[@types/hapi__joi]: implement validate value return types (#41788)

types/hapi__joi/hapi__joi-tests.ts

@@ -955,6 +955,19 @@ schema = Joi.link(str);
     }
 }
 
+// --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
+// validate result types
+{
+    const _boolTypeTest: boolean = Joi.boolean().validate(true).value;
+    const _numberTypeTest: number = Joi.number().validate(1337).value;
+    const _stringTypeTest: string = Joi.string().validate('hello world').value;
+    const _symbolTypeTest: symbol = Joi.symbol().validate(Symbol('hello world')).value;
+    const _arrayTypeTest: number[] = Joi.array<number>().items(Joi.number()).validate([1, 2, 3]).value;
+    const _objectTypeTest: { key: string } = Joi.object<{ key: string }>({ key: Joi.string() }).validate({}).value;
+    const _dateTypeTest: Date = Joi.date().validate(new Date()).value;
+    const _alternativeType: number | string = Joi.alternatives<number | string>(Joi.number(), Joi.string()).validate(1).value;
+}
+
 // --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
 
 schema = Joi.compile(obj);

types/hapi__joi/index.d.ts

@@ -20,6 +20,7 @@
 //                 Anand Chowdhary <https://github.com/AnandChowdhary>
 //                 Miro Yovchev <https://github.com/myovchev>
 //                 David Recuenco <https://github.com/RecuencoJones>
+//                 Stefan-Gabriel Muscalu <https://github.com/legraphista>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
 
@@ -614,11 +615,11 @@ declare namespace Joi {
 
     type ValidationErrorFunction = (errors: ValidationErrorItem[]) => string | ValidationErrorItem | Error;
 
-    interface ValidationResult {
+    interface ValidationResult<T = any> {
         error: ValidationError;
         errors: ValidationError;
         warning: ValidationError;
-        value: any;
+        value: T;
     }
 
     interface CreateErrorOptions {
@@ -752,10 +753,11 @@ declare namespace Joi {
         /**
          * Runs internal validations against given value.
          */
-        $_validate(value: any, state: State, prefs: ValidationOptions): ValidationResult;
+        // tslint:disable-next-line:no-unnecessary-generics
+        $_validate<T = any>(value: any, state: State, prefs: ValidationOptions): ValidationResult<T>;
     }
 
-    interface AnySchema extends SchemaInternals {
+    interface AnySchema<TSchema = any> extends SchemaInternals {
         /**
          * Flags of current schema.
          */
@@ -1080,12 +1082,14 @@ declare namespace Joi {
         /**
          * Validates a value using the schema and options.
          */
-        validate(value: any, options?: ValidationOptions): ValidationResult;
+        // tslint:disable-next-line:no-unnecessary-generics
+        validate<T = TSchema>(value: any, options?: ValidationOptions): ValidationResult<T>;
 
         /**
          * Validates a value using the schema and options.
          */
-        validateAsync(value: any, options?: AsyncValidationOptions): Promise<any>;
+        // tslint:disable-next-line:no-unnecessary-generics
+        validateAsync<T = TSchema>(value: any, options?: AsyncValidationOptions): Promise<T>;
 
         /**
          * Same as `rule({ warn: true })`.
@@ -1145,7 +1149,7 @@ declare namespace Joi {
         localize?(...args: any[]): State;
     }
 
-    interface BooleanSchema extends AnySchema {
+    interface BooleanSchema extends AnySchema<boolean> {
         /**
          * Allows for additional values to be considered valid booleans by converting them to false during validation.
          * String comparisons are by default case insensitive,
@@ -1168,7 +1172,7 @@ declare namespace Joi {
         truthy(...values: Array<string | number>): this;
     }
 
-    interface NumberSchema extends AnySchema {
+    interface NumberSchema extends AnySchema<number> {
         /**
          * Specifies that the value must be greater than limit.
          * It can also be a reference to another field.
@@ -1235,7 +1239,7 @@ declare namespace Joi {
         unsafe(enabled?: any): this;
     }
 
-    interface StringSchema extends AnySchema {
+    interface StringSchema extends AnySchema<string> {
         /**
          * Requires the string value to only contain a-z, A-Z, and 0-9.
          */
@@ -1400,7 +1404,7 @@ declare namespace Joi {
         uuid(options?: GuidOptions): this;
     }
 
-    interface SymbolSchema extends AnySchema {
+    interface SymbolSchema extends AnySchema<symbol> {
         // TODO: support number and symbol index
         map(iterable: Iterable<[string | number | boolean | symbol, symbol]> | { [key: string]: symbol }): this;
     }
@@ -1424,7 +1428,7 @@ declare namespace Joi {
 
     type ComparatorFunction = (a: any, b: any) => boolean;
 
-    interface ArraySchema extends AnySchema {
+    interface ArraySchema<TArrayValueSchema = any> extends AnySchema<TArrayValueSchema[]> {
         /**
          * Verifies that an assertion passes for at least one item in the array, where:
          * `schema` - the validation rules required to satisfy the assertion. If the `schema` includes references, they are resolved against
@@ -1500,7 +1504,7 @@ declare namespace Joi {
         matches: SchemaLike | Reference;
     }
 
-    interface ObjectSchema<TSchema = any> extends AnySchema {
+    interface ObjectSchema<TSchema = any> extends AnySchema<TSchema> {
         /**
          * Defines an all-or-nothing relationship between keys where if one of the peers is present, all of them are required as well.
          *
@@ -1636,7 +1640,7 @@ declare namespace Joi {
         length(limit: number | Reference): this;
     }
 
-    interface DateSchema extends AnySchema {
+    interface DateSchema extends AnySchema<Date> {
         /**
          * Specifies that the value must be greater than date.
          * Notes: 'now' can be passed in lieu of date so as to always compare relatively to the current date,
@@ -1706,7 +1710,7 @@ declare namespace Joi {
         maxArity(n: number): this;
     }
 
-    interface AlternativesSchema extends AnySchema {
+    interface AlternativesSchema<TAlternativesSchema = any> extends AnySchema<TAlternativesSchema> {
         /**
          * Adds a conditional alternative schema type, either based on another key value, or a schema peeking into the current value.
          */
@@ -1877,7 +1881,8 @@ declare namespace Joi {
         /**
          * Generates a schema object that matches an array data type.
          */
-        array(): ArraySchema;
+        // tslint:disable-next-line:no-unnecessary-generics
+        array<T>(): ArraySchema<T>;
 
         /**
          * Generates a schema object that matches a boolean data type (as well as the strings 'true', 'false', 'yes', and 'no'). Can also be called via bool().
@@ -1933,8 +1938,10 @@ declare namespace Joi {
         /**
          * Generates a type that will match one of the provided alternative schemas
          */
-        alternatives(types: SchemaLike[]): AlternativesSchema;
-        alternatives(...types: SchemaLike[]): AlternativesSchema;
+        // tslint:disable-next-line:no-unnecessary-generics
+        alternatives<T = any>(types: SchemaLike[]): AlternativesSchema<T>;
+        // tslint:disable-next-line:no-unnecessary-generics
+        alternatives<T = any>(...types: SchemaLike[]): AlternativesSchema<T>;
 
         /**
          * Alias for `alternatives`