Merge pull request RossWilliams#49 from RossWilliams/feat/nullable-ob…

…jects feat: handle nullable objects
Aaronius · Jun 29, 2021 · f0c2d0f · f0c2d0f
2 parents cfaac6f + 7ff58dd
commit f0c2d0f
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Showing 2 changed files with 67 additions and 41 deletions.
diff --git a/src/caseConvert.ts b/src/caseConvert.ts
@@ -103,39 +103,45 @@ export type ToCamel<S extends string | number | symbol> = S extends string
     : Uncapitalize<S>
   : never;
 
-export type ObjectToCamel<T extends object | undefined> = T extends undefined
-  ? undefined
-  : {
-      [K in keyof T as ToCamel<K>]: T[K] extends Array<unknown>
-        ? T[K] extends Array<infer ArrayType>
-          ? ArrayType extends object
-            ? Array<ObjectToCamel<ArrayType>>
-            : T[K]
-          : never
-        : T[K] extends object | undefined
-        ? ObjectToCamel<T[K]>
-        : T[K];
-    };
+export type ObjectToCamel<T extends object | undefined | null> =
+  T extends undefined
+    ? undefined
+    : T extends null
+    ? null
+    : {
+        [K in keyof T as ToCamel<K>]: T[K] extends Array<unknown>
+          ? T[K] extends Array<infer ArrayType>
+            ? ArrayType extends object
+              ? Array<ObjectToCamel<ArrayType>>
+              : T[K]
+            : never
+          : T[K] extends object | undefined | null
+          ? ObjectToCamel<T[K]>
+          : T[K];
+      };
 
 export type ToPascal<S extends string | number | symbol> = S extends string
   ? S extends `${infer Head}_${infer Tail}`
     ? `${Capitalize<Head>}${Capitalize<ToCamel<Tail>>}`
     : Capitalize<S>
   : never;
 
-export type ObjectToPascal<T extends object | undefined> = T extends undefined
-  ? undefined
-  : {
-      [K in keyof T as ToPascal<K>]: T[K] extends Array<unknown>
-        ? T[K] extends Array<infer ArrayType>
-          ? ArrayType extends object
-            ? Array<ObjectToPascal<ArrayType>>
-            : T[K]
-          : never
-        : T[K] extends object | undefined
-        ? ObjectToPascal<T[K]>
-        : T[K];
-    };
+export type ObjectToPascal<T extends object | undefined | null> =
+  T extends undefined
+    ? undefined
+    : T extends null
+    ? null
+    : {
+        [K in keyof T as ToPascal<K>]: T[K] extends Array<unknown>
+          ? T[K] extends Array<infer ArrayType>
+            ? ArrayType extends object
+              ? Array<ObjectToPascal<ArrayType>>
+              : T[K]
+            : never
+          : T[K] extends object | undefined | null
+          ? ObjectToPascal<T[K]>
+          : T[K];
+      };
 
 export type ToSnake<S extends string | number | symbol> = S extends string
   ? S extends `${infer Head}${CapitalChars}${infer Tail}` // string has a capital char somewhere
@@ -179,21 +185,24 @@ export type ToSnake<S extends string | number | symbol> = S extends string
     : S /* 'abc'  */
   : never;
 
-export type ObjectToSnake<T extends object | undefined> = T extends undefined
-  ? undefined
-  : {
-      [K in keyof T as ToSnake<K>]: T[K] extends Array<unknown>
-        ? T[K] extends Array<infer ArrayType>
-          ? ArrayType extends object
-            ? Array<ObjectToSnake<ArrayType>>
-            : T[K]
-          : never
-        : T[K] extends object | undefined
-        ? ObjectToSnake<T[K]>
-        : //  Exclude<T[K], undefined> extends object
-          //  ? ObjectToSnake<Exclude<T[K], undefined>>
-          T[K];
-    };
+export type ObjectToSnake<T extends object | undefined | null> =
+  T extends undefined
+    ? undefined
+    : T extends null
+    ? null
+    : {
+        [K in keyof T as ToSnake<K>]: T[K] extends Array<unknown>
+          ? T[K] extends Array<infer ArrayType>
+            ? ArrayType extends object
+              ? Array<ObjectToSnake<ArrayType>>
+              : T[K]
+            : never
+          : T[K] extends object | undefined | null
+          ? ObjectToSnake<T[K]>
+          : //  Exclude<T[K], undefined> extends object
+            //  ? ObjectToSnake<Exclude<T[K], undefined>>
+            T[K];
+      };
 
 type CapitalLetters =
   | 'A'

diff --git a/test/caseConvert.test.ts b/test/caseConvert.test.ts
@@ -347,3 +347,20 @@ type T27 = ToCamel<'helloWorld'>;
 const _t27: AssertEqual<T27, 'helloWorld'> = true;
 type T28 = ToCamel<'8HelloWorld'>;
 const _t28: AssertEqual<T28, '8HelloWorld'> = true;
+
+interface I243 {
+  nullable_object: { a_prop: string } | null;
+}
+
+const _c243: I243 = {
+  nullable_object: {
+    a_prop: 'a',
+  },
+};
+interface I2432 {
+  nullableObject: { aProp: string } | null;
+}
+
+const _c2432: I2432 = objectToCamel(_c243);
+
+const _s243: AssertEqual<I243, ObjectToSnake<I2432>> = true;