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Conditional Logic with Handlebars

This article demonstrates how to use conditional logic in Iterable templates. Find more information in the Personalizing Templates with Handlebars article.

In this article

Display a dynamic-length array in a table with rotating background colors

The example code below uses the following Handlebars helpers to display a dynamic table that displays the names of a user's cats, as pulled from a cats array on their user profile:

<table cellpadding="4" cellspacing="1" width="150px">
    <thead>
        <tr>
            <th scope="col" style="background-color:#000099; color:#FFFFFF">Cat Names</th>
        </tr>
    </thead>
    <tbody>
        {{#ifGt cats.size 1}}
            {{#each cats}}
                {{#ifModEq @index 2 0}}
                    <tr style="background-color:#0099CC; color:#FFFFFF">
                        <td>
                            {{name}}
                        </td>
                    </tr>
                {{else}}
                    <tr style="background-color:#FFFFFF; color:#000000">
                        <td>
                            {{name}}
                        </td>
                    </tr>
                {{/ifModEq}}
            {{/each}}
        {{else}}
            {{#ifEq cats.size 1}}
                <tr style="background-color:#FFFFFF; color:#000000">
                    <td>
                        {{cats.[0].name}}
                    </td>
                </tr>
            {{/ifEq}}
        {{/ifGt}}
    </tbody>
</table>

Examples

The following JSON will generate the preview below:

{
    "cats": [{
        "name": "Biscuit"
    }, {
        "name": "Lucifer"
    }, {
        "name": "Arya"
    }]
}

Another example:

{
    "cats": [{
        "name": "Biscuit"
    }]
}

Check two optional fields for a value

This example assumes that a user profile contains a value for one of two fields: selected_city or city. To check if either of these fields is set to New York, use defaultIfEmpty:

{{#ifMatchesRegexStr (defaultIfEmpty selected_city city) "New York"}}  
    I <3 New York  
{{/ifMatchesRegexStr}}

If selected_city has a value, defaultIfEmpty returns it; otherwise, it returns the value of city. This value is then compared against the string "New York".

Randomly display one of three values

This example outputs one of three values for a subject line, depending on the send time (in seconds). Because send time will vary based on trigger time and processing time, this approach should lead to a nearly even distribution of subject line alternatives.

NOTE

To measure differences in engagement across variations, use an experiment instead of the method described here. This method does not record the variation used at send time.

{{#ifEq (math (timestamp) '%' 3) 0}}  
    Welcome to Iterable!  
{{else}}
    {{#ifEq (math (timestamp) '%' 3) 1}}  
        Greetings from Iterable!  
    {{else}}  
        Welcome, {{firstName}}!  
    {{/ifEq}}
{{/ifEq}}

Display a fallback value if a user profile field is empty

No matter how good your data is, sometimes you'll be missing information about some of your users — which can make it tricky to send personalized messages. To avoid sending messages with blank fields, you can add fallback values that will display when a user profile field is empty:

Hi {{#ifEq firstName "firstName"}}
    {{else}}
       {{defaultIfEmpty firstName "there"}}!
    {{/ifEq}}

Want to learn more?

For more information about some of the topics in this article, check out this Iterable Academy course. Iterable Academy is open to everyone — you don't need to be an Iterable customer!

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