Nestjs transform string to number

Nestjs transform string to number. There are multiple ways of calling this method. prototype object, takes an integer or floating point number and converts it into a String type. . Now, I have another Controller that would allow you to add multiple services, but it should be "keyed" by a specific string, something with the shape of: Feb 10, 2020 ยท Whilst studying NestJS I encountered an issue, I have the following DTO: export default class SearchNotesDto { query: string; createdAfter: Date; createdBefore: Date; } Which I wish to get when a GET request is made to an endpoint, which is handled by the following function in my controller: May 16, 2022 ยท Logging the data, the intended boolean doDelete is still a string and wasn't transformed to its native boolean type. Jun 2, 2022 ยท Validating the date with Joi is also straightforward. email; user. env file in the root directory with the content. For example, if the user passes 2/31/2029, it will be converted to 3/3/2029. this works well for almost all values I wish to put in the body. e. Sep 15, 2021 ยท As you mentioned in the comments, you have to use @IsNumber (numberValdiatorOptions, { each: true }) which is briefly mentioned at high level here. Your final bootstrap () function should look like this: import { ClassSerializerInterceptor } from '@nestjs/common'; import { ValidationPipe } from '@nestjs/common'; Mar 22, 2019 ยท Unary Operator By adding a + sign before a String, it will be converted into a number if it follows the right format. parseInt will return an integer found in the beginning of the string. The idea is to convert this string to an object, validate it and pass to controller as an object ValidationPipe set up: app. id. Nov 7, 2019 ยท You signed in with another tab or window. Improve this question. As you can see from the CreatePostDto above, the tags array of strings works perfectly. ยท. The problem is with the returned data. Reload to refresh your session. And, I'd like to search a list of between 2020 ~ 2025 year. Oct 12, 2023 ยท So what the pipe does with your options is it sees that the value coming in is a string, but typescript says it's a number, class-transformer recognizes this and transforms the string to a number, even an "invalid" one because that's how JS works,and then the pipe sees that transform: true is set so it returns the transformed value. @Type ( () => Number) Let's take an example URL address with few query parameters: https://awesomesite. This is a very intentional design choice. , unary plus) involve implicitly coercing the type of the string to a number. 2"; console. However Apr 29, 2023 ยท By Expanding your dto (change type of weight_per_pallet from number to number | string for receiving number and string types), and using pipe transform, you can convert string to number automatically. I am using Nest Serialization to transform api response. Jul 20, 2022 ยท I'm trying parse ISo8601String to Date in Nest JS through DTO. If you just want to test the transformations, you can assert after this statement. pricing. All of the tricks in the other answers (e. Feb 10, 2020 ยท endpoints: {. Remember, that only the first number in the string will be returned. Gonna go ahead n put this here too: why not just let typescript manage the default value with setting the value like. There are two main ways to convert a string to a number in JavaScript. As the multipart-form conversion doesn't happen automatically. Posting a solution for using class-transformer withe mongoose below which can be helpful for others, it uses custom interceptor that you can see in the nest documentation. then, change plain json into DTO by using plainToClass of class-transformer like below. To convert a string in the form of float to a number we use the parseFloat () function and to convert strings that do not have decimal to a number, the parseInt () function is used. The thousands separator and decimal point may not be obtained in the JS standard. In the above example, we specified the id type as a number (in the method signature). Dec 4, 2021 ยท 2. getTime(); } Apr 19, 2020 at 10:01. ts: import { Transform, TransformFnParams } from "class-transformer"; export function ToBoolean(): (target: any, key: string) => void {. Apr 12, 2021 ยท Simple solution โ€“ use @Type () decorator from class-transformer library, and declare numeric field as Number. results;i++){ obj. js. You switched accounts on another tab or window. The first argument of parseInt must be a string. lookup is actually returned as a string. This is done using @Type decorator. Important is, you must type app. to-boolean. dto. My database entities look like: class MyEntity { id: string; property1: string; property2: string; } but my API needs to output something like The . $ npm i --save @nestjs/config. js project, where in the request body we expect an object, one property of this object contains stringified JSON value. This is what I have so far: Jul 29, 2019 ยท In the documentation, Using this built-in method, when a request handler returns a JavaScript object or array, it will automatically be serialized to JSON. The Javascript function getTime() returns the number of milliseconds from the same specific date til the date you specified. Using ValidationPipe. It's not converting to false as we implied via Sep 7, 2021 ยท Class-Validator works based on classes. " Jun 28, 2022 ยท To ensure errors on validation when extra properties are sent in, you need to make use of the forbidNonWhitelisted option in the ValidaitonPipe. 