GraphQL 解析器,用于按名称而不是 ID 获取项目
Posted
技术标签:
【中文标题】GraphQL 解析器,用于按名称而不是 ID 获取项目【英文标题】:GraphQL Resolver for getting item by name, not ID 【发布时间】:2019-08-21 11:42:38 【问题描述】:我有一个带有成分的 DynamoDB。 AWS Appsync 为我创建了一个解析器,因此我可以通过 ID 获取成分,但我需要能够通过名称获取成分。我已经尝试为此编写一个解析器,但它不起作用。
最终我需要编写一个解析器或 API,它接受一个字符串列表并返回与这些字符串匹配的成分(如果它们存在),但这是第一步,我希望如果我能做到这一点,我可以创建它的批处理版本。
解析器:
"version": "2017-02-28",
"operation": "GetItem",
"key":
"name": $util.dynamodb.toDynamoDBJson($util.transform.toDynamoDBFilterExpression($ctx.args.filter))
响应映射模板
$util.toJson($ctx.result)
架构:
input CreateIngredientInput
name: String!
vegan: Vegan
gf: GlutenFree
input DeleteIngredientInput
id: ID!
enum GlutenFree
GLUTENFREE
CONTAINSGLUTEN
UNKNOWN
type Ingredient
id: ID!
name: String!
vegan: Vegan
gf: GlutenFree
type IngredientConnection
items: [Ingredient]
nextToken: String
input ModelBooleanFilterInput
ne: Boolean
eq: Boolean
input ModelFloatFilterInput
ne: Float
eq: Float
le: Float
lt: Float
ge: Float
gt: Float
contains: Float
notContains: Float
between: [Float]
input ModelIDFilterInput
ne: ID
eq: ID
le: ID
lt: ID
ge: ID
gt: ID
contains: ID
notContains: ID
between: [ID]
beginsWith: ID
input ModelIntFilterInput
ne: Int
eq: Int
le: Int
lt: Int
ge: Int
gt: Int
contains: Int
notContains: Int
between: [Int]
enum ModelSortDirection
ASC
DESC
input ModelStringFilterInput
ne: String
eq: String
le: String
lt: String
ge: String
gt: String
contains: String
notContains: String
between: [String]
beginsWith: String
type Mutation
createIngredient(input: CreateIngredientInput!): Ingredient
updateIngredient(input: UpdateIngredientInput!): Ingredient
deleteIngredient(input: DeleteIngredientInput!): Ingredient
type Query
getIngredient(id: ID!): Ingredient
getIngredientByName(name: String!): Ingredient
listIngredients(filter: TableIngredientFilterInput, limit: Int, nextToken: String): IngredientConnection
type Subscription
onCreateIngredient(
id: ID,
name: String,
vegan: Vegan,
gf: GlutenFree
): Ingredient
@aws_subscribe(mutations: ["createIngredient"])
onUpdateIngredient(
id: ID,
name: String,
vegan: Vegan,
gf: GlutenFree
): Ingredient
@aws_subscribe(mutations: ["updateIngredient"])
onDeleteIngredient(
id: ID,
name: String,
vegan: Vegan,
gf: GlutenFree
): Ingredient
@aws_subscribe(mutations: ["deleteIngredient"])
input TableBooleanFilterInput
ne: Boolean
eq: Boolean
input TableFloatFilterInput
ne: Float
eq: Float
le: Float
lt: Float
ge: Float
gt: Float
contains: Float
notContains: Float
between: [Float]
input TableIDFilterInput
ne: ID
eq: ID
le: ID
lt: ID
ge: ID
gt: ID
contains: ID
notContains: ID
between: [ID]
beginsWith: ID
input TableIngredientFilterInput
id: TableIDFilterInput
name: TableStringFilterInput
vegan: TableBooleanFilterInput
gf: TableBooleanFilterInput
input TableIntFilterInput
ne: Int
eq: Int
le: Int
lt: Int
ge: Int
gt: Int
contains: Int
notContains: Int
between: [Int]
input TableStringFilterInput
ne: String
eq: String
le: String
lt: String
ge: String
gt: String
contains: String
notContains: String
between: [String]
beginsWith: String
input UpdateIngredientInput
id: ID!
name: String
vegan: Vegan
gf: GlutenFree
enum Vegan
VEGAN
NONVEGAN
UNKNOWN
当我运行这个查询时:
query getIt
getIngredientByName(name: "demerara")
id
name
vegan
gf
我得到了回应:
"data":
"getIngredientByName": null
,
"errors": [
"path": [
"getIngredientByName"
],
"data": null,
"errorType": "DynamoDB:AmazonDynamoDBException",
"errorInfo": null,
"locations": [
"line": 2,
"column": 3,
"sourceName": null
],
"message": "The provided key element does not match the schema (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID: 58EKL6IO63VL44Q1DTG9JFNJB7VV4KQNSO5AEMVJF66Q9ASUAAJG)"
]
虽然 demerara 绝对是我数据库中的一种成分。
【问题讨论】:
你能分享你表上的键模式吗?从错误消息看来,这似乎就是它正在苦苦挣扎的地方。 不确定关键架构是什么,我的架构在上面 DynamoDB 表的关键结构。 【参考方案1】:我知道这很旧,但我最近遇到了一个类似的问题,我可以通过向我想要搜索的架构属性添加 @key
指令来解决:
type User @model @key(name: "getUserByCognitoId", fields: ["cognitoId"], queryField: "getUserByCognitoId")
id: ID!
cognitoId: ID!
...
文档:https://docs.amplify.aws/cli/graphql-transformer/directives#key
这样 AppSync 会为您生成解析器并添加排序键,以提高查询 DynamoDB 的效率
【讨论】:
【参考方案2】:我想出了一个办法,虽然有点作弊。
当我在 AppSync 架构中创建资源时,有一个“附加索引”下拉菜单,如果我按 ID 创建初始索引,然后是第二个索引“名称”,它将创建一个带有解析器的查询你。就我而言
queryIngredientsByNameIndex(name: String!, first: Int, after: String): IngredientConnection
查询,解析器为
"version": "2017-02-28",
"operation": "Query",
"query":
"expression": "#name = :name",
"expressionNames":
"#name": "name",
,
"expressionValues":
":name": $util.dynamodb.toDynamoDBJson($ctx.args.name),
,
,
"index": "name-index",
"limit": $util.defaultIfNull($ctx.args.first, 20),
"nextToken": $util.toJson($util.defaultIfNullOrEmpty($ctx.args.after, null)),
"scanIndexForward": true,
"select": "ALL_ATTRIBUTES",
【讨论】:
以上是关于GraphQL 解析器,用于按名称而不是 ID 获取项目的主要内容,如果未能解决你的问题,请参考以下文章
如何在 GraphQL 解析器中添加用于缓存的 redis 客户端