CODEWITHSUNDEEP
gotemplates
Tony
Tony

Reputation: 23

Ignore sections of a template if there is no value in Go

I'm working on a personal project to learn some more Go and hitting a snag (or potentially going about this all wrong too so there is that).

A little background first: I'm working on a simple web app with some form fields to do some basic network tests like curl, netcat, and traceroute. I was looking to use WASM so that I could just modify the DOM with results from the Go app, but I believe due to there being a lot of syscalls, the WASM architecture doesnt support them and I couldnt compile it after a certain point or when it did it was failing anytime I ventured into some of the network pkgs. I couldn't really find another way to use javascript without abandoning Go, so I decided to go with templates.

When a form is submitted it loads a results.html that is identical to the index.html except some Go templating to print the results of the network tests. It works great has a "meh" kinda of way to simulate JS modifications and allow you to do more tests without leaving the page BUT since there are three different network tests, and only one running at one time, I get errors when it can't fill ALL the templates.

So for example

  <section id="curlOutput">
    <p><strong>Executed curl to {{.URL}}</strong></p>
    <p>{{.Protocol}}</p>
    <p>{{.Status}}</p>
    <p>{{.ContentLength}}</p>
    {{range $key, $val := .Headers}}
    <p><strong>{{$key}}:</strong> {{$val}}</p>
    {{end}}
    <br/>
  </section>

  <section id="ncOutput">
    <p><strong>Executed netcat to {{.Host}}</strong></p>
    <p>{{.Result}}</p>
  </section>

The issue i hit is if I want to test Netcat, Go throws errors because it can't fill the earlier templates like for curl and such. So is there a way to define in the templates that if the value doesnt exist, just continue and leave it blank? Or does every single template have to be defined and filled? Perhaps defining defaults in the templates to be empty strings somehow? Is there a better way to go about this in general?

Sorry for the length, but i felt some background would help, thanks!

Upvotes: 0

Views: 1846

Answers (1)

mkopriva
mkopriva

Reputation: 38303

You can use a data struct better suited for the task and the with template action.

type Results struct {
    CURLOutput *CURLOutput
    NCOutput   *NCOutput
}

type CURLOutput struct {
    URL           string
    Protocol      string
    Status        string
    ContentLength int64
    Headers       map[string][]string
}

type NCOutput struct {
    Host   string
    Result string
}

{{- with .CURLOutput -}}
<section id="curlOutput">
    <p><strong>Executed curl to {{.URL}}</strong></p>
    <p>{{.Protocol}}</p>
    <p>{{.Status}}</p>
    <p>{{.ContentLength}}</p>
    {{ range $key, $val := .Headers -}}
    <p><strong>{{$key}}:</strong> {{$val}}</p>
    {{- end }}
    <br/>
</section>
{{ end }}
{{ with .NCOutput -}}
  <section id="ncOutput">
    <p><strong>Executed netcat to {{.Host}}</strong></p>
    <p>{{.Result}}</p>
</section>
{{ end }}

https://play.golang.org/p/dOfLc_5bl8b

Upvotes: 2

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