Dynamic template support

[devchas]

Fixes #260

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation about the functionality in the appropriate .md file
• I have added in line documentation to the code I modified

Short description of what this PR does:

• Add dynamic template support for Go library
• Add helper method for dynamic template data
• Add dynamic template example in examples/helpers/mail/example.go (this had to be done in a separate function because dynamic template data and substitutions may not be used in the same API call
• Add documentation and examples in USE_CASES.md

[SendGridDX]

All committers have signed the CLA.

[thinkingserious]

In our UI, we are calling these Transactional Templates and the previous Transactional Templates are now called Legacy Templates.

[codecov]

Codecov Report

Merging #263 into master will increase coverage by 0.19%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #263      +/-   ##
==========================================
+ Coverage   70.75%   70.95%   +0.19%     
==========================================
  Files           3        3              
  Lines         448      451       +3     
==========================================
+ Hits          317      320       +3     
  Misses        127      127              
  Partials        4        4

Impacted Files	Coverage Δ
helpers/mail/mail_v3.go	98.11% <100%> (+0.02%)	⬆️

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[Revinand]

Any update on this? When this PR will be merged?

[thinkingserious]

Hello @Revinand,

We just launched support PHP and Python, next is C#, Java, Node.js and then Go. I can't give you a firm timeline, but it's coming soon. It's a high priority for our team.

My apologies for the delay.

With Best Regards,

Elmer

[ivannikolic]

Hi @thinkingserious,

We created some dynamic templates in SendGrid and now we depend on this pull request to be able to use them with the SendGrid's Go library.
I understand that you can't give the firm timeline, but can you just tell me the rough estimation when can we expect the feature to be available? Is it a matter of days, weeks, months?

Ivan Nikolic
ricardo.ch

[seangransee]

@ivannikolic In the meantime, I'm just using github.com/devchas/sendgrid-go/helpers/mail checked out to branch dynamic-template-support.

[thinkingserious]

Hi @ivannikolic,

I would say it's a matter of weeks. We have C# (in progress), Java, Node.js (just needs documentation update) to go before we tackle this one.

With Best Regards,

Elmer

[devchas]

Hi @ivannikolic - in addition to the suggestion @seangransee made, you can always create the request body of the API call without the helper method, passing a JSON string. The dynamic templates will still work.

[ivannikolic]

@seangransee @thinkingserious @devchas Thank you all for the ideas and helpful information!

[kayue]

For those who cannot wait for the PR to merge, here is a small method that can inject personalization data to a mail object, and return json

func getMailRequestBody(mail *mail.SGMailV3) ([]byte) {
    jsonData := gin.H{}
    marshal, _ := json.Marshal(mail)
    json.Unmarshal(marshal, &jsonData)
    personalizations := jsonData["personalizations"].([]interface{})

    for _, personalization := range personalizations {
        p := personalization.(map[string]interface {})
        p["dynamic_template_data"] = gin.H{
            "foo": "bar",
        }
    }

    body, _ := json.Marshal(jsonData)

    return body
}

[thinkingserious]

Hello @devchas,

Thanks again for the PR!

We appreciate your contribution and look forward to continued collaboration. Thanks!

Team SendGrid DX