如何从Prisma中的MySql关系表获取数据

Question

In datamodel.graphql

type Ride {
 rideId: String
 productId: String
 passenger: Passenger
 origin: Origin
 destination: Destination
 dateTime: DateTime
 feedback: String
}


type Passenger {
 id: ID! @unique
 firstName: String
 lastName: String
}

type Destination {
 # The unique ID of the destination.
 id: ID! @unique
 latitude: Float
 longitude: Float
 address: String
}

type Origin {
 id: ID! @unique
 latitude: Float
 longitude: Float
 address: String
}


type Report {

 productId: String
 passenger: Passenger
 description: String
}

I deployed this data model and generates a MySql Db, auto queries, mutations with this.

It creates a "Ride", "Passenger", "Report" and "Origin" table in MySql. But it didn't create any column for passenger, origin, destination in "Ride" table.

It separates creates a relation table for this like _PassengerToRide, _OriginToRide, and _DestinationToRide.

Lack of relation establishment in "Ride" table, I couldn't get the details from Passenger, Origin and Destination tables when I query "rides()". Is this the correct way to define the datamodel.graphql. (edited)

Answer 1

Based on your description, this query should "just work":

query {
  rides {
    feedback
    passenger {
      id
    }
    origin {
      id
    }
    destination {
      id
    }
  }
}

Prisma uses the relation table approach you mentioned to keep track if relations between two nodes, for example table _OriginToRide relates to relation @relation(name: "OriginToRide") from your datamodel.

You don't have to change anything on the SQL level to connect the relations afterwards.

Note: The above applies to Prisma database connectors with activated migrations . If your connector doesn't do migrations, different approaches to represent relations are supported. The respective datamodel to support this can be generated by introspecting your existing database schema.