I'm trying to find a nice way to validate a body using DTO (using the brilliant class-validator and class-transformer libraries). It works really well, even for nested structures but in my case I'd like to have the body property based on some conditions.
Example that will probably help to understand:
Let's imagine my body should always have selectedCategory.
Based on that field, the content could either be from category 1, which contains prop1 OR from category 2, which contains prop2.
I do not want to allow a null for both of them, I really want to have to either have prop1 defined or prop2 based on the selectedCategory.
I think that I could use a pipe, but then how can I specify the correct DTO to use?
I've built a "base" class with all the common properties and few other classes that inherit from it.
I could instantiate the pipe manually based on the property selectedCategory, that'd be ideal but I have no clue what to pass as a second argument of the pipe (metadata).
Thanks for your help.
Have you tried using groups?
Instead of having multiple DTOs, you just create one DTO. Every property is assigned to one or multiple groups:
#Min(12, {groups: ['registration', 'update']})
age: number;
#Length(2, 20, {groups: ['registration']})
name: string;
You can then conditionally pass the groups to class transformer / validator:
#Injectable()
export class ConditionalValidationPipe implements PipeTransform {
async transform(entity: any, metadata: ArgumentMetadata) {
// Dynamically determine the groups
const groups = [];
if (entity.selectedCategory === 1) {
groups.push('registration');
}
// Transform to class with groups
const entityClass = plainToClass(EntityDto, entity, { groups })
// Validate with groups
const errors = await validate(entityClass, { groups });
if (errors.length > 0) {
throw this.createError(errors);
}
return entityClass;
}
}
Have you tried the ValidateIf statement?
You can have multiple validations for props1 or props2 and apply them if selectedCategory is "category 1" or "category 2" accordingly.
Related
I don't even think I've got a proper question so I apologize greatly.
I am consuming a 3rd party API and to update or create records, one of the fields is the entity type.
For example, here is my CreateOrganizationDTO:
export class CreateOrganizationDto {
#ApiProperty({
description: "The entity type. Only 'organization' is allowed.",
example: "organization",
})
#IsNotEmpty()
readonly #type: string; <-- this
...
I'm not sure how to properly handle the # character. I've tried different versions of '#type' or ['#type']. Clearly, neither are correct. I'm also not sure how to send that data through my service. For example:
// MyService.ts
const {name, #type, active} = updateOrganizationDto;
organization.name = name;
organization.#type = #type; <-- not going to work :(
organization.active = active;
...
What is the proper way to "escape" this # throughout my application? Thank you for any suggestions!
I have NestJS API, which has a PATCH endpoint for modifying a resource. I use the class-validator library for validating the payload. In the DTO, all fields are set to optional with the #IsOptional()decorator. Because of that, if I send an empty payload, the validation goes through and then the update operation errors.
I am wondering if there is a simple way to have all fields set to optional as I do and at the same time make sure that at least one of them is not empty, so the object is not empty.
Thanks!
I don't know if it is possible using DTO.
For that purpose I use Pipes. Like this:
Injectable()
export class ValidatePayloadExistsPipe implements PipeTransform {
transform(payload: any): any {
if (!Object.keys(payload).length) {
throw new BadRequestException('Payload should not be empty');
}
return payload;
}
}
I'm validating my DTOs with the class-validator package. I enabled the transformation via
app.useGlobalPipes(
new ValidationPipe({
transform: true,
}),
);
in my main.ts file as described in the docs
https://docs.nestjs.com/techniques/validation#transform-payload-objects
I have a optional configuration field in my DTO. This field should be transformed to an empty object if it doesn't exist. The transformation decorator is described here
https://docs.nestjs.com/techniques/serialization#transform
I was hoping to come up with this solution:
export class MyDTO {
#IsObject()
#IsOptional()
#Transform(configuration => configuration || {})
public configuration: object;
}
When I call my API route
#Post()
public create(#Body() myDTO: MyDTO): void {
console.log(myDTO);
}
with an empty body, so without the field configuration my MyDTO instance is
{}
although I would expect it to be
{
configuration: {}
}
What is wrong or what am I missing? I tried to debug the code and it never hits the transformation function. So the #Transform doesn't trigger.