000} In Nest js, I receive the data and it's transform by: @ From number to currency string is easy through Number. ObjectID. Dec 11, 2019 ยท You can pass an instance of the ValidationPipe instead of the class, and in doing so you can pass in options such as transform: true which will make class-validator and class-transformer run, which should pass back the transformed value. You can also do the same thing explicitly with the Number function. localValues, {toPlainOnly: true}) public foobar: ExchangeableMoney; In your controller: Mar 10, 2022 ยท That might take up to a minute. Multiply by 1 If a String is multiplied by the primitive number 1, the string will become a number. PORT = 3000. status: boolean. I. fromHexString If your schema expects the property to be of type ObjectId, the conversion is implicit, at least this seems to be the case in 4. (nested property postalAddress must be either object or array). data. toString () method, the number will be parsed and converted to that base number: let a = 20. so lets see this with examples. Everywhere I define it as a number. ts. You must use a custom value Transformation that converts the value to a boolean when it is a string. I tried DTOs. number. log(createProductDto. Oct 1, 2021 ยท If you intend to keep the @IsDateString decorator, you'll run into new errors when you use it alongside the @Transform decorator ( @Transform ( ( { value }) => new Date (value)) ). Enough of the theory, let's jump into the code: @Get(':_id') async findUserById(@ Param('_id',ParseIntPipe) id:number):Promise<UserDto>{ return this. However, it is passed as a string which makes it very complicated to handle. Injectable, NestInterceptor, ExecutionContext, CallHandler, } from '@nestjs/common'; import { Observable } from 'rxjs'; import { map } from 'rxjs/operators'; Nov 20, 2021 ยท Nestjs comes with 8 built in pipes out of which 6 are transformation pipes and 1 is a validation pipe. Jul 4, 2022. As a result Mar 2, 2019 ยท I am a freshman in Nest. Feb 27, 2021 ยท given your JSON, simply manipulate it to change the date to a timestamp: and it looks like you have a number of elements in your JSON so: var myDate = new Date(); for(var i=0;i<obj. Request payloads that come into the server are just plain JSON objects to start off with. So, if you divide the result of your function by number 1000 you will get the Unix timestamp and convert from milliseconds to seconds. com/users?country=6&name=joe. parse(data. Feb 23, 2020 ยท 3. import { BadRequestException, Injectable } from '@nestjs/common'; import { ConfigService } from '@nestjs/config'; import { Twilio } from 'twilio'; Jul 26, 2022 ยท 0. I send a json with the date's string like: {lunMIni: 1001-01-01 00:00:00. import { IsOptional, IsInt, Min } from 'class-validator'; import { Transform } from 'class-transformer'; export class Jan 27, 2020 ยท Great resonse from @Riajul Islam! As an addition to his answer, if you want to store bigint in PrimaryGeneratedColumn, you should you the following: @PrimaryGeneratedColumn( 'increment', {type: 'bigint'} ) id: number; Just add { bigNumberStrings: false } to TypeORM's configuration, such as: bigNumberStrings: false, Oct 10, 2019 ยท Bug Report Current behavior I have a controller that needs to recive data from the request query and I want to put that data into a DTO using @query() but it does not properly transform the DTO to the target interface Input Code import { Nov 11, 2022 ยท nestJS class-validator: property is string: check the value is between 100 to 5000 i need to validate dto property that validate string number between 100 and 5000 node. then nest will take dto and turn it to the json and send it back as response. email = dto. Our controller would probably look like this: Jul 4, 2022 ยท 7 min read. For this example, I select NPM. whitelist: true, Aug 11, 2020 ยท @kamilmysliwiec I'm curious why we would need to use the "implicit conversion" (i. 1. You can view this stackblitz with a working configuration. Create a . service. transform: true automatically transforms input data to the class May 6, 2021 ยท NestJs we cannot directly convert int to int64 we need to use some libraries for conversion the issue with libraries is it converts the int into BigInt but it appends 'n' at the end can you suggest or provide alternative how to further proceed. When I try to use only the decorator IsNumber() and pass a body with a empty property, validation fails. Jun 25, 2020 ยท You can perform additional data