在 AWS AppSync 中对 SQL 查询的 JSON 对象进行字符串化

Question：如何在 Appsync 速度模板中对 SQL 语句的 JSON 对象进行字符串化？

解释：我有一个 Aurora RDS 表，其中有一列数据类型为 JSON。 AppSync API 已连接到 RDS。 我的 GraphQL 模式看起来像

input CreateServiceCatalogItemInput {
    serviceName: String!
    serviceConfig: ServiceConfigInput!
}

type Mutation {
    createServiceCatalogItem(input: CreateServiceCatalogItemInput!): ServiceCatalogItem
}

type Query {
    getAllServiceCatalogItem: [ServiceCatalogItem]
}

type ServiceCatalogItem {
    serviceId: ID!
    serviceName: String!
    serviceConfig: ServiceConfig!
}

type ServiceConfig {
    connectionType: String
    capacity: Int
}

input ServiceConfigInput {
    connectionType: String
    capacity: Int
}

schema {
    query: Query
    mutation: Mutation
}

我的 createServiceCatalogItem 突变解析器看起来像

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '$util.toString($ctx.args.input.serviceConfig)') RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}

这引发了我的错误：

在 com.amazonaws.deepdish.transform.util.TransformUtils 类中调用方法“toString”引发异常 java.lang.IllegalArgumentException：参数数量错误...

If I do:

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '$util.toJson($ctx.args.input.serviceConfig)') RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}

这引发了我的错误：

无法解析 JSON 文档：'意外字符（'c'（代码 99））：需要逗号分隔数组条目\n at ...

If I do:

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '$ctx.args.input.serviceConfig') RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}

然后我得到了有道理的错误：

RDSHttp:{"message":"错误：json 类型的输入语法无效\n 详细信息：令牌 \"connectionType\" 无效。\n 位置：222\n 其中：JSON 数据，第 1 行：{connectionType..." }

但是，当我在解析器中对 JSON 进行硬编码时，它会起作用：

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '{\"connectionType\":\"ftth\",\"capacity\":1}') RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}

那么如何将 {connectionType=ftth,capacity=1} 转换为 {"connectionType":"ftth", "capacity":1} ？我做错了什么或者我错过了什么？任何帮助将不胜感激。

您可以像这样构建一个 JSON 变量：

#set($json = $util.toJson({
  "connectionType": "$ctx.args.input.serviceConfig.connectionType",
  "capacity": $ctx.args.input.serviceConfig.capacity
  }))

并在您的查询中插入：

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '$util.escapeJavaScript($json)' RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}

由于所有的引号和转义，上面有点具有挑战性，但我认为使用escapeJavaScript会成功的。

或者直接：

{
    "version": "2018-05-29",
    "statements": [
        "INSERT INTO b2b_service_catalog(service_name, service_config) VALUES ('$ctx.args.input.serviceName', '{\"connectionType\":\"$ctx.args.input.serviceConfig.connectionType\",\"capacity\": $ctx.args.input.serviceConfig.capacity}') RETURNING service_id AS \"serviceId\", service_name AS \"serviceName\", service_config AS \"serviceConfig\"",
    ]
}