add generic interface support for tableSchema function

src/Schema/index.d.ts

@@ -2,26 +2,47 @@
 
 // NOTE: Only require files needed (critical path on web)
 import invariant from '../utils/common/invariant'
-import type { $Exact, $RE } from '../types'
+import type { $Exact, $RE, GetType, IsOptional, RequireKey } from '../types'
 
 import type Model from '../Model'
 
 export type TableName<T extends Model> = string
 export type ColumnName = string
 
 export type ColumnType = 'string' | 'number' | 'boolean'
-export type ColumnSchema = $RE<{
+
+export type StandardColumn = $RE<{
   name: ColumnName
   type: ColumnType
   isOptional?: boolean
   isIndexed?: boolean
 }>
 
+export type MappedColumn<T extends object, K extends keyof T> = {
+  name: K
+  type: GetType<T[K]>
+  isOptional?: IsOptional<T[K]>
+  isIndexed?: boolean
+}
+
+type MakeMappedColumn<
+  T extends object,
+  U = {
+    [K in keyof T]: IsOptional<T[K]> extends true
+      ? RequireKey<MappedColumn<T, K>, 'isOptional'>
+      : MappedColumn<T, K>
+  },
+> = U[keyof U]
+
+export type ColumnSchema<T extends {} | undefined = undefined> = T extends undefined
+  ? StandardColumn
+  : MakeMappedColumn<T>
+
 export type ColumnMap = { [name: ColumnName]: ColumnSchema }
 
-export type TableSchemaSpec = $Exact<{
+export type TableSchemaSpec<T extends {} = unknown> = $Exact<{
   name: TableName<any>
-  columns: ColumnSchema[]
+  columns: ColumnSchema<T>[]
   unsafeSql?: (string) => string
 }>
 
@@ -59,4 +80,8 @@ export function appSchema({ version, tables: tableList, unsafeSql }: AppSchemaSp
 
 export function validateColumnSchema(column: ColumnSchema): void
 
-export function tableSchema({ name, columns: columnArray, unsafeSql }: TableSchemaSpec): TableSchema
+export function tableSchema<T extends {} = unknown>({
+  name,
+  columns: columnArray,
+  unsafeSql,
+}: TableSchemaSpec<T>): TableSchema

src/types.d.ts

@@ -16,3 +16,16 @@ export type Array<Type> = Type[]
 export type $Call<F, T> = any
 
 export type $ReadOnlyArray<T> = T[]
+
+export type RequireKey<T, K extends keyof T> = Omit<T, K> & Required<Pick<T, K>>
+
+export type IsOptional<T> = Exclude<T, string | number | boolean> extends never ? false : true
+
+// Assumes that arrays and objects will be stored as json strings
+export type GetType<T> = T extends string
+  ? 'string'
+  : T extends number
+  ? 'number'
+  : T extends boolean
+  ? 'boolean'
+  : 'string'