Unique Constraint on string

jdgamble555 · March 14, 2023, 3:50am

This does seem to be on the roadmap for sooner than later. They said they do want to build it from dql layer up.

Feature Request - Multiple and Single Primary and Unique Keys

opened 12:49AM - 26 Aug 22 UTC

kind/feature area/graphql community

Related to [this issue](https://github.com/dgraph-io/dgraph/issues/8176) for ref…erence. # Keys **Composite Key** - has more than one attribute **Compound Key** - a specific composite key where both attributes are also foreign keys ## [PK (Primary Key)](https://www.w3schools.com/sql/sql_primarykey.asp) - _Right now, we can do this:_ ### Single PK or @id (external id) ```graphql type User { username: String! @id name: String! } ``` ### SQL ```sql ADD PRIMARY KEY(username) ``` ___ ### Composite PK or @id ```graphql type User { username: String! @id email: String! @id } ``` ### SQL ```sql ADD PRIMARY KEY(username, email) ``` ___ ## [Unique Keys (Unique)](https://www.w3schools.com/sql/sql_unique.asp) - **What we need to be able to do:** ### Single Unique or @unique ```graphql type User { id: ID! @id username: String! @unique name: String! } ``` ### SQL ```sql ADD CONSTRAINT UNIQUE (username) ``` ___ ### Multiple Uniques or @unique ```graphql type User { id: ID! @id username: String! @unique email: String! @unique } ``` ### SQL ```sql ADD CONSTRAINT UNIQUE (username) ADD CONSTRAINT UNIQUE (email) ``` ___ ### Composite Uniques or @unique ```graphql type User @unique(fields: ["firstName", "lastName"]) { email: String! firstName: String! lastName: String! ... } ``` ### SQL ```sql ADD CONSTRAINT UNIQUE (firstName, lastName) ``` ## Compound Keys - composite keys on foreign keys or nested fields ```graphql type Book { id: ID! name: String! ... } type User { id: ID! name: String! reviews: [Review]! ... } type Review @unique(fields: ["reviewer.id", "book.id"]) { reviewer: User! book: Book! createdAt: DateTime! } ``` ### SQL In SQL, there would be a composite pk on the junction table [book_id_fk, user_id_fk, created_at]: ```sql ADD PRIMARY KEY(book_id_fk, user_id_fk) ``` So theoretically, there should be a unique key on reviewer.id and book.id. This should also be possible for one foreign key, although I can't think of an example. ___ **UPDATE:** 11/2/22 - The @unique (not the @id) should be able to be null. ```graphql type User { id: ID! @id username: String @unique // no ! in input email: String! @unique } ``` Referring to [this post](https://github.com/dgraph-io/dgraph/issues/8117), you should also be able to get multiple fields based on their **COMPOSITE** primary or unique key(s) as well as [individual unique keys](https://dgraph.io/docs/graphql/schema/ids/), which is how it currently works: ```graphql query { getUser(username: 'jdgamble555', email: 'someone@something.com') { username ... } } ``` So we really have a few feature requests here: 1. Possibly rename @id to @unique 2. Allow top level @unique directive for multiple "composite" unique constraints 3. Allow "composite" unique constraints on nested fields (only one level), same as junction table 4. Make sure you can search with "get" for the composite fields 5. Allow nullable unique, as "no value" should not break the constraint #2 is the main request here ___ - The GraphQL schema should fail if someone tries to add this directive on a field where there are "non unique" values. - Some of this should be build on the [DQL level up](https://github.com/dgraph-io/dgraph/issues/8408), which is a different feature request. This should be implemented first. J ___ Just for more reference - https://github.com/outcaste-io/issues/issues/26

J

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Unique Constraint on string

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