If, For and Switch

The if statement is used to execute code based on a condition, the for statement is used to iterate over a slice (but also maps, strings and channels) and the switch statement allows a variable to be tested for equality against a list of values.

If

The if statement executes its body if the condition, that can have any type, is valuated to true. For example the following statement:

{% if stock > 10 %}
  Wide availability
{% end %}

shows "Wide availability" if stock is greater than 10.

Note that in programs, unlike in templates, the if condition can only be a boolean value.

A condition is false for the values false, 0, 0.0, "" and nil, for nil or empty slices and maps. Apart from some special cases, it is true for all other values.

For example:

""               // is false, it is an empty string
"0"              // is true
true             // is true
[]string{}       // is false, it is an empty slice
map[int]string{} // is false, it is an empty map
0.1              // is true 
[]int{1,2}       // is true

If you want to execute one code or another based on a condition, you can write:

{% if stock > 10 %}
  Wide availability
{% else %}
  Limited availability
{% end %}

  Wide availability

Scriggo also supports the else if form:

{% if stock > 10 %}
  Wide availability
{% else if stock > 0 %}
  Limited availability
{% else %}
  Not available
{% end %}

  Wide availability

For

The for statement iterates over a slice (but also a map, a string and a channel). For example:

{% for article in articles %}
  <div>{{ article.Title }}</div>
{% end %}

It assigns an element to a variable in each iteration. In the previous example, the article variable is implicitly declared and has the same type of the elements of articles. It is only visible in the body of the for statement.

With this for statement form, you can use an else block:

{% for article in articles %}
  <div>{{ article.Title }}</div>
{% else %}
   <div>There are no articles</div>
{% end %}

The else block is executed if the for block is not executed.

This for statement form can be used only in templates, but you can also use all the other forms of the for statement that can be used in programs.

for range

The for range form is similar to the for in form, but it also allows you to assign the element index, starting from zero:

{% for i, article := range articles %}
  <div>{{ i+1 }}. {{ article.Title }}</div>
{% end %}

Also in the for range form you can use an else block that is executed if the for block is not executed.

{% for i, article := range articles %}
  <div>{{ i+1 }}. {{ article.Title }}</div>
{% else %}
   <div>There are no articles</div>
{% end %}

for condition

The for statement can be used with a condition. In this case the body is executed as long as the condition is true.

{% for i < len(articles) %}
  <div>{{ i+1 }}. {{ articles[i].Title }}</div>
  {% i++ %}
{% end %}

As with the if statement, the condition of the for statement can have any type.

for loop

The for statement alone, without a condition, executes its body until it is interrupted with a break statement.

{% for %}
  {% var v = value() %}
  {% if not v %}{% break %}{% end %}
{% end %}

for init; condition; post

The for init; condition; post form has three parts separated by a semicolon. The first part declares or assigns to a variable before the first iteration. The second part is the condition and the last part usually increases a variable before the next iteration.

The iteration continues as long as the condition is true.

{% for i := 0; i < len(articles); i++ %}
  <div>{{ i+1 }}. {{ articles[i].Name }}</div>
{% end %}

continue

The continue statement can be used in the body of a for statement to terminate the current iteration and continue with the next one.

For example, the following code shows only products with a price:

{% for product in products %}
  {% if not product.Price %}
    {% continue %}
  {% end if %}
  <div>{{ product.Name }}</div>
{% end %}

break

The break statement can be used to stop the execution of a for statement.

For example, the following code shows only 1 2 3.

{% for n in []int{1, 2, 3, 4, 5} %}
  {% if n > 3 %}
    {% break %}
  {% end if %}
  {{ n }}
{% end %}

Switch

The switch statement can be used as an alternative to the if statement when the condition is not simply true or false. This statement executes a case based on the value of its condition.

{% switch department.Name %}
{% case "Tappeti" %}
  Rugs and rugs on offer for yuor home
{% case "Cuscini", "Federe" %}
  Offers for the bedroom
{% default %}
  Specials
{% end %}

Offers for the bedroom

Case values must have the same type of the condition. The cases are evaluated in order and only the first case that has the same value as the condition is executed. If there are no cases with that value and there is a default case, the default case is executed.

A switch may or may not have a condition. If it doesn't, the case expressions must be boolean.

{% switch %}
{% case stock > 10 %}
  Available
{% case name == "Cuscini" %}
  Offers for the bedroom
{% default %}
  Specials
{% end %}