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Adding shared properties
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One common pattern in applications is to add shared properties to the schema that are used by multiple objects. For example, you might want to add a created_at and updated_at property to every object in your schema. You can do this by adding an abstract type and using it as a mixin for your other object types.

dbschema/default.gel

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module default {
  abstract type Timestamped {
    required created_at: datetime {
      default := datetime_of_statement();
    };
    required updated_at: datetime {
      default := datetime_of_statement();
    };
  }

  type Deck {
  type Deck extending Timestamped {
    required name: str;
    description: str;

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    };
  };

  type Card {
  type Card extending Timestamped {
    required order: int64;
    required front: str;
    required back: str;

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Since you don't have historical data for when these objects were actually created or modified, the migration will fall back to the default values set in the Timestamped type.

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npx gel migration create

did you create object type 'default::Timestamped'? [y,n,l,c,b,s,q,?]
> y
did you alter object type 'default::Card'? [y,n,l,c,b,s,q,?]
> y
did you alter object type 'default::Deck'? [y,n,l,c,b,s,q,?]
> y
Created /home/strinh/projects/flashcards/dbschema/migrations/00004-m1d2m5n.edgeql, id: m1d2m5n5ajkalyijrxdliioyginonqbtfzihvwdfdmfwodunszstya

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npx gel migrate

Applying m1d2m5n5ajkalyijrxdliioyginonqbtfzihvwdfdmfwodunszstya (00004-m1d2m5n.edgeql)
... parsed
... applied
Generating query builder...
Detected tsconfig.json, generating TypeScript files.
  To override this, use the --target flag.
  Run `npx @gel/generate --help` for full options.
Introspecting database schema...
Generating runtime spec...
Generating cast maps...
Generating scalars...
Generating object types...
Generating function types...
Generating operators...
Generating set impl...
Generating globals...
Generating index...
Writing files to ./dbschema/edgeql-js
Generation complete! 🤘

Update the getDecks query to sort the decks by updated_at in descending order.

app/queries.ts

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      back: true,
      order_by: card.order,
    })),
    order_by: {
      expression: deck.updated_at,
      direction: e.DESC,
    },
  })).run(client);

  return decks;
}

Now when you look at the data in the UI, you will see the new properties on each of your object types.

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Adding shared properties​.mdCopy page

Adding shared properties
.md
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