postgres array elements are always nullable

[leoschweizer]

When you have an array type column like the following:

CREATE TABLE foo (
    things integer[] NOT NULL
);

Postgres still allows elements of this array to be NULL (non-nullability could only be enforced through an additional check constraint).

Yet the derived types e.g. for Insertable do not reflect nullability:

things: number[] | db.Parameter<number[]> | db.DefaultType | db.SQLFragment | db.SQLFragment<any, number[] | db.Parameter<number[]> | db.DefaultType | db.SQLFragment>;

This makes types incompatible to "properly" typed domain logic types, which would look something like this:

interface Foo {
    things: Array<number | null>
}

[olepbr]

The simplest fix here is pretty trivial:

diff --git a/src/generate/pgTypes.ts b/src/generate/pgTypes.ts
index d119bb4..2edde30 100644
--- a/src/generate/pgTypes.ts
+++ b/src/generate/pgTypes.ts
@@ -99,8 +99,8 @@ export const tsTypeForPgType = (pgType: string, enums: EnumData, context: TypeCo
   // see https://www.postgresql.org/docs/current/sql-createtype.html#id-1.9.3.94.5.9
   if (pgType.charAt(0) === '_') {
     const arrayTsType = baseTsTypeForBasePgType(pgType.slice(1), enums, context, config);
-    if (arrayTsType !== null) return arrayTsType + '[]';
+    if (arrayTsType !== null) return `Array<${arrayTsType} | null>`;
   }

…but a proper fix would have to take check constraints into account, too. AFAIK, Zapatos currently makes no attempt to refine types using check constraints.