Related To query

You need to use the has notation in Twig for associative arrays using {}, rather than the normal array notation using [].

This should work:

{% set relatedTo = [ 'and', { field: 'team', targetElement: teamCategories }, { field: 'location', targetElement: locationEntries }, ] %} 

Edit: If you want to conditionally check whether any of the relatedTo parameters exist and build the query accordingly, you could do something like this:

{% set relatedTo = null %} {% set locationRelationCriteria = locationEntries ? { field: 'location', targetElement: locationEntries } : {} %} {% set teamRelationCriteria = teamCategories ? { field: 'team', targetElement: teamCategories } : {} %} {% set specialismRelationCriteria = specialismCategories ? { field: 'specialism', targetElement: specialismCategories } : {} %} {% set relationCriteraCount = locationRelationCriteria | length + teamRelationCriteria | length + specialismRelationCriteria | length %} {# relationCriteriaCount will equal 2 * the number of relation criteria with values, since the length of the criteria hash with values is 2 #} {# so if relationCriteriaCount > 2, there must be more than one criteria with values, so we'll need to 'and' them together #} {% if relationCriteraCount > 2 %} {% set relatedTo = [ 'and' ] %} {# Now go through each criteria and merge if it is not empty #} {% if locationRelationCriteria %} {% set relatedTo = relatedTo | merge([locationRelationCriteria]) %} {% endif %} {% if teamRelationCriteria %} {% set relatedTo = relatedTo | merge([teamRelationCriteria]) %} {% endif %} {% if specialismRelationCriteria %} {% set relatedTo = relatedTo | merge([specialismRelationCriteria]) %} {% endif %} {% elseif relationCriteraCount == 2 %} {# relationCriteraCount == 2 so there must be only one relation criteria with values #} {% set relatedTo = locationRelationCriteria ?: teamRelationCriteria ?: specialismRelationCriteria ?: null %} {% endif %} {% if relatedTo %} {% set entries = craft.entries({ section: 'people' }).relatedTo(relatedTo) %} {% endif %} 

Thanks for the pointers and help with this @Steve - so after some struggles have finally got this working.

So needed to pass related ids or elements likes so (using ids for brevity):

{% set entries = craft.entries({ section: 'people' }).relatedTo({ targetElement: [ 'and', 7, 136 ] }) %} 

The issue before was (based on the documentation) abstracting the target elements I wanted to query into separate array elements, eg:

[ 'and', { targetElement: 7 }, { targetElement: 136 } ] 

Hopefully, that helps somebody else experiencing similar issues. The same principle works at a plugin/PHP level, eg:

$peopleEntries = Entry::find()->section('people')->relatedTo( ['targetElement'=>['and',7, 136]] );