Adjust OptionalField transformers to be passed the original/previous transformer

This allows them to transform the value _before_ passing it to the original/previous transformer.

Author: CarsonF

src/common/list-field.ts

@@ -1,6 +1,10 @@
 import { applyDecorators } from '@nestjs/common';
 import { ArrayNotEmpty } from 'class-validator';
-import { OptionalField, type OptionalFieldOptions } from './optional-field';
+import {
+  OptionalField,
+  type OptionalFieldOptions,
+  withDefaultTransform,
+} from './optional-field';
 
 export type ListFieldOptions = OptionalFieldOptions & {
   /**
@@ -14,11 +18,12 @@ export const ListField = (typeFn: () => any, options: ListFieldOptions) =>
     OptionalField(() => [typeFn()], {
       optional: false,
       ...options,
-      transform: (value) => {
+      transform: withDefaultTransform(options.transform, (prev) => (raw) => {
+        const value = prev(raw);
         let out = value ? [...new Set(value)] : value;
         out = options.empty === 'omit' && out.length === 0 ? undefined : out;
-        return options.transform ? options.transform(out) : out;
-      },
+        return out;
+      }),
     }),
     ...(options.empty === 'deny' ? [ArrayNotEmpty()] : []),
   );

src/common/optional-field.ts

@@ -13,9 +13,19 @@ export type OptionalFieldOptions = FieldOptions & {
    * If true, values can be omitted/undefined but not null.
    */
   optional?: boolean;
-  transform?: (value: any) => unknown;
+  transform?: TransformerLink;
 };
 
+type TransformerLink = (prev: Transformer) => Transformer;
+type Transformer<I = any, O = any> = (value: I) => O;
+export const withDefaultTransform =
+  (
+    input: TransformerLink | undefined,
+    wrapping: TransformerLink,
+  ): TransformerLink =>
+  (base) =>
+    input?.(wrapping(base)) ?? wrapping(base);
+
 /**
  * A field that is optional/omissible/can be undefined.
  * Whether it can be explicitly null is based on `nullable`.
@@ -38,13 +48,16 @@ export function OptionalField(...args: any) {
     ...options,
     nullable: nilIn,
   };
+  const defaultTransformer: Transformer = (value) => {
+    if (value === null && !nullOut) {
+      return undefined;
+    }
+    return value;
+  };
+  const finalTransformer =
+    options.transform?.(defaultTransformer) ?? defaultTransformer;
   return applyDecorators(
     typeFn ? Field(typeFn, schemaOptions) : Field(schemaOptions),
-    Transform(({ value }) => {
-      if (value === null && !nullOut) {
-        return undefined;
-      }
-      return options.transform ? options.transform(value) : value;
-    }),
+    Transform(({ value }) => finalTransformer(value)),
   );
 }

src/common/rich-text.scalar.ts

@@ -1,6 +1,6 @@
 import { applyDecorators } from '@nestjs/common';
 import { ObjectType } from '@nestjs/graphql';
-import { setToStringTag } from '@seedcompany/common';
+import { type Nil, setToStringTag } from '@seedcompany/common';
 import { markSkipClassTransformation } from '@seedcompany/nest';
 import { IsObject } from 'class-validator';
 import { createHash } from 'crypto';
@@ -82,23 +82,19 @@ export const RichTextField = (options?: OptionalFieldOptions) =>
     OptionalField(() => RichTextScalar, {
       optional: false,
       ...options,
-      transform: (value) => {
-        const doc = RichTextDocument.fromMaybe(value);
-        if (doc) {
-          return doc;
+      transform: (prev) => (value) => {
+        const doc: RichTextDocument | Nil = prev(
+          RichTextDocument.fromMaybe(value),
+        );
+        if (doc == null && !options?.nullable && !options?.optional) {
+          // Should never _really_ get here.
+          // UI should understand & send null instead of an empty document.
+          // Would prefer this to be done with validators.
+          // But I believe this needs `null`s to be validated.
+          // skipMissingProperties -> skipUndefinedProperties
+          throw new InputException('RichText must be given');
         }
-        if (options?.nullable) {
-          return null;
-        }
-        if (options?.optional) {
-          return undefined;
-        }
-        // Should never _really_ get here.
-        // UI should understand & send null instead of an empty document.
-        // Would prefer this to be done with validators.
-        // But I believe this needs to `null`s to be validated.
-        // skipMissingProperties -> skipUndefinedProperties
-        throw new InputException('RichText must be given');
+        return doc;
       },
     }),
     IsObject(),

src/common/sensitivity.enum.ts

@@ -27,7 +27,11 @@ export const SensitivitiesFilterField = (options?: ListFieldOptions) =>
     ...options,
     optional: true,
     empty: 'omit',
-    transform: (value) =>
+    transform: (prev) => (raw) => {
+      const value = prev(raw);
       // If given all options, there is no need to filter
-      !value || value.length === Sensitivity.values.size ? undefined : value,
+      return !value || value.length === Sensitivity.values.size
+        ? undefined
+        : value;
+    },
   });

src/components/partnership/dto/list-partnership.dto.ts

@@ -20,9 +20,13 @@ export abstract class PartnershipFilters {
   @ListField(() => PartnerType, {
     optional: true,
     empty: 'omit',
-    transform: (value) =>
+    transform: (prev) => (raw) => {
+      const value = prev(raw);
       // If given all options, there is no need to filter
-      !value || value.length === PartnerType.values.size ? undefined : value,
+      return !value || value.length === PartnerType.values.size
+        ? undefined
+        : value;
+    },
   })
   readonly types?: readonly PartnerType[];
 }