我一直试图定义我认为是非常基本的突变。 我是所有Scala,GraphQL,Akka HTTP的新手,而不是母语人士,所以请原谅我,如果下面的任何内容都是废话!对于冗长的帖子感到抱歉,我确实尝试用最少的例子来保持简短,但我觉得完整的背景很重要。
我有以下代码定义Transaction
案例类,所有事务的假数据库,以及查询和创建事务的模式:
case class Transaction(id: Int, description: String, amount: BigDecimal)
object TransactionDB {
var transactions: List[Transaction] = Nil
}
class TransactionDB {
def transaction(id: Int): Option[Transaction] =
TransactionDB.transactions.find(_.id == id)
def createTransaction(transaction: Transaction) = {
TransactionDB.transactions = transaction :: TransactionDB.transactions
transaction
}
}
import sangria.macros.derive._
import sangria.marshalling.sprayJson._
import sangria.schema._
import spray.json._
import DefaultJsonProtocol._
object TransactionSchema {
val Id = Argument("id", IntType)
val TransactionType = deriveObjectType[Unit, Transaction]()
val QueryType = ObjectType("Query", fields[TransactionDB, Unit](
Field("transaction", OptionType(TransactionType),
arguments = Id :: Nil,
resolve = c ⇒ c.ctx.transaction(c.arg(Id))
)
))
implicit val transactionFormat = jsonFormat3(Transaction)
val TransactionInputType = deriveInputObjectType[Transaction](
InputObjectTypeName("TransactionInput")
)
val TransactionArg = Argument("transaction", TransactionInputType)
val MutationType = ObjectType("Mutation", fields[TransactionDB, Unit](
Field("createTransaction", TransactionType,
arguments = TransactionArg :: Nil,
resolve = c ⇒ c.ctx.createTransaction(c.arg(TransactionArg))
)
))
val schema = Schema(QueryType, Some(MutationType))
}
生成的GraphQL架构如下:
type Mutation {
createTransaction(transaction: TransactionInput!): Transaction!
}
type Query {
transaction(id: Int!): Transaction
}
type Transaction {
id: Int!
description: String!
amount: BigDecimal!
}
input TransactionInput {
id: Int!
description: String!
amount: BigDecimal!
}
然后我可以创建一个事务并使用以下查询进行查询:
mutation {
createTransaction(transaction: {
id: 1
description: "Electricity bill"
amount: 100
}) {
id
}
}
query {
transaction(id: 1) {
id
description
amount
}
}
但是,id
不应该是突变的一部分。理想情况下,我得到:
input TransactionInput {
description: String!
amount: BigDecimal!
}
type Mutation {
createTransaction(input: TransactionInput): Transaction
updateTransaction(id: Int!, input: TransactionInput): Transaction # For later
}
在itertools.product
中,这是使用以下内容完成的:
createTransaction({description, amount}) {
const id = generateId();
transactionRepo[id] = new Transaction(id, description, amount);
return transaction[id];
},
updateTransaction(id, {description, amount}) { // Assuming id exists
transactionRepo[id] = new Transaction(id, description, amount);
return transactionRepo[id];
},
在Scala / Sangria中寻找解决方案是我陷入困境的地方。
尝试1:我在考虑这样的事情:
def createTransaction(description: String, amount: BigDecimal) = {
val r = scala.util.Random // Or leave this to the DB layer
val transaction = Transaction(r.nextInt(10000), description, amount)
TransactionDB.transactions = transaction :: TransactionDB.transactions
transaction
}
但是这不起作用,因为createTransaction
被TransactionArg
映射到Transaction
。
尝试2 :由于删除jsonFormat2
,我还尝试切换到id
,但这会在编译时触发type mismatch
因为{{1}有3个属性。
尝试3 :我尝试使用以下内容更新派生的Transaction
以排除InputObjectType
:
id
这会编译,但在尝试运行上面给出的突变结果时:
val TransactionInputType = deriveInputObjectType[Transaction](
InputObjectTypeName("TransactionInput"),
ExcludeInputFields("id")
)
字段中省略Argument 'transaction' has invalid value: Object is missing required member 'id'
时id
。createTransaction(transaction: {...})
。我错过了什么?使用Argument 'transaction' expected type 'TransactionInput!' but got: {id: 42, description: \"Electricity bill\", amount: 100}. Reason: Unknown field 'id' is not defined in the input type 'TransactionInput'.
对我来说似乎很简单,但我无法使用Sangria在Scala中找到如何做到这一点。我多次阅读文档并广泛关注Google,因为这似乎是一个简单的问题,但没有找到类似的东西。谢谢!
答案 0 :(得分:4)
似乎createTransaction
和updateTransaction
都返回了Transaction
类型定义为:
type Transaction {
id: Int!
description: String!
amount: BigDecimal!
}
id: Int!
表示需要id
(这是!
的含义)所以我首先将其重新定义为:id: Int
(无感叹号)。