feat(schematype): add validators, path, isRequired to public AP…

…I and TypeScript types

Fix #11139

index.d.ts

@@ -3252,9 +3252,15 @@ declare module 'mongoose' {
     /** String representation of what type this is, like 'ObjectID' or 'Number' */
     instance: string;
 
+    /** True if this SchemaType has a required validator. False otherwise. */
+    isRequired?: boolean;
+
     /** The options this SchemaType was instantiated with */
     options: AnyObject;
 
+    /** The path to this SchemaType in a Schema. */
+    path: string;
+
     /**
      * Set the model that this path refers to. This is the option that [populate](https://mongoosejs.com/docs/populate.html)
      * looks at to determine the foreign collection it should query.
@@ -3288,6 +3294,9 @@ declare module 'mongoose' {
     /** Declares an unique index. */
     unique(bool: boolean): this;
 
+    /** The validators that Mongoose should run to validate properties at this SchemaType's path. */
+    validators: { message?: string; type?: string; validator?: Function }[];
+
     /** Adds validator(s) for this document path. */
     validate(obj: RegExp | Function | any, errorMsg?: string,
       type?: string): this;

lib/schematype.js

@@ -128,6 +128,51 @@ function SchemaType(path, options, instance) {
 
 SchemaType.prototype.OptionsConstructor = SchemaTypeOptions;
 
+/**
+ * The path to this SchemaType in a Schema.
+ *
+ * ####Example:
+ *     const schema = new Schema({ name: String });
+ *     schema.path('name').path; // 'name'
+ *
+ * @property path
+ * @api public
+ * @memberOf SchemaType
+ */
+
+SchemaType.prototype.path;
+
+/**
+ * The validators that Mongoose should run to validate properties at this SchemaType's path.
+ *
+ * ####Example:
+ *     const schema = new Schema({ name: { type: String, required: true } });
+ *     schema.path('name').validators.length; // 1, the `required` validator
+ *
+ * @property validators
+ * @api public
+ * @memberOf SchemaType
+ */
+
+SchemaType.prototype.validators;
+
+/**
+ * True if this SchemaType has a required validator. False otherwise.
+ *
+ * ####Example:
+ *     const schema = new Schema({ name: { type: String, required: true } });
+ *     schema.path('name').isRequired; // true
+ *
+ *     schema.path('name').required(false);
+ *     schema.path('name').isRequired; // false
+ *
+ * @property isRequired
+ * @api public
+ * @memberOf SchemaType
+ */
+
+SchemaType.prototype.validators;
+
 /*!
  * ignore
  */