Low Search - How to specify a default filter for {exp:low_search:results}?

Question

Based on the documentation, {exp:low_search:results} has a default:parameter param.

Lets say that I have a channel foo that has relationship field y where the entries have entry_id 1,2 or 3

Can I make {exp:low_search:results} default the search to filter for y?

Does at least one of the code below work?

{exp:low_search:results
   default:y="1" 
}

or

{exp:low_search:results
   default:y[]="1" 
}

or

{exp:low_search:results
   default:child:y="" 
}

or

{exp:low_search:results
   default:child:y[]="" 
}

Answer 1

Your third example should work. It's the regular parameter name, prefixed with default:. The parameter name for the (child) Relationship filter is child:field_name, so the default version becomes default:child:field_name. Applied to the Results tag, this becomes:

{exp:low_search:results default:child:field_name="1|2|3"}

Note: The square brackets [] only apply to input fields in your Form and only for multi-valued attributes. It never appears in either parameter names of an EE tag or variable names.

Square brackets are only used in the name attribute of <input>, <select> or <textarea> HTML elements.