Update
It seems I have to do this
#IsObject()
#IsOptional()
#Transform(configuration => configuration || {}) // will be used if the field exists
public configuration: object = {}; // will be used if the field doesn't exist
The initial value will be used if you pass in an empty body. The transformation only runs if you pass in the field but assign a value like null to it.
Gonna go ahead n put this here too: why not just let typescript manage the default value with setting the value like
export class MyDTO {
#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.
Looks like there is more discussion about solutions here.
I'm trying to write a custom validator that will check if an entity exists in the database, using OrmLite. The problem is that the type arguments for IRuleBuilder can no longer be inferred from usage.
I have to write the method call like this:
RuleFor(r => r.Id).Exists<DtoName, int, EntityName>()
But I want to write it like this:
Rulefor(r => r.Id).Exists<EntityName>()
This happens because IRuleBuilder has two type parameters and the method is an extension method. Is there a smart, fluent way to design this and make the function call preferably like the second version?
Here is code for my extension method and my validator:
public static class AbstractValidatorExtensions
{
public static IRuleBuilderOptions<T, TProperty> Exists<T, TProperty, U>(this IRuleBuilder<T, TProperty> ruleBuilder)
{
return ruleBuilder.SetValidator(new EntityExistsValidator<U>());
}
}
public class EntityExistsValidator<T> : PropertyValidator
{
public EntityExistsValidator() : base("Entity does not exist") {}
protected override bool IsValid(PropertyValidatorContext context)
{
return HostContext.Resolve<Repository>()
.Exists<T>((int)context.PropertyValue);
}
}
My experience with FluentValidation is that you’re trying to push more and more logic into validators. I would not do this as it adds too much complexity. My rule of thumb is to validate discrete property values only. Example: I would just use FluentValidation to check if property int Id is 0 or greater than 0. The check if the entity already exists I would move to another service (often called “the business logic”).
You'll need to a Custom Validator for custom validation to access dependencies, something like:
RuleFor(x => x.Id)
.Must(id =>
{
using (var db = HostContext.AppHost.GetDbConnection(base.Request))
{
return !db.Exists<EntityName>(x => x.Id == id);
}
})
.WithErrorCode("AlreadyExists")
.WithMessage("...");
I'd also consider just doing validation that use dependencies in your Services instead:
if (Db.Exists<EntityName>(x => x.Id == request.Id))
throw new ArgumentException("Already Exists", nameof(request.Id));
I am writing a NestJS application. Some of the endpoints support sorting e.g. http://127.0.0.1:3000/api/v1/members?sort=-id&take=100 Which means sort by id descending.
This parameter arrives as a #Query parameter and is passed to my service. This service transforms it into an object which is used by TypeORM:
{
id: 'DESC'
}
I don't want to call this conversion method manually every time I need sorting.
I've tried an intercepter but this one could not easily change the request parameters into the desired object.
A pipe worked but then I still need to add #Query(new SortPipe()) for every endpoint definition.
Another option is in the repository itself. The NestJS documentation is very well written, but misses guidance in where to put what.
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.
Pipes are probably the easiest way to accomplish this. Instead of adding your pipe for every endpoint definition you can add a global pipe that will be called on every endpoint. In your main.ts:
async function bootstrap() {
...
app.useGlobalPipes(new SortPipe());
...
}
You can then create a pipe like this:
import { PipeTransform, Injectable, ArgumentMetadata } from '#nestjs/common';
#Injectable()
export class SortPipe implements PipeTransform {
transform(value: any, metadata: ArgumentMetadata) {
const { type } = metadata;
// Make sure to only run your logic on queries
if (type === 'query') return this.transformQuery(value);
return value;
}
transformQuery(query: any) {
if (typeof query !== 'object' || !value) return query;
const { sort } = query;
if (sort) query.sort = convertForTypeOrm(sort);
return query;
}
}
If you do not want sort value on ALL endpoints to be automatically converted, you can pass custom parameter to #Query(), for example #Query('sort'). And then:
transform(value: any, metadata: ArgumentMetadata) {
const { type, data } = metadata;
// Make sure to only run your logic on queries when 'sort' is supplied
if (type === 'query' && data === 'sort') return this.transformQuery(value);
return value;
}