for Username in the other JSON file:
"Username": "ssmith"
KeyToFind can be a few different things, like Password or Group and I want to avoid writing a specific if statement
I'm trying to do this in my loop but it appears that I can't use a variable in bracket notation
for _, emailElements := range emailTemplates.EmailSpecification {
for _, fieldName := range structs.Names(&User{}) {
if emailElements.KeyToFind == fieldName {
EmailBody.WriteString(user[fieldName])
}
}
What the above is trying to do is loop through the elements in the email template, and then the fields in the Users struct; where an emailElement in the template JSON file of type KeyToFind is gotten, and this is the same as a field name in the struct; look up the user value for the KeyToFind
I could do this in Python without a problem
How can I rewrite line 4 to work in Go? --> user[FieldName]
The error I get is:
user[fieldName] (type User does not support indexing)
But if I write line 4 again to this:
user.Username
It will work fine, but that's obviously only for usernames, they could be Password or Group for the value in KeyToFind
Here are the JSON files:
Email template:
"emailName": "customer",
"emailSpecification": [
{
"emailSubject": "Hi"
},
{
"text": "Username: "
},
{
"keyToFind": "Username"
}
]
I want to get the value of KeyToFind and search the properties in the User file and return the value from that property
User file:
[
{
"UserType": "customer",
"Username": "ssmith",
"Password": "sophie"
}
]

Answer 1

I got it by converting the User struct to a map, once it's a map you can use the bracket notation with dot notation inside
In my context, I then had to convert to a string to pass into WriteString function that buffer needs
Here is the final version:
for _, emailElements := range emailTemplates.EmailSpecification {
for _, fieldName := range structs.Names(&User{}) {
if emailElements.KeyToFind == fieldName {
EmailBody.WriteString(structs.Map(user)[emailElements.KeyToFind].(string))
}
}
}
It's using the package:
"github.com/fatih/structs"