ruby on rails - Using associations with pluck -

im trying array project name , task title. task title in projects model. should use pluck or select or where?

@completed_tasks = task.where(completed:true).select("projects.project_name", :title) 

first of all, should use join data projects table. , can use either pluck or select.

for example (suppose in task model have belongs_to :project)

@completed_tasks = task.where(completed:true).join(:project).select("projects.project_name", :title)