DT
Drizzle Team•2mo ago
sebastienbarre

TypeScript type of a table that *always* has a numerical "id" column?

Hello. I'm new to TypeScript and Drizzle, and I'm struggling to describe the correct TypeScript type representing a Drizzle Table that always has a numerical "id" column (the primary key essentially). What I'm trying to do here is to create a generic class parametrized by a table type T that extends from the above constraint. It would feature a findById method that can safely access the "id" property and return a record of type InferSelectModel<T>. Roughly: 
export class EntityDrizzleSQLiteRepository<T extends TableWithNumericId> {
  ...
  table: T;

  async findById(id: number): Promise<InferSelectModel<T> | undefined> {
    const entities = await this.db.select().from(this.table).where(eq(this.table.id, id));
    if (entities.length) {
      return entities[0];
    }
  }
export class EntityDrizzleSQLiteRepository<T extends TableWithNumericId> {
  ...
  table: T;

  async findById(id: number): Promise<InferSelectModel<T> | undefined> {
    const entities = await this.db.select().from(this.table).where(eq(this.table.id, id));
    if (entities.length) {
      return entities[0];
    }
  }
My efforts have failed so far because I don't quite follow how InferSelectModel works at this point. It seems to iterate over T['_']['columns'], so one would think that TableWithNumericId should be a type where the _ property is the same structure as a Table but also has a hard-coded property "id" of type Column<ColumnBaseConfig<"number", any>>, but I have not been able to achieve this so far. I can tell because TypeScript is telling me "Property 'id' does not exist on type 'TableType'.". Ultimately I do not want to programatically test if the property "id" exists using if {...}, I want this code to work as-is because TypeScript understands that "id" exists, by virtue of InferSelectModel having declared it. Thank you
1 Reply
JustWayne
JustWayne•2mo ago

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