transformation using the @Transform () decorator. toString () method that belongs to the Number. And my code as below @Get('findByFilter/:params') async findByFilter(@Query() query): Promise<Article[]> { } I have used postman to test this router htt Sep 12, 2018 ยท 0. useGlobalPipes(new ValidationPipe({ transform: true, whitelist: true })) on your main. The date() validator checks if the passed data is of type date. If I use mysql and decimal it does correctly return number. password); // createPasswordHash fucntion needs to be defined. @UsePipes(new ValidationPipe({transform: true})) @Get('test_input') async testInput(@Query() data: UserRoleCreateDto): Promise<any> {. How to handle unexpected data from the post request body in NestJS. id: string. In my service component need use BigNumber's functions but I can't because this amount behaves like a string. validate (number); // error: currently gets passed as a string} I know I can use parseInt(code) but i am wondering if there is a more elegant way of specifying to the injector to return the param as a number. This is my CreatePostDto: Apr 20, 2021 ยท 1 Answer. 229Z" Any idea of how to easily configure this without having to make my API objects hold a "number" or "string" (aka, manually converting it) instead of a Date? Introduction. Jul 19, 2021 ยท Now, we need to create a way for the users to send the verification code back to our API. let str1:string = "102. I construct it like this: Dec 8, 2018 ยท Try specifying the nested type with @Type: import { Type } from 'class-transformer'; export class CurrencyDTO {. ts and do the mapping + hashing of the password in there. const user = new User(); user. In this particular question the thousands separator is a white space " "but in many cases it can be a period ". Milestone. Swagger is sending the boolean as a string. There is an extra pipe which sets a default value, known as the DefaultValuePipe. However, it returns really crypic result. public async getAll(): Promise<ItemDTO[]> {. Jun 29, 2023 ยท If you need to allow explicit null values, you will have to create a custom validator. Example 3: Numbers can be of type float or int. A simple workaround, but every string different than true, results in false. if the content type is multipart-form then transform for the nested object doesn't work. parse function to convert a few invalid dates to valid dates. Nov 14, 2019 ยท Here, myBodyObject is your plain object that you created for test, like: const myBodyObject = { attribute1: 1, subDto: { name: 'Vincent' } } The plainToInstance () function also applies all the transformations that you have in your DTO. When you are trying to transform objects that have nested objects, it's required to known what type of object you are trying to transform. new ValidationPipe({. Connect and share knowledge within a single location that is structured and easy to search. Improve this answer. One way is to parse it and the other way is to change its type to a Number. So, I tried to include the decorator IsNotEmpty() too, but this is not working apparently, because if I pass a empty property, the flow follows. Feb 26, 2018 ยท Nestjs ValidationPipe({transform: true}) does not transform string to number for request body. js server-side applications. nestjs. Learn more about Teams Feb 12, 2020 ยท If I am understanding what you are doing with your controller response and your overall interceptor response, what you can do is something similar: import {. This is an appropriate place to provide rules for transforming and sanitizing the data to be returned to the client. password = createPasswordHash(dto. To force them to resolve to numbers you can add @Type ( () => Number) so that class-transformer turns them into a number and class-validator then reads the correct value. Using postgres, when I retrieve a non-integer number from the database it's always returned as string instead of a number. description: string. I agree with your solution, but if you have to develop the "cable update" method, you need to modify toEntity (dto: Partial<CableDto>) in order to retrieve the Cable by ID specified by CableDto. If you apply the ParseIntPipe to the id param, it will only transform id but not the property id of params, here it will stay a string. So you need to inject the repository into the CableDto, but CableDto is simply a plain class. As example in docs say: import { IsEmail, IsNotEmpty } from 'class-validator'; // 'class' export class CreateUserDto { // notice class @IsEmail() email: string; @IsNotEmpty() password: string; } Update #1 - tell validator to try to make implicit conversion 2. BSONPure. prototype. I am running into an issue with supertest when a query parameter ({count: false}) is passed NestJS treats it as a string because the dto validation is not being executed. If you have any transformations in your DTO, like trimming spaces of the Jul 5, 2011 ยท I couldn't resolve this method (admittedly I didn't search for long) mongoose. lookup) Feb 20, 2019 ยท When using @UseInterceptors(ClassSerializerInterceptor) like it is explained in the Documentation here. Try something like this: import * as bodyParser from 'body-parser'; async function bootstrap() {. NestJS aims to improve code readability and modularity by heavily leveraging decorators for various kinds of cross-cutting concerns. For example, the following construct returns the name property of the RoleEntity instead of returning the whole object. userService Aug 27, 2020 ยท @Expose({ name: 'picklist_name' }) picklistName: string; Built-in ClassSerializerInterceptor Instead of defining the toJSON method yourself, you can use the built-in ClassSerializerInterceptor to automatically serialize your entities when returning them from a controller method, see this answer . log(createProductDto); console. export class CreateProductDto { readonly pricing: { readonly list: number; } } async create(@Body() createProductDto: CreateProductDto) { console. answered Sep 15, 2021 at 21:39. const app = await NestFactory. list); } Mar 27, 2020 ยท Convert the test object to the type of DTO. ts line 35), but then the validation doesn't work in the nested Sep 23, 2021 ยท How can I handle the validation of an array of numbers in form data? Because I am passing data in a form-data format, I can't validate an array of numbers Actually, I don't know how to do it. Apr 2, 2019 ยท 1 Answer. @IsInt() should attempt to transform a string to an Nov 7, 2021 ยท I dont know why, but but column values always get returned as strings instead of decimals and I dont know how to fix this issue. The use of @IsDateString implies that you expect a date string in ISO8601 format as input. That code is for using Oct 14, 2019 ยท See NestJS docs - Auto Validation NestJS docs - Payload transforming. For single query param usage, you can play with this example: import { ArgumentMetadata, BadRequestException, Injectable, PipeTransform } from '@nestjs/common'; type TOptional<T> = T | undefined; @Injectable() export class ValidateEnum<T extends Record<string, unknown>> implements PipeTransform<T> {. Sep 16, 2017 ยท ) codes (@ Param ("code") code: number) {return ValidationService. mongo. However the reverse seems to be a common problem. Since Typescript does not have good reflection abilities yet, we should implicitly specify what type of object each property contain. So there are two options you have: Create user. Lets say we have an album with photos. g. That might take up to a minute. parseInt() The base can be defined by adding prefixes to the numbers we want to parse: No prefix - If there isn't a prefix, the Jun 5, 2022 ยท I'm new in nest js. This article focuses on techniques for the implementation of secure and error-proof APIs as much as it could be achieved by controlling APIโ€™s input and output payloads. lookup: JSON. Since I use Visual Studio Code, I gonna open the project by typing: $ cd nest-transform-query. { lookup: '["s1", "s2"]' } Either fix the api to send an array of strings or try this. Apr 5, 2020 ยท For people trying to follow nestjs documentation & using mongoose but ClassSerializerInterceptor not working. You have forgot to add @validateNested decorator. I use dto technic. export class ProductEntity {. const data = { lookup: '["s1", "s2"]' } const parsedData = {. product. Parsing Mar 23, 2021 ยท When I send a JavaScript Date() object via a put request to my Nest backend I assume that the date format stays like it is. The problem here is that the data is nested in an array. Instead, you can use class-transformer to transform your param to a number: @Transform(id => parseInt(id), {toClassOnly: true}) id: number; Then you use the ValidationPipe with the option transform: true: Feb 27, 2020 ยท Current behavior. This makes response handling simple: just return the value, and Nest takes care of the rest. I manually add the transform (CreateUser. Nov 21, 2022 ยท As I mentioned in the title, I want to query a string type field value by filtering it to a specific range of numbers. toLocaleString. The CLI script will ask you what package manager you want to use. For example when we have the string โ€œ384 Dec 4, 2023 ยท If you want to preform some sort of validation before turning the string into a Date you can use the @Transform () decorator with the advanced approach from class-transformer's docs and do something like. To change this behaviour, Nest has to first call plainToClass from class-validator if you're using its ValidationPipe. The issue is that @MinDate accepts an argument of type Date whereas what Feb 26, 2024 ยท The second example uses the parseFloat function to convert a string to a floating-point number. Jun 23, 2021 ยท The option transform: true will transform ie; execute the function inside @Transform decorator and replace the original value with the transformed value (val => BigInt (val) in your case). This will transform the stringified "bigint" to the primitive "bigint". It automatically calls classToPlain on the response: In your dto (with toPlainOnly): @Transform((money: ExchangeableMoney) => money. 