Passing Data Between Templates

In Go's templating system, it can be necessary to pass data between multiple templates, particularly when including one template within another. The question arises, "How can I pass data as arguments to an included template and access it within that template?"

To achieve this, you can utilize a custom function that merges the arguments into a single slice value. By registering this function, it can be used within the template invocation. The following code demonstrates how this is done:

package main

import (
    "fmt"
    "html/template"
)

func main() {
    t, err := template.New("t").Funcs(template.FuncMap{
        "args": func(vs ...interface{}) []interface{} { return vs },
    }).Parse("{{ template \"image_row\" args . 5 }}")
    if err != nil {
        fmt.Println(err)
        return
    }

    err = t.Execute(template.Must(template.ParseFiles("index.html", "image_row.html")), nil)
    if err != nil {
        fmt.Println(err)
        return
    }
}

// index.html
{{ template "image_row" . | 5 }}

// image_row.html
{{ define "image_row" }}
   To stuff here {{index . 0}} {{index . 1}}
{{ end }}

Within the image_row template, the arguments can be accessed using the built-in index function. For example, {{index . 0}} would access the first argument (index 0) passed from the index.html template, in this case the number 5.

This solution provides a versatile way to pass and access data between multiple templates, enabling custom functionality and efficient code reuse.