Twig json_decode gives Syntax Error

Question

I'm trying to use the json_decode twig filter from Craft to decode an array of entry objects that got encoded in a macro.

In the macro, the array of entry objects gets encoded by json_encode and echoed:

{{ orderedFutureEvents|json_encode }}

This is how the macro value gets set in the template:

{% set events = craft.entries()
        .section('eventPost')
        .all() %}
{% import "_macros/events.html" as eventsMacro %}
{% set futureEvents %}
    {{ eventsMacro.futureEvents(events)|json_decode }}
{% endset %}

When loading the page it's used on, I get a syntax error:

Invalid Argument – yii\base\InvalidArgumentException

Syntax error.

The specific lines that trows the error:

yiisoft/yii2/helpers/BaseJson.php at line 133

yiisoft/yii2/helpers/BaseJson.php at line 107

Compiled template line:

$context["test"] = craft\helpers\Json::decode((isset($context["futureEvents"]) || array_key_exists("futureEvents", $context) ? $context["futureEvents"] : (function () { throw new RuntimeError('Variable "futureEvents" does not exist.', 19, $this->source); })()));

What's causing this error?

Full macro:

{% macro futureEvents(events) %}
    {% set today = "now"|date('d/m/Y') %}
    {% set now = "now"|date('U') %}
    {% set futureEvents = [] %}
    {% for event in events %}
        {% for block in event.calendar.level(1).all() %}
            {% switch block.type.handle %}
                {% case 'periodOfDays' %}
                    {% if block.endDate|date('d/m/Y') > today  %}
                        {% if block.startDate|date('d/m/Y') < today %}
                            {# Ongoing event #}
                            {% set futureEvents = futureEvents|merge([{'date': today, 'event': event}]) %}
                        {% else %}
                            {# Future event #}
                            {% set futureEvents = futureEvents|merge([{'date': block.startDate|date('d/m/Y'), 'event': event}]) %}
                        {% endif %}
                    {% endif %}
                {% case 'specificDates' %}
                    {% set tempEvent = [] %}
                    {% set break = false %}
                    {% set empty = false %}
                    {% for child in block.children.all() if not break %}
                        {% if child.dateAndTime|date('U') > now %}
                            {# Future event #}
                            {% set tempEvent = [{'date': child.dateAndTime|date('d/m/Y'), 'event': event}] %}
                            {% set break = true %}
                            {# Break because event is found #}
                        {% elseif (child.dateAndTime|date('U') + child.duration*60) > now %}
                            {# Ongoing event #}
                            {% set tempEvent = [{'date': today, 'event': event}] %}
                            {% set break = true %}
                            {# Break because event is found #}
                        {% endif %}
                        {% else %}
                            {% set empty = true %}
                    {% endfor %}
                    {% if tempEvent is same as([]) and empty %}
                        {# Fallback on default #}
                    {% elseif tempEvent is not same as([]) %}
                        {% set futureEvents = futureEvents|merge(tempEvent) %}
                    {% endif %}
            {% endswitch %}
        {% else %}
            {% if event.dateAndTime|date('U') > now %}
                {# Future event #}
                {% set futureEvents = futureEvents|merge([{'date': event.dateAndTime|date('d/m/Y'), 'event': event}]) %}
            {% elseif (event.dateAndTime|date('U') + event.duration*60) > now %}
                {# Ongoing event #}
                {% set futureEvents = futureEvents|merge([{'date': today, 'event': event}]) %}
            {% endif %}
        {% endfor %}
    {% endfor %}
    {% set orderedFutureEvents = [] %}
    {% for key in futureEvents|sort((a, b) => a <=> b)|column('date', 'event')|keys %}
        {% set orderedFutureEvents = orderedFutureEvents|merge([futureEvents[key].event]) %}
    {% endfor %}
    {{ orderedFutureEvents|json_encode|raw }}
{% endmacro %}

Answer 1

Guessing if you change your macro to this, it'll work:

{{ orderedFutureEvents|json_encode|raw }}

The reason being that Twig will return a Markup class that wraps the JSON content when returning from the macro that json_encode doesn't know what to do with.

Passing the contents through |raw returns the original JSON.