add docs and test coverage for maps

Author: vkarpov15

test/types/schema.test.ts

@@ -1693,7 +1693,11 @@ async function gh14451() {
         subdocProp: Date
       })
     },
-    docArr: [{ nums: [Number], times: [{ type: Date }] }]
+    docArr: [{ nums: [Number], times: [{ type: Date }] }],
+    myMap: {
+      type: Map,
+      of: String
+    }
   });
 
   const Test = model('Test', exampleSchema);
@@ -1706,6 +1710,7 @@ async function gh14451() {
     subdoc?: {
       subdocProp?: string | undefined | null
     } | null,
-    docArr: { nums: number[], times: string[] }[]
+    docArr: { nums: number[], times: string[] }[],
+    myMap?: Record<string, string> | null | undefined
   }>({} as TestJSON);
 }

types/index.d.ts

@@ -706,6 +706,9 @@ declare module 'mongoose' {
     [K in keyof T]: FlattenProperty<T[K]>;
   };
 
+  /**
+   * Converts any Buffer properties into mongodb.Binary instances, which is what `lean()` returns
+   */
   export type BufferToBinary<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends Buffer
       ? mongodb.Binary
@@ -718,6 +721,9 @@ declare module 'mongoose' {
               : BufferToBinary<T[K]>;
   } : T;
 
+  /**
+   * Converts any Buffer properties into { type: 'buffer', data: [1, 2, 3] } format for JSON serialization
+   */
   export type BufferToJSON<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends Buffer
       ? { type: 'buffer', data: number[] }
@@ -730,6 +736,9 @@ declare module 'mongoose' {
               : BufferToBinary<T[K]>;
   } : T;
 
+  /**
+   * Converts any ObjectId properties into strings for JSON serialization
+   */
   export type ObjectIdToString<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends mongodb.ObjectId
       ? string
@@ -742,6 +751,9 @@ declare module 'mongoose' {
               : ObjectIdToString<T[K]>;
   } : T;
 
+  /**
+   * Converts any Date properties into strings for JSON serialization
+   */
   export type DateToString<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends NativeDate
       ? string
@@ -754,6 +766,9 @@ declare module 'mongoose' {
               : DateToString<T[K]>;
   } : T;
 
+  /**
+   * Converts any Mongoose subdocuments (single nested or doc arrays) into POJO equivalents
+   */
   export type SubdocsToPOJOs<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends NativeDate
       ? string