Imagine the following (simplified) GraphQL schema:
type User {
username: String
email: String
}
type Query {
user(username: String, email: String): User
}
If I would only want to allow querying user by giving a username, I would of course change it to user(username: String!), making the username required using the exclamation mark. Same thing vice versa with the email.
Is it possible though to have a GraphQL native solution where I validate for the existence of only either one (logical XOR) or at least one (logical OR) of the two input parameters?
Of course I could do it in the query resolver manually, but a #constraint directive like it is being used in Apollo GraphQL spreading across variables would be nice.
Directly ... not possible:
check fields existence [within args] on resolver;
use #constraint to check each field shape;
Indirectly:
you can try to use union of input types:
.
type UserNameInput {
username: String!
}
type UserEmailInput {
email: String!
}
type UserInput = UserNameInput | UserEmailInput
type Query {
user(input: UserInput): User
}
Related
I have some problems when using Fauna and GraphQL
When I use GraphQL to update data, all parameters are required
For example
// Schema
type User {
username: String!
password: String!
phone: String!
}
// Mutation
mutation {
updateUser(id: "xxxxx", {"phone": "+886 110220330"}){
username,
phone
}
}
// Error
But I only want to update the phone data this time, how can I skip other parameters?
Although it can solve the problem when I delete the Not null of all attributes in User type,
But it doesn't look like a good way and safe
// after
// Schema
type User {
username: String
password: String
phone: String
}
There is a preview feature that you can use by adding a header to your GraphQL query.
X-Schema-Preview: partial-update-mutation
Once you do this, you will have access to a new mutation called partialUpdateUser which will make all of the input values optional.
See the docs for more information: https://docs.fauna.com/fauna/current/api/graphql/previews/
I have a schema like so:
scalar Date
schema {
query: Query
}
type Query {
user(id: ID!): User
messages(userId: ID!): [ChatMessage!]!
}
type User {
id: ID!
username: String!
email: String!
}
type ChatMessage {
id: ID!
content: String!
time: Date!
user: User!
}
And I want to make an operation where you can get all messages for a user, but since User and ChatMessage are in separate database tables I would need to perform two queries (one to get the ChatMessages and one to get the User), so I thought I should model it like so:
query findMessagesForUser($userId: ID!) {
messages(userId: $userId) {
id
content
user(id: $userId) {
username
email
}
}
}
This returns a parse error on the schema:
GraphQLDocumentError: Unknown argument "id" on field "ChatMessage.user".
So, how do I get the $userId argument passed to the resolver for ChatMessage.user?
In your schema, you’ve defined an id input on your Query.user method. In your query, you are trying to supply an id to the Message.user property, however you haven't defined this input in your schema.
If you wanted to accept an id on ChatMessage.user, you'd need to define it as:
type ChatMessage {
id: ID!
content: String!
time: Date!
user(id: ID!): User
}
However, it wouldn't really make sense (at least to me) to construct a schema this way, I assume there's only one user (author) per message.
As indicated by #xadm, the object you resolved at the ChatMessage level will be passed into the user resolver as the first argument.
Even if you're not exposing ChatMessage.userId in the schema (that's fine), you'd still probably load this up in your back- end (the foreign key value in the ChatMessage table) and set this on the object used to resolve ChatMessage.
This way, you'll (lazy) load user IF that's included in the query, using the userId property of the parent ChatMessage object argument (remember you don't need to expose ChatMessage.userId via the schema, it's just on the object you use to resolve ChatMessage).
I'd consider modelling more like this (filter input used as an additional contrived example):
type Query {
user(id: ID!): User
messages(filter: MessageFilter): [ChatMessage!]!
}
type MessageFilter {
search: String
paging: PagingFilter
}
type PagingFilter {
after: ID!
pageSize: Int!
}
type User {
id: ID!
username: String!
email: String!
messages(filter: MessageFilter): [ChatMessage!]!
}
In your resolver map, you can wire up the same function to resolve messages at the User level and at the Query level. The only difference is you wouldn't have a userId at the Query level.
If consumers want to view/search messages from all users, they use the top level Query messages method.
{
messages({search: 'graphql'}) {
id,
content,
time
}
}
If the consumer wants to view/search one user's messages, go through the top level Query users method into messages.
{
user(id: 3) {
messages({search: 'graphql'}) {
id,
content,
time
}
}
}
The filter example is contrived, but could provide basic paging for loading of messages.
apollographql.com/docs/graphql-tools/resolvers
I want to bulk update list of entries with graphQL mutation in faunaDB.
The input data is list of coronavirus cases from external source. It will be updated frequently. The mutation should update existing entries if the entry name is present in collectio and create new ones if not present.
