--- title: How Relationships Work in Data Connect | daily.dev description: Firebase Data Connect supports relational data modeling using GraphQL schema syntax, including one-to-one, one-to-many, and many-to-many relationships. The... canonical: https://daily.dev/posts/how-relationships-work-in-data-connect-eclgcraff twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How Relationships Work in Data Connect | daily.dev og:description: Firebase Data Connect supports relational data modeling using GraphQL schema syntax, including one-to-one, one-to-many, and many-to-many relationships. The... og:url: https://daily.dev/posts/how-relationships-work-in-data-connect-eclgcraff og:image: https://api.daily.dev/og/posts/ECLGCraFf.png og:image:alt: How Relationships Work in Data Connect og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How Relationships Work in Data Connect **[Firebase](https://daily.dev/sources/firebase-blog)** · 7 min read · 0 upvotes · 0 comments ## Summary Firebase Data Connect supports relational data modeling using GraphQL schema syntax, including one-to-one, one-to-many, and many-to-many relationships. The walkthrough shows how to define primary and foreign keys using directives like @unique and @ref, how composite keys work with the key argument, and how Data Connect auto-generates implicit fields in implicit.gql for tables like Movie, MovieMetadata, User, FavoriteMovie, Actor, and MovieActor join tables. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I define a one-to-one relationship between two tables in Firebase Data Connect? Use the @unique directive on a reference field in the dependent table. For example, adding movie: Movie! @unique to a MovieMetadata type creates a movieId foreign key field that must be unique, enforcing that each Movie has exactly one associated MovieMetadata record and vice versa. _Developers modeling relational schemas can track Data Connect guidance like this on daily.dev._ ### How do I create a many-to-many relationship with a join table in Firebase Data Connect? Create a join table type with a composite key referencing both related types, such as MovieActor @table(key: ["movie", "actor"]) containing movie: Movie! and actor: Actor! fields. Data Connect implicitly generates movieId and actorId foreign key fields in implicit.gql, and additional columns like role can store per-pair data. _Teams designing many-to-many schemas can keep patterns like this handy via daily.dev._ ### What does the @ref directive do in Firebase Data Connect schemas? The @ref directive creates a field in the current table that references the primary key of another type, similar to @unique but without the uniqueness constraint. Writing @ref is often optional since it is implied when a field type points to another table, such as movie: Movie! in a FavoriteMovie table implying @ref(fields: "movieId", references: "id"). _daily.dev helps developers comparing GraphQL-based database tools like Data Connect stay current on schema syntax._ ## Similar posts on daily.dev - [How Firestore Structures Data and How to Perform CRUD Operations With It](https://daily.dev/posts/how-firestore-structures-data-and-how-to-perform-crud-operations-with-it-odioykply) · freeCodeCamp · 1 upvotes · 0 comments - [Building type-safe applications with Drizzle ORM in Aurora DSQL](https://daily.dev/posts/building-type-safe-applications-with-drizzle-orm-in-aurora-dsql-ysp70xb5v) · AWS Database Blog · 3 upvotes · 0 comments --- Tags: [#database](https://daily.dev/tags/database), [#graphql](https://daily.dev/tags/graphql), [#firebase](https://daily.dev/tags/firebase) [View this post on daily.dev](https://daily.dev/posts/how-relationships-work-in-data-connect-eclgcraff) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How Relationships Work in Data Connect","url":"https://daily.dev/posts/how-relationships-work-in-data-connect-eclgcraff","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-relationships-work-in-data-connect-eclgcraff"},"datePublished":"2026-08-23T12:19:03.866Z","dateModified":"2026-08-23T12:24:03.672Z","description":"Firebase Data Connect supports relational data modeling using GraphQL schema syntax, including one-to-one, one-to-many, and many-to-many relationships. 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