8. TypeScript can infer the type of the variables to be number because even NaN is of type number . use(bodyparser({ options })) // for plain/text bodies. getUsers: (): UserResponseDto[] first, change Entity into plain json by using classToPlain of class-transformer. Can I apply the DTO to interfaces as well. Use plainToinstace () function from the class-transformer package: const ofImportDto = plainToInstance(OfImportDto, importInfo) This will turn your plain test object to the object of the type of your DTO, that is, OfImportDto. Javascript. only('s Dec 16, 2020 ยท @Transform(value => new BigNumber(value)) amount!: BigNumber when I remove @Transform(value => new BigNumber(value)) code start working but amount field of DTO isn't BigNumber object, just holds string with amount. Nov 26, 2019 ยท You can use this: @IsBoolean() @Transform(({ value} ) => value === 'true') public laserMode: boolean; This will transform the string into a boolean value, based on if it is 'true' or any other string. Explicit conversion # In the above section, we showed how the ValidationPipe can implicitly transform query and path parameters based on the expected type. It uses progressive JavaScript, is built with and fully supports TypeScript (yet still enables developers to code in pure JavaScript) and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming). Jun 26, 2019 ยท 4 Answers. You signed out in another tab or window. Nest is a framework for building efficient, scalable Node. create_time = myDate(obj. I expect it to slice some fields out of the data but for some reason, it shows weird result. 4. No branches or pull requests. There is nothing such as automatic mapping that comes with NestJS. Feb 24, 2020 ยท By default, NestJS use the format shown in this example: "2020-02-24T07:01:31. Nest is not compatible with plain/text and you must pass a bodyparser to your express app instead. Mar 23, 2022 ยท I'm using class-transformer (in nestjs) to convert my database entities into dto types to output from my api. I've tried this way. log (typeof str1); let num = parseFloat (str1); Jun 8, 2021 ยท There is a nest. Mar 11, 2019 ยท The . With the @Type decorator you tell class-transformer to May 1, 2023 ยท In your src/main. Follow. useGlobalPipes(. None yet. I get the desired filtered result, however while using mongodb the id is formatted in _bsontype instead of a normal string like it used to be without the interceptor like this: Is there someone who had a similar issue with converting Query parameters before they are used in NestJS, and can explain what approach is the best within NestJS? This question might look like an opinion based question, however I am looking for the way it is supposed to be done with the NestJS philosophy in mind. What's probably happening is something in your service is expecting a number and it's getting a Teams. Create a new application via NestJs CLI. Nest (NestJS) is a framework for building efficient, scalable Node. This value is of string type. It uses progressive JavaScript, is built with TypeScript and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and Dec 29, 2020 ยท I want to transform my query param from string to number. For example, sensitive data like passwords should always be excluded from the response. If a number ( base) is passed as a parameter to the . Use parseInt () function, which parses a string and returns an integer. return data; Check that you have ValidationPipe decorator and especially transform: true option, without these it doesn't work. export class MyDTO {. const isValidDate = isISO8601(value, { strict Oct 17, 2018 ยท export class ListQueryDto {@ Type (() => Number) readonly limit: number;} But this should not be required and needs to be fixed. ๐Ÿ‘ 1 miensol reacted with thumbs up emoji Aug 13, 2021 ยท 2. 0. May 18, 2020 ยท I am trying to create a DTO file to transform the values and save a Document. Development. You might have noticed that NestJS heavily relies on decorators. useGlobalPipes(new ValidationPipe({ transform: true })); should transform the types based on the decorators, i. @IsObject() @IsOptional() public configuration: object = {}; } That way, if you get a value, great, and if it isn't there, class-transform will put the correct value there. @Get() public async getChecklists(@Query(new ValidationPipe({ transform: true })) filter: ChecklistFilter Dec 29, 2020 ยท I'd like to rectify and map these properties to standard camel-cased models in our new TypeScript NestJS API so that I don't couple mismatched patterns in a legacy system to our new API and new standards, essentially using the @Transform in the DTOs as an isolation mechanism for the rest of the application. Here's how to do it with a custom validator: import { ValidatorConstraint, ValidatorConstraintInterface, ValidationArguments, registerDecorator, ValidationOptions } from 'class-validator'; @ValidatorConstraint({ name: 'IsStringOrNull', async: false }) export class IsStringOrNullConstraint