Current GRAPHQL MUTATION
mutation UpdateList($data: ListInput!) {
updateList(id: "260351229231628818", data: $data) {
title
cities {
data {
name
infected
}
}
}
}
GRAPHQL VARIABLES
{
"data": {
"title": "COVID-19",
"cities": {
"create": [
{
"id": 22,
"name": "Warsaw",
"location": {
"create": {
"lat": 52.229832,
"lng": 21.011689
}
},
"deaths": 0,
"cured": 0,
"infected": 37,
"type": "ACTIVE",
"created_timestamp": 1583671445,
"last_modified_timestamp": 1584389018
}
]
}
}
}
SCHEMA
type cityEntry {
id: Int!
name: String!
deaths: Int!
cured: Int!
infected: Int!
type: String!
created_timestamp: Int!
last_modified_timestamp: Int!
location: LatLng!
list: List
}
type LatLng {
lat: Float!
lng: Float!
}
type List {
title: String!
cities: [cityEntry] #relation
}
type Query {
items: [cityEntry!]
allCities: [cityEntry!]
cityEntriesByDeathFlag(deaths: Int!): [cityEntry!]
cityEntriesByCuredFlag(cured: Int!): [cityEntry!]
allLists: [List!]
}
Everytime the mutation runs it creates new duplicates.
What is the best way to update the list within single mutation?
my apologies for the delay, I wasn't sure exactly what the missing information was hence why I commented first :).
The Schema
An example of a part of a schema that has arguments:
type Mutation {
register(email: String!, password: String!): Account! #resolver
login(email: String!, password: String!): String! #resolver
}
When such a schema is imported in FaunaDB there will be placeholder functions provided.
The UDF parameters
As you can see all the function does is Abort with the message that the function still has to be implemented. The implementation starts with a Lambda that takes arguments and those arguments have to match what you defined in the resolver.
Query(Lambda(['email', 'password'],
... function body ...
))
Using the arguments is done with Var, that means Var('email') or Var('password') in this case. For example, in my specific case we would use the email that was passed in to get an account by email and use the password to pass on to the Login function which will return a secret (the reason I do the select here is that the return value for a GraphQL resolver has to be a valid GraphQL result (e.g. plain JSON
Query(Lambda(['email', 'password'],
Select(
['secret'],
Login(Match(Index('accountsByEmail'), Var('email')), {
password: Var('password')
})
)
))
Calling the UDF resolver via GraphQL
Finally, how to pass parameters when calling it? That should be clear from the GraphQL playground as it will provide you with the docs and autocompletion. For example, this is what the auto-generated GraphQL docs tell me after my schema import:
Which means we can call it as follows:
mutation CallLogin {
login (
email: "<some email>"
password: "<some pword>"
)
}
Bulk updates
For bulk updates, you can also pass a list of values to the User Defined Function (UDF). Let's say we would want to group a number of accounts together in a specific team via the UI and therefore want to update multiple accounts at the same time.
The mutation in our Schema could look as follows (ID's in GraphQL are similar to Strings)
type Mutation { updateAccounts(accountRefs: [ID]): [ID]! #resolver }
We could then call the mutation by providing in the id's that we receive from FaunaDB (the string, not the Ref in case you are mixing FQL and GraphQL, if you only use GraphQL, don't worry about it).
mutation {
updateAccounts(accountRefs: ["265317328423485952", "265317336075993600"] )
}
Just like before, we will have to fill in the User Defined Function that was generated by FaunaDB. A skeleton function that just takes in the array and returns it would look like:
Query(Lambda(['arr'],
Var('arr')
))
Some people might have seen an easier syntax and would be tempted to use this:
Query(Lambda(arr => arr))
However, this currently does not work with GraphQL when passing in arrays, it's a known issue that will be fixed.
The next step is to actually loop over the array. FQL is not declarative and draws inspiration from functional languages which means you would do that just by using a 'map' or a 'foreach'
Query(Lambda(["accountArray"],
Map(Var("accountArray"),
Lambda("account", Var("account")))
))
We now loop over the list but don't do anything with it yet since we just return the account in the map's body. We will now update the account and just set a value 'teamName' on there. For that we need the Update function which takes a FaunaDB Reference. GraphQL sends us strings and not references so we need to transform these ID strings to a reference with Ref as follows:
Ref(Collection('Account'), Var("account"))
If we put it all together we can add an extra attribute to a list of accounts ids as follows:
Query(Lambda(["accountArray"],
Map(Var("accountArray"),
Lambda("account",
Do(
Update(
Ref(Collection('Account'), Var("account")),
{ data: { teamName: "Awesome live-coders" } }
),
Var("account")
)
)
)
))
At the end of the Map, we just return the ID of the account again with Var("account") in order to return something that is just plain JSON, else we would be returning FaunaDB Refs which are more than just JSON and will not be accepted by the GraphQL call.
