How to link one Object to another

A Linked record is a field type that lets one record point at another: a quality check that knows which production run it belongs to, a production run that knows which factory made it. You add it to an Object, a kind of record your team defines, on the Object's Fields tab in Settings › Objects. Start at What is an Object? if Objects are new to you.

People pick from a real list instead of typing a name, so the value survives a rename and the list of records can be filtered by it. This page covers which way round the link should point, how to add it, and the list the record on the far end can show.

Before you start

You need to be an admin, because Settings only appears for admins. Both sides of the link have to exist before you can join them, so if you are pointing at an Object you defined yourself, create it first with How to create an Object.

Points at offers the records Tideswell ships with, such as suppliers, products and purchase orders, as well as your own Objects. So an Object you defined can point straight at the factory that made the goods. How to choose between a built-in record and your own Object covers which of the two you should be using.

Which way round should the link go?

Put the field on the Object there are more of, pointing at the one there are fewer of. A quality check belongs to exactly one production run, so the field goes on Quality checks. Ten checks can then point at the same run, and the run can list all ten.

Fairgreen Golf Co. defined two Objects of its own: Production runs, one per style per factory per season, and Quality checks, one per inspection. The Linked record field lives on Quality checks and points at Production runs.

Production runs has its own Linked record field pointing at Suppliers, which is how each run knows its factory. Decide the direction before you save, because the Object a field points at is fixed once the field exists. How to plan your fields before you add them sets out what correcting one costs.

Add the Linked record field

1. Open Settings › Objects, click the Object that will hold the field, and open its Fields tab. For Fairgreen that is Quality checks.
2. Press Add field and type the Label, for example "Production run". Use the words your team already says out loud, because the label is fixed once saved.
3. Open the Type menu and pick Linked record, under the "Choices & links" heading.
4. In Points at, choose the Object this field points at.
5. In the box named after that Object, such as What Production runs calls these, type a name for the list that will appear over there, for example "Quality checks".
6. Press Save field.

The field appears at the bottom of the field list, its type reading "Linked record" with an arrow to the Object it points at. Move it up with the arrows on its row if you want it near the top of the record form. How to add a field and pick its type explains the type menu in full.

What does the reverse view give you?

A list on the far record of everything that points at it, under the name you typed. Open a Fairgreen production run and a "Quality checks" section lists every check whose Production run field names that run, each one a link straight through to it. You add no field on that side to get this.

Name the list in the plural and in your team's own words, because that is what people read on the other record. The list shows on records of your own Objects. When the field points at a supplier, product or other record Tideswell ships with, the name is what lets you switch on the one-per limit below, so fill it in when you want that limit.

When a run has no checks yet, the section says so and explains that one joins the list when someone sets its Production run field to this record. When there are more than the section shows, See all opens the Quality checks list already filtered to that run.

Should you limit it to one per record?

Tick Only one per (followed by the Object's name) when the connection is genuinely one to one and a second link would be a mistake. Fairgreen gives Quality checks a second Linked record field, Final inspection for, capped at one per production run, so nobody can log two final inspections against the same run.

• Leave it clear when many are expected. Quality checks against a production run should be uncapped, because there are meant to be several.
• Tick it when a second link would be a duplicate: one compliance certificate per factory, one final inspection per run.
• Name the reverse view first. The cap describes the same relationship as the list, so a field with the box ticked and no name is refused with "Turn on a reverse label before turning on the cap."

Once the cap is on, a record that picks a target someone else already holds is refused when it is saved. The message names the record that holds it, so the person can open that one and decide which link is right.

What if records already break the one-per rule?

You are told before anything changes. Tick Only one per in the Reverse view dialog and Tideswell checks the records already saved.

If any target is pointed at more than once, the dialog says how many already have more than one and lists each target with the records pointing at it. Save stays greyed out while that list is showing, and the dialog asks you to fix these first.

Open each record, decide which link is the correct one, change or clear the others, then come back and tick the box again. Pressing Cancel changes nothing.

What can you change later?

Two things: the name of the reverse view list, and whether the one-per cap is on. Both sit behind the Reverse view button on the field's row, which opens a dialog titled "Reverse view for" the field's name, and you can edit them whenever you like.

The Object the field points at, along with the field's label and type, is settled when you press Save field. A few things carry on working as your workspace changes:

• Renaming the Object on either end keeps every link, and the reverse view keeps listing the same records. See How to rename, reorder or retire an Object.
• A Linked record field can be filtered on the record list, so you can narrow Quality checks to one production run. How to search, filter and save a view shows how to save that as a view.
• Who can open each Object is a separate setting. Check that the people who make these links can view both sides, using How to set who can see and edit an Object.

How does a link feed a calculation?

A Linked record field lets the record that points carry a value in from the record it points at. A quality check can show its production run's Ex factory date, using the formula source "A value from a linked record".

To count or total across many records, link them with Link something in the record's Related section, covered in How to link a record to work, and see what points at it. Counts and totals read those links. How to build a field that works itself out covers both kinds of calculation.