Lookup fields lose data type

If I have a lookup field for a date, it loses its data type as a “date” and I cannot create a timeline block or place events on a calendar. The only solution seems to be making a new column with the data type of “date” and copy/pasting the lookup field info over… manually, every time there is a change or new entry.

Lookup fields return arrays — even if there’s only a single element to the array. Usually Airtable manages to suss out the field type and recognizes it as a date… but not always.¹ Instead of a lookup field, try defining it as a rollup field, one that follows the same link and references the same field in the linked record, but use the following aggregation function:


That should work — but if it doesn’t, you may need to add a format specifier. First, determine in what format the referenced date is being passed by using the aggregation function


Then, modify the first ag function to provide an explicit format specifier, using the codes given here. For example, you might use


  1. Hmmm… it just occurred to me this may be a function of whether the linked-record field is set to allow links to multiple records; I’ll have to test that hypothesis some time
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That had not occurred to me, but I just made sure that the linked fields were set to only allow one record. No luck.

Yeah, I’m still not sure why Airtable can sometimes identify a looked-up date and sometimes not. AFAIK, though, DATETIME_PARSE(values&'') always works — although, conceivably, it might hiccup on certain browser/OS locale settings. If so, DATETIME_PARSE(values&'',[FormatSpecifier]) should take care of it.