In the type definition below, is there a way to require name or model, instead of name and model?
type Starship {
id: ID!
name: String!
model: String!
length(unit: LengthUnit = METER): Float
}
I may have name or model due to some legacy data limitations. I would rather enforce this at the GraphQL validation layer, rather than in code.
EDIT:
There is some good discussion about adding validation to the graphQL spec, which you can read here: https://github.com/graphql/graphql-js/issues/361
There are also a couple of libraries to extend validation:
https://github.com/xpepermint/graphql-type-factory
https://github.com/stephenhandley/graphql-validated-types
I'm going to stick with validating the types in code, at least until they add better support.
You could try to use union to represent name or model concept . As union only works with object type now , that means you have also model name and model as object type first.
Code wise the schema looks like :
type Name {
value : String!
}
type Model {
value : String!
}
union NameOrModel = Name | Model
type Starship {
id: ID!
nameOrModel : NameOrModel!
length(unit: LengthUnit = METER): Float
}
It is very ugly IMO as it introduces many unnecessary noise and complexity to the schema .So I would prefer to stick with your original schema and do that check manually in the backend.
From the spec:
By default, all types in GraphQL are nullable; the null value is a valid response for all of the above types. To declare a type that disallows null, the GraphQL Non‐Null type can be used. This type wraps an underlying type, and this type acts identically to that wrapped type, with the exception that null is not a valid response for the wrapping type. A trailing exclamation mark is used to denote a field that uses a Non‐Null type like this: name: String!.
An individual field may be nullable or non-nullable. Non-null validation happens at the field level, independent of other fields. So there is no mechanism for validating whether some combination of fields are or are not null.
Related
I have a type that needs to be like the following
type ActivityPayload {
action: String!
extra: AnythingAtAll
}
Where AnythingAtAll is an arbitrary JSON format. So that's as far as I get because all the tutorials I see expect you to have a type AnythingAtAll with fields defined inside of it. How do I allow {}, or {any properties in json format no matter what the property names and values are}
Use graphql-scalars:
A library of custom GraphQL scalar types for creating precise type-safe GraphQL schemas.
This library offers also the scalar type JSON:
The JSON scalar type represents JSON values as specified by ECMA-404.
Then you can do the following:
type ActivityPayload {
action: String!
extra: JSON
}
See also graphql-type-json (JSON is based on this one).
what's the difference between schema and documents in Graphql?
schema is like this:
type Query {
fo: String
}
but the document is like:
query SomeQuery {
foo {
bar
}
}
the spec is really confusing https://graphql.github.io/graphql-spec/June2018/#sec-Language.Document
I always use schema but for client-side type generation in graphql-code-generator it needs document file. https://graphql-code-generator.com/docs/getting-started/documents-field
A document is really any string containing valid GraphQL syntax. According to the spec, a document contains one or more definitions, where a definition could be:
an operation definition
query UsersQuery {
users {
id
email
}
}
a fragment definition
fragment UserFragment on User {
id
email
}
a type system definition
type User {
id: ID!
email: String!
}
a type system extension
extend type User {
name: String
}
Operation and fragment definitions are known as executable definitions. Documents sent to a GraphQL service must only contain executable definitions. Type system definitions and extensions are used in describing a schema -- that's why we commonly call them Schema Definition Language (SDL). A schema is a GraphQL service's "collective type system capabilities" -- it's basically a collection of types and directives that represent everything your GraphQL service can do.
A schema may be described using type system definitions, but it's not really accurate to say that the type definitions are the schema because the schema itself also includes the actual field resolution logic as well.
I'm a newbie to Prisma/GraphQL. I'm writing a simple ToDo app and using Apollo Server 2 and Prisma GraphQL for the backend. I want to convert my createdAt field from the data model to something more usable on the front-end, like a UTC date string. My thought was to convert the stored value, which is a DateTime.
My datamodel.prisma has the following for the ToDo type
type ToDo {
id: ID! #id
added: DateTime! #createdAt
body: String!
title: String
user: User!
completed: Boolean! #default(value: false)
}
The added field is a DataTime. But in my schema.js I am listing that field as a String
type ToDo {
id: ID!
title: String,
added: String!
body: String!
user: User!
completed: Boolean!
}
and I convert it in my resolver
ToDo: {
added: async (parent, args) => {
const d = new Date(parent.added)
return d.toUTCString()
}
Is this OK to do? That is, have different types for the same field in the datamodel and the schema? It seems to work OK, but I didn't know if I was opening myself up to trouble down the road, following this technique in other circumstances.
If so, the one thing I was curious about is why accessing parent.added in the ToDo.added resolver doesn't start some kind of 'infinite loop' -- that is, that when you access the parent.added field it doesn't look to the resolver to resolve that field, which accesses the parent.added field, and so on. (I guess it's just clever enough not to do that?)
I've only got limited experience with Prisma, but I understand you can view it as an extra back-end GraphQL layer interfacing between your own GraphQL server and your data (i.e. the database).
Your first model (datamodel.prisma) uses enhanced Prisma syntax and directives to accurately describe your data, and is used by the Prisma layer, while the second model uses standard GraphQL syntax to implement the same object as a valid, standard GraphQL type, and is used by your own back-end.
In effect, if you looked into it, you'd see the DateTime type used by Prisma is actually a String, but is likely used by Prisma to validate date & time formats, etc., so there is no fundamental discrepancy between both models. But even if there was a discrepancy, that would be up to you as you could use resolvers to override the data you get from Prisma before returning it from your own back-end.