implements Jan 9, 2022 ยท 1 Answer. Number Turns to String over Http Request from Angular Client to NestJS Server: I pass firstIndex: number through the params of a GET http request from my Angular client to my NestJS server. results[i]. Did tried proviiding any data like this: @Transform ( ( { value }) => { return false}) But in the controller, the data is still the same if we set the original DTO doDelete to true. test is it. In the params of my service function firstIndex: number. But sometimes, we want to cast these string types to something else like numbers, dates, or transforming them to a trimmed string, and so on. Update the app. entity. create_time). import { Module } from "@nestjs/common"; import { ConfigModule } from "@nestjs/config"; Oct 29, 2021 ยท I need to validate if value is a number and not empty. js Apr 4, 2022 ยท Output: string. create(AppModule); app. Sep 12, 2017 ยท Projects. They get stored properly in the database, but when I query using QueryBuilder, the results are shown as strings. Serialization is a process that happens before objects are returned in a network response. Share. . Sorted by: 1. I want to do a transformation for incoming request: import { IsPhoneNumber } from 'class-validator'; import { Transform } from 'class-transformer'; export class PhoneLoginDto { Jul 10, 2019 ยท 2. ts to. ts, import the ClassSerializerInterceptor from @nestjs/common and add the interceptor globally. EDIT: Updated the function inside Transform decorator to match class-transformer v0. @PrimaryGeneratedColumn() id: number; @Transform(x => new Date(x)) @Column('text') date: Date; May 1, 2023 ยท It's working great on its own, NestJS is appropriately validating the user's input if it satisfies this class when this is used as a DTO. The ValidationPipe does not work on primitive types (string, boolean, number), so you'll need to use the ParseIntPipe or something similar on the @Param () decorator to ensure you get the same kind of logic being applied. But we we ill turn it to User DTO which will have all the serialization rules. module. Feb 1, 2024 ยท Teams. Q&A for work. Install the config module. $ nest new nest-transform-query -p npm. To do that, letโ€™s create an additional method in our SmsService: sms. 7. We initialize a new NestJS project with its CLI. $ nest new application. May 20, 2019 ยท Typically you would use the built-in ClassSerializerInterceptor in combination with the ValidationPipe (with transform: true). If the first non-whitespace character of the string cannot be converted to a number, the parseInt() and parseFloat() functions return NaN (not a number). It uses progressive JavaScript, is built with TypeScript and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP Apr 11, 2023 ยท I am using JS fetch API, and to send the multiple files, I am using JS FormData object as the fetch API body, as per the NestJs documentation and this question. If you just want to strip the values you can use transform: true and whitelist: true. When it returns a string, however, Nest will send just a string without attempting to serialize it. useBodyParser method will respect the rawBody option that is passed in the application options. @ApiProperty() @IsISO8601({ strict: true, strictSeparator: true }) @Transform(({ value }) => {. Sep 15, 2017 ยท A Unix timestamp is the number of seconds from a specific date. For example, in a test table, I have row values with random year values between 2020 and 2040. 10 participants. using the type information that is provided by typescript), where my understanding is the app. Under the hood, the date validator uses the JavaScript Date. Therefore, the ValidationPipe will try to automatically convert a string identifier to a number. When grabbing it from the server side @Query ('firstIndex Both Cat and Dog must be defined as extra models using the @ApiExtraModels () decorator (at the class-level). Feb 12, 2019 ยท import { map } from 'rxjs/operators'; import { plainToClass } from 'class-transformer'; // Normally user entity goes into the interceptor and nestjs turns it into the JSON. No milestone. Nov 16, 2022 ยท Query ( @Query ()) and URL ( @Param ()) parameters always come in as strings. After this command is done you can open your project in your code editor. Learn more about Teams Jul 18, 2022 ยท Integrated ParseIntPipe to parse a string path variable and convert it to a number. Jan 28, 2022 ยท In NestJS and ExpressJS it's actually an object that contains strings as values. @ValidateNested({ each: true }) @Type(() => Data) data: Data[]; } For a nested type to be validated, it needs to be an instance of a class not just a plain data object. How to Convert a String into an Integer. Oct 27, 2022 ยท In this blog post, we will be focusing on NestJS's validation using ValidationPipe - specifically on one lesser known feature- which is the ability to not only validate input, but transform it beforehand as well, thereby combining transformation and validation of data in one go. kv qg lh ii bo yq us zh qv nn