Passing in more complex types.
Sometimes you want to pass in more complex types. Let's say we have a simple todo schema.
type Todo {
title: String!
completed: Boolean!
}
And we want to set the completed value of a list of todos with specific titles to true. We can see in the extended schema generated by FaunaDB that there is a TodoInput.
If you see that extended schema you might think, "Hey that's exactly what I need!" but you can't access it when you write your mutations since you do not have that part of the schema at creation time and therefore can't just write:
type Mutation { updateTodos(todos: [TodoInput]): Boolean! #resolver }
As it will return the following error.
However, we can just add it to the schema ourselves. Fauna will just accept that you already wrote it and not override it (make sure that you keep the required fields, else your generated 'createTodo' mutation won't work anymore).
type Todo {
title: String!
completed: Boolean!
}
input TodoInput {
title: String!
completed: Boolean!
}
type Mutation { updateTodos(todos: [TodoInput]): Boolean! #resolver }
Which means that I can now write:
mutation {
updateTodos(todos: [{title: "test", completed: true}])
}
and dive into the FQL function to do things with this input.
Or if you want to include the ID along with data you can define a new type.
input TodoUpdateInput {
id: ID!
title: String!
completed: Boolean!
}
type Mutation { updateTodos(todos: [TodoUpdateInput]): Boolean! #resolver }
Once you get the hang of it and want to learn more about FQL (that's a whole different topic) we are currently writing a series of articles along with code for which the first one appeared here: https://css-tricks.com/rethinking-twitter-as-a-serverless-app/ which is probably a good gentle introduction.
I am trying to create a GraphQL Schema such that a user will be able to find a user by their email or username. Imagine for these purposes one user could have an email that is the username of another user.
My typeDefs look as follows:
const typeDefs = gql`
type Query {
user: User(username: String!)
user: User(email: String!)
}
`;
Is this a valid Schema? If not how would I change my solution to be valid and solve my problem?
Edit: So I tried to execute the above and I get an error: 'Error: Field "Query.user" can only be defined once.' As I thought I might.
Is there any way to ensure that exactly one of username and email is null in the following: user: User(username: String, email: String)?
There is no "overloading" of fields in GraphQL, and no syntax that would support one of two fields being required. An argument is either nullable or non-null, that's it. You can do this:
type Query {
user(username: String, email: String): User
}
or this
type Query {
user(filter: UserFilter!): User
}
input UserFilter {
username: String
email: String
}
and then handle validation (at least one argument is defined but not both) inside your resolver. The only other way to do it would be something like:
type Query {
user(key: UserFilterKey!, value: String!): User
}
enum UserFilterKey {
username
email
}
But this kind of approach is not very intuitive for anyone consuming the schema. It also only works if the arguments in question have the same type.
I try to use fragments in GraphQL
There is my schema
user/getUser.gql
input GetUserByUsernameInput {
username: String!
}
fragment UserFragment on User {
username
information
pictureUrl
}
type UserType {
...UserFragment
}
type GetUserByUsernameResponse {
user: UserType
errors: [Error]!
}
type Query {
getUserByUsername(input: GetUserByUsernameInput!): GetUserByUsernameResponse!
}
shared/User.gql
type User {
id: Int!
username: String!
email: String!
information: String
pictureUrl: String
}
And I got dummy error
(node:26206) UnhandledPromiseRejectionWarning: Syntax Error: Expected Name, found ...
GraphQL request (12:9)
11: type UserType {
12: user: ...UserFragment
^
13: }
How should my code looks like to use GraphQL fragments?
PS. I use graphql-code-generator
Fragments only exist in queries; you can't use them in the schema language.
In your example the response should include a reference to the User that's being returned:
type GetUserByUsernameResponse {
user: User
errors: [Error]!
}
When you make a query, though, you can include the fragment.
query WhoAreYou($username: String!) {
getUserByUsername(input: {username: $username}) {
user { ...UserFragment }
errors { message }
}
}
fragment UserFragment on User {
username
information
pictureUrl
}
Fragments tend to be somewhat more useful if either you have reason to request the same fields on the same type of object multiple times in one query, or if you have a client library that's capable of picking fragments out of a "library" of GraphQL queries you'll use multiple places. (For example, the Ruby graphql-client gem can be configured with a file of many queries, and you can make a specific query out of it by operation name and it will make a query with that operation and any fragments it references, so you can reuse the same fragments across several queries.)