Hey everyone, building on my last guide about structuring collections (find it here), let’s talk relationships. In the client apps I’ve built, getting these right early saves tons of fixes later, slow lists, broken filters, inconsistent data all stem from rushed relationships.
Relationships connect collections cleanly, avoiding duplicates. Here’s the practical breakdown.
Choosing the right type
I map it to “real world” logic:
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One-to-Many: Most common. One User owns many Listings; many Listings point to one User. I use this even for “one-to-one” needs by limiting to a single link.
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Many-to-Many: For flexible links, like Users favoriting multiple Products. Set up an intermediary collection (e.g., Favorites) with two One-to-Many relationships.
Only add a relationship if you’ll frequently pull data across collections.
Setup steps
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In the database, add a Relationship property.
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Select the target collection and type. Adalo creates the reverse link automatically.
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For Many-to-Many, build the intermediary first.
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Test immediately with magic text on a screen.
Common issues I’ve fixed for clients
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Wrong direction → filters fail. Check the arrow.
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Deep chains → slowdowns. Denormalize key fields when needed.
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Deletes leaving orphans → add specific actions to clean up.
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Big datasets → use counted properties for quick stats.
Marketplace example (continued)
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Listings: One-to-Many from Users (seller)
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Orders: One-to-Many from Users (buyer); links to one Listing
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Reviews: One-to-Many from Listings and Users
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Favorites/Messages: Many-to-Many via intermediaries
This powers smooth dashboards, histories, and real time updates.
Quick checklist
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Type matches real data flow?
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Magic text access is simple?
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Updates/deletes stay consistent?
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Optimized for scale?
Solid relationships make apps feel pro. If yours are tricky or you’re planning a bigger build, share details here or DM me, I’ve sorted these for many projects.
(Part 2 of my practical database series, more coming)
Ali Bazzi
Adalo Community Leader & Expert