Linking lists: Link, Rollup, Count, Lookup
Connect customers to their invoices, projects to their tasks — and let Flexlists add up, count and look up what is on the other side.
1. Link to another list
A Link to another list field connects a row to rows of another list (or of the same list). The cell shows the linked rows by their name — the field of the other list you choose to show — as chips.
Create it: in a list choose Add field → Link to another list, pick the list to link to and the field to show. Switch on Allow linking to multiple rows when a row may link to more than one (a customer has many invoices); switch it off when it links to one (an invoice has one customer). You need full access to both lists.
It always works both ways. The other list gets a Link back, named after this list: link invoice 7 to Acme and Acme shows invoice 7. You can rename that field, hide it or change what it shows.
Link rows: open a row and click the field. Search as you type and pick rows, create a new row in the other list with ＋ Create, or Paste names (one per line) to link many at once. Names that match nothing are listed, never silently dropped.
2. Rollup, Count and Lookup through a link
These fields read the rows a Link points to. They are calculated by Flexlists and kept up to date when links or linked rows change, so they are read only. While a large list is being recalculated a cell shows calculating….
| Field | What it shows | Example |
|---|---|---|
| Rollup | One value calculated over a field of the linked rows: SUM, AVG, MIN, MAX, COUNT, COUNTA, COUNTALL, COUNTUNIQUE, EARLIEST, LATEST, AND, OR, XOR, ARRAYJOIN, CONCAT, ARRAYUNIQUE, ARRAYCOMPACT (the Airtable names). | Customers → "Paid total" = SUM of Amount of the linked Invoices, only where Paid is Yes |
| Count | How many rows are linked (optionally only those that match a condition). | Projects → "Open tasks" = Count of the linked Tasks where Status is not Done |
| Lookup through a link | The values of one field of the linked rows, as a list (optionally distinct, sorted, limited). | Invoices → "Customer e-mail" = the E-mail of the linked Customer |
Create one: Add field → Rollup, Count or Lookup through a link. Pick the Link field of this list, then the field of the linked list and the function (only the functions that fit that field are offered), and optionally Only where conditions. A live preview shows the result on three of your rows before you save. Not sure how? Describe what you want and click ✦ Write it for me, or ✦ Explain an existing one.
A list must first have a Link to another list. A Formula can use a Rollup (and a Rollup can read a Formula); setups that would go round in a circle are refused when you save, naming the chain.
3. The rows behind a value
Click a Rollup, Count or Lookup value in the grid or in a row to see the linked rows it was calculated from, with what each row contributes (and "Only rows where …" when the field has conditions). From there, Open the other list if you have a view of it.
4. In views, forms, import and the API
- Views: filter a Link on has any of / has all of / has none of rows, and Rollup / Count / Lookup values like numbers, dates, Yes / No or text. Sort and group by them, and see column totals of number results (also per group). Kanban and Gallery cards show the visible Links as chips and the computed values; the calendar's list mode shows them in a line under each item.
- Forms: a Link field in a form shows the same picker, so people choose rows of the other list instead of typing.
- Import from Airtable or Baserow: linked record fields become Links to another list, and rollup, count and lookup fields become Rollup, Count and Lookup through a link — the functions have the same names.
- Exports: Links and lists are written as text (Acme, Beta); JSON keeps them as arrays.
- API: a Link reads as
[{ "id", "label" }]and is written as an array of row ids; Rollup, Count and Lookup are read only. See the REST API reference.
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