In short, what I'm trying to say here is that you're dealing with 2 different GraphQL layers: Prisma and your own. And while Prisma's role is to accurately represent your data as it exists in the database and to provide you with a wide collection of CRUD methods to work with that data, your own layer can (and should) be tailored to your specific needs.
As for your resolver question, parent in this context will hold the object returned by the parent resolver. Imagine you have a getTodo query at the root Query level returning a single item of type ToDo. Let's assume you resolve this to Prisma's default action to retrieve a single ToDo. According to your datamodel.prisma file, this query will resolve into an object that has an added property (which will exist in your DB as the createdAt field, as specified by the #createdAt Prisma directive). So parent.added will hold that value.
What your added resolver does is transform that original piece of data by turning it into an actual Date object and then formatting it into a UTC string, which conforms to your schema.js file where the added field is of type String!.
I have an input type in my schema that specifies lots of attributes, as it's intended to do. The issue is that what I'm sending to the mutation that will persist these objects is an object with arbitrary fields that may change. As it stands, if I send attributes not specified in the schema, I get the error:
Validation error of type WrongType: argument 'input' with value (...)
contains a field not in 'BotInput': 'ext_gps' # 'setBot'
Concretely, my input type did not specify the attribute exp_gps, and that field was provided.
My Question
Is there a way to make it so the input validation simply ignores any attributes not in the schema, so that it continues to perform the mutation with only whatever was specified in the schema? It'll be often that I don't want to persist the additional attributes, so dropping them is fine, as long as the other attributes get added.
GraphQL does not support arbitrary fields, there is a RFC to support a Map type but it has not been merged/approved into the specification.
I see two possible workarounds that both require to change your schema a little bit.
Say you have the following schema:
type Mutation {
saveBot(input: BotInput) : Boolean
}
input BotInput {
id: ID!
title: String
}
and the input object is:
{
"id": "123",
"title": "GoogleBot",
"unrelated": "field",
"ext_gps": "else"
}
Option 1: Pass the arbitrary fields as AWSJSON
You would change your schema to:
type Mutation {
saveBot(input: BotInput) : Boolean
}
input BotInput {
id: ID!
title: String
arbitraryFields: AWSJSON // this will contain all the arbitrary fields in a json string, provided your clients can pluck them from the original object, make a map out of them and json serialize it.
}
So the input in our example would be now:
{
"id": "123",
"title": "GoogleBot",
"arbitraryFields": "{\"unrelated\": \"field\", \"ext_gps\": \"else\"}"
}
In your resolver, you could take the arbitraryFields string, deserialize it, and hydrate the values on the BotInput object before passing it to the data source.
Option 2: Pass the input as AWSJSON
The principle is the same but you pass the entire BotInput as AWSJSON.
type Mutation {
saveBot(input: AWSJSON) : Boolean
}
You don't have to do the resolver hydration and you don't have to change your client, but you lose the GraphQL type validation as the whole BotInput is now a blob.
I've recently started to research the possibility of using GraphQL for requesting dynamic data configurations. The very first thing that jumps out at me is the strongly-typed concept of GraphQL.
Is there a way for GraphQL schemas to handle arrays of mixed type objects? I would greatly appreciate either an explanation or possibly a reference I can read over.
I am currently working with GraphQL with Node.js but a later implementation will be out of a Java Container. All data will be JSON pulled from MongoDB.
You either have to make these disparate types implement the same interface, make your resolvers return unions, or create a custom scalar to hold the dynamic data.
The cleanest approach is the first one: if your resulting objects can be of a limited number of types, define the types so that they implement the same interface, and type your resolvers by the interface. This allows the client to conditionally select sub-fields based on the actual type, and you maintain type safety.
The second approach has similar limitations: you need to know the possible types ahead of time, but they do not have to implement the same interface. It is preferable when the possible values are unrelated to each other and have either/or semantics, like success/failure.
The custom scalar approach is the only one in which you do not need to know the possible types of the result, i.e. the structure of the result can be completely dynamic. Here's an implementation of that approach, known as JSON scalar (i.e. cram any JSON-serializable structure into a scalar value). The big downside of this approach is that it makes sub-selection impossible, as the entire value becomes one big scalar (even though it's a complex object).
Since the question is asking about an array of objects of unknown types, I'll point out that you can, of course, have a list of all the options above.
Examples:
#Interface for any search result
interface SearchResult {
title: String!
url: String!
}
#A specific kind of search result
type Book implements SearchResult {
title: String!
url: String!
author: Author!
isbn: String!
}
type Article implements SearchResult {
title: String!
url: String!
categories: [Category]!
}
type Query {
#Search can return a mix of Books and Articles
search(keyword: String!): [SearchResult!]
}
Or
#No interface this time
type Book {
name: String! #No common fields with Article
author: Author!
publisher: Publisher!
}
type Article {
title: String!
url: String!
categories: [Category]!
}
union SearchResult = Book | Article
type Query {
#Search can return a mix of Books and Articles
search(keyword: String!): [SearchResult!]
}
Or
scalar JSON
type Query {
#Search can return anything at all... All bets are off
search(keyword: String!): [JSON!]
}
If data is completely JSON and you would rather preserve them as is, check out JSON scalar type. Basically,
import { GraphQLObjectType } from 'graphql';
import GraphQLJSON from 'graphql-type-json';
export default new GraphQLObjectType({
name: 'MyType',
fields: {
myField: { type: GraphQLJSON },
},
});
I think it's possible to make a custom/generic type that will fit the need.
So that way it's still a strong typed array but the type will be flexable enough to set what you need.
Here is an example with custom types:
https://github.com/stylesuxx/graphql-custom-types