How to properly type Prisma query results with included relations in Wasp?
Hi everyone, I'm trying out Wasp, and I have a small problem I would like share here.
model Product {
id String @id @default(uuid())
name String
description String
price Float
stockQuantity Int @default(0)
unit String
// Remove the files relation as it will be accessed from the other side
file File?
user User @relation(fields: [userId], references: [id])
userId String
createdAt DateTime @default(now())
updatedAt DateTime @updatedAt
}
model File {
id String @id @default(uuid())
createdAt DateTime @default(now())
// Make this a one-to-one relation
product Product @relation(fields: [productId], references: [id], onDelete: Cascade)
productId String @unique // Add unique constraint to ensure one-to-one relationship
name String
type String
key String
uploadUrl String
}
I have this two models, then, in one my querys, I want to get Products with Files, so I do:
export const getProducts: GetProducts<void, Product[]> = async (args, context) => {
if (!context.user) {
throw new HttpError(401)
}
return context.entities.Product.findMany({
where: { user: { id: context.user.id }},
orderBy: { createdAt: 'asc'},
include: {
file: true
}
})
};
This works great and the return object brings Product with files, however, the type definition doesn't include the file property, so I get an error in the frontend when I want to use product[n].file.
How can I fix this?4 Replies
Hi @Trujillo. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:
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To properly type Prisma query results with included relations in Wasp, you need to adjust the type annotation for your query function. The issue you're experiencing is due to the type definition not including the
file relation, even though you're including it in your Prisma query.
Here's how you can fix this:
1. First, import the necessary types from Wasp:
2. Then, modify your query function type annotation to include the file relation:
By using (Product & { file: File | null })[] as the return type, you're telling TypeScript that the result will be an array of Product objects, each potentially including a file property of type File (or null if there's no associated file).
This approach is based on the information provided in the Discord support thread where a similar issue was discussed. The solution involves explicitly defining the shape of the returned data, including the relations.
By making this change, you should be able to access product[n].file in your frontend without TypeScript errors.
Remember that this solution assumes you're using TypeScript. If you're using JavaScript, you won't need to worry about type annotations, but you'll also lose the benefits of static type checking.
Wasp Documentation on Queries provides more information on implementing and typing queries in Wasp.
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Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
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Sorry @Trujillo, I seem to be having a bit of trouble. Don't worry though, I've pinged my support and they will try to fix me up! :technologist:
Perhaps try again in 15mins?Cool. That works, thanks bot.
@kapa.ai You could also use the
satisifies here to allow Typescript to use the return value of your fn as the Output type variable for GetProductsLet me check the knowledge base for you again. One moment! :books:
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You're absolutely right! Using the
satisfies keyword is an excellent alternative approach to typing your query function in Wasp. This method allows TypeScript to infer the return type automatically based on the actual return value of your function.
Your code snippet is correct and follows the recommended practice for typing queries in Wasp when you want to include relations. Here's why this approach is beneficial:
1. It allows TypeScript to infer the correct return type, including the file relation, without you having to explicitly define it.
2. It ensures type safety while reducing the amount of manual type annotation required.
3. It's more flexible and less prone to errors when the query's return shape changes.
This approach is indeed mentioned in the Discord support thread as a preferred solution. The community member there stated:
"If don't want to define a new type for the Query's return value, the new satisfies keyword will allow TypeScript to infer it automatically."
By using satisfies GetProducts<void>, you're telling TypeScript to check that the function conforms to the GetProducts type, while still allowing it to infer the specific return type based on your Prisma query.
This method is particularly useful when dealing with complex return types or when you frequently change the shape of your query results. It provides a good balance between type safety and development flexibility.
Remember, this approach requires TypeScript 4.9 or later, which supports the satisfies keyword. Make sure your project is using a compatible TypeScript version to take advantage of this feature.
Wasp Documentation on Queries provides more information on implementing queries in Wasp, although it doesn't specifically mention the satisfies keyword (as of my last update). This approach you've shown is a more advanced TypeScript feature that can be very useful in Wasp projects.
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Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
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Sorry @miho, I seem to be having a bit of trouble. Don't worry though, I've pinged my support and they will try to fix me up! :technologist:
Perhaps try again in 15mins?