fix(types): overrideTypes merging with maybeSingle

Author: avallete

src/PostgrestBuilder.ts

@@ -10,6 +10,7 @@ import type {
   IsValidResultOverride,
 } from './types'
 import PostgrestError from './PostgrestError'
+import { ContainsNull } from './select-query-parser/types'
 
 export default abstract class PostgrestBuilder<Result, ThrowOnError extends boolean = false>
   implements
@@ -257,14 +258,20 @@ export default abstract class PostgrestBuilder<Result, ThrowOnError extends bool
     NewResult,
     Options extends { merge?: boolean } = { merge: true }
   >(): PostgrestBuilder<
-    IsValidResultOverride<Result, NewResult, true, false, false> extends true
-      ? MergePartialResult<NewResult, Result, Options>
+    IsValidResultOverride<Result, NewResult, false, false> extends true
+      ? // Preserve the optionality of the result if the overriden type is an object (case of chaining with `maybeSingle`)
+        ContainsNull<Result> extends true
+        ? MergePartialResult<NewResult, NonNullable<Result>, Options> | null
+        : MergePartialResult<NewResult, Result, Options>
       : CheckMatchingArrayTypes<Result, NewResult>,
     ThrowOnError
   > {
     return this as unknown as PostgrestBuilder<
-      IsValidResultOverride<Result, NewResult, true, false, false> extends true
-        ? MergePartialResult<NewResult, Result, Options>
+      IsValidResultOverride<Result, NewResult, false, false> extends true
+        ? // Preserve the optionality of the result if the overriden type is an object (case of chaining with `maybeSingle`)
+          ContainsNull<Result> extends true
+          ? MergePartialResult<NewResult, NonNullable<Result>, Options> | null
+          : MergePartialResult<NewResult, Result, Options>
         : CheckMatchingArrayTypes<Result, NewResult>,
       ThrowOnError
     >

src/types.ts

@@ -92,20 +92,16 @@ type NonRecursiveType = BuiltIns | Function | (new (...arguments_: any[]) => unk
 type BuiltIns = Primitive | void | Date | RegExp
 type Primitive = null | undefined | string | number | boolean | symbol | bigint
 
-export type IsValidResultOverride<Result, NewResult, Ok, ErrorResult, ErrorNewResult> =
+export type IsValidResultOverride<Result, NewResult, ErrorResult, ErrorNewResult> =
   Result extends any[]
     ? NewResult extends any[]
       ? // Both are arrays - valid
-        Ok
+        true
       : ErrorResult
     : NewResult extends any[]
     ? ErrorNewResult
     : // Neither are arrays - valid
-    // Preserve the optionality of the result if the overriden type is an object (case of chaining with `maybeSingle`)
-    ContainsNull<Result> extends true
-    ? Ok | null
-    : Ok
-
+      true
 /**
  * Utility type to check if array types match between Result and NewResult.
  * Returns either the valid NewResult type or an error message type.
@@ -117,14 +113,21 @@ export type CheckMatchingArrayTypes<Result, NewResult> =
     : IsValidResultOverride<
         Result,
         NewResult,
-        NewResult,
         {
           Error: 'Type mismatch: Cannot cast array result to a single object. Use .returns<Array<YourType>> for array results or .single() to convert the result to a single object'
         },
         {
           Error: 'Type mismatch: Cannot cast single object to array type. Remove Array wrapper from return type or make sure you are not using .single() up in the calling chain'
         }
-      >
+      > extends infer ValidationResult
+    ? ValidationResult extends true
+      ? // Preserve the optionality of the result if the overriden type is an object (case of chaining with `maybeSingle`)
+        ContainsNull<Result> extends true
+        ? NewResult | null
+        : NewResult
+      : // contains the error
+        ValidationResult
+    : never
 
 type Simplify<T> = T extends object ? { [K in keyof T]: T[K] } : T
 

test/override-types.test-d.ts

@@ -60,7 +60,7 @@ const postgrest = new PostgrestClient<Database>(REST_URL)
   let result: typeof singleResult.data
   expectType<TypeEqual<(typeof result)['custom_field'], string>>(true)
 }
-// Test with maybeSingle()
+// Test with maybeSingle() merging with new field
 {
   const maybeSingleResult = await postgrest
     .from('users')
@@ -71,7 +71,50 @@ const postgrest = new PostgrestClient<Database>(REST_URL)
     throw new Error(maybeSingleResult.error.message)
   }
   let maybeSingleResultType: typeof maybeSingleResult.data
-  let expectedType: { custom_field: string } | null
+  let expectedType: {
+    age_range: unknown
+    catchphrase: unknown
+    data: CustomUserDataType | null
+    status: 'ONLINE' | 'OFFLINE' | null
+    username: string
+    custom_field: string
+  } | null
+  expectType<TypeEqual<typeof maybeSingleResultType, typeof expectedType>>(true)
+}
+// Test with maybeSingle() merging with override field
+{
+  const maybeSingleResult = await postgrest
+    .from('users')
+    .select()
+    .maybeSingle()
+    .overrideTypes<{ catchphrase: string }>()
+  if (maybeSingleResult.error) {
+    throw new Error(maybeSingleResult.error.message)
+  }
+  let maybeSingleResultType: typeof maybeSingleResult.data
+  let expectedType: {
+    age_range: unknown
+    catchphrase: string
+    data: CustomUserDataType | null
+    status: 'ONLINE' | 'OFFLINE' | null
+    username: string
+  } | null
+  expectType<TypeEqual<typeof maybeSingleResultType, typeof expectedType>>(true)
+}
+// Test with maybeSingle() replace with override field
+{
+  const maybeSingleResult = await postgrest
+    .from('users')
+    .select()
+    .maybeSingle()
+    .overrideTypes<{ catchphrase: string }, { merge: false }>()
+  if (maybeSingleResult.error) {
+    throw new Error(maybeSingleResult.error.message)
+  }
+  let maybeSingleResultType: typeof maybeSingleResult.data
+  let expectedType: {
+    catchphrase: string
+  } | null
   expectType<TypeEqual<typeof maybeSingleResultType, typeof expectedType>>(true)
 }
 // Test replacing behavior