I have created with success a view to show some past events using views: hidden link
I can filter by "categories" but I want to add another filter by year (if possible a drop-down with options for 2018, 2017, 2016...). The filter should be based on the custom field ("start day" of the event).
I think I didn't use the correct expression in the title of my post.
The solution you give me is a good alternative, but what I really want is filter results by year using a select menu instead grouping the results by year (because it will have lots of events by year).
The filter should be based on the custom date field, not on the post date.
So, to do so, to display a dropdown for years, either you need to create a taxonomy which will have years as terms and assign this taxonomy to your post type so you will be able to display years as select dropdown.
Once you do that, please share problem URL and access details, as this needs to use view's filter or other hooks to achieve what you are looking for. Please do not forget to mention which custom date field you want to compare against year filter.
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