Graphql 在AWS AppSync中为SQL查询字符串化JSON对象

问题：如何在Appsync velocity模板中为SQL语句字符串化JSON对象

解释：我有一个Aurora RDS表，它有一个数据类型为JSON的列。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
}

{
    "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\"",
    ]
}

createServiceCatalogItem的解析程序如下所示

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
}

{
    "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\"",
    ]
}

这给我带来了一个错误：

调用com.amazonaws.deepdish.transform.util.TransformUtils类中的方法“toString”引发异常java.lang.IllegalArgumentException:在…处的参数数目错误。

如果我这样做：

{
    "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\"",
    ]
}

{
    "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\"",
    ]
}

这给我带来了一个错误：

无法分析JSON文档：“意外字符（'c'（代码99））：在…处需要逗号分隔数组项\n

如果我这样做：

{
    "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\"",
    ]
}

{
    "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\"",
    ]
}

然后我得到了一个有意义的错误：

RDSHttp:{“消息”：“错误：类型json的输入语法无效\n详细信息：标记\“connectionType\”无效。\n位置：222\n其中：json数据，第1行：{connectionType…”

但是，当我在解析器中硬编码JSON时，它可以工作：

{
    "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，我如何将{connectionType=ftth，capacity=1}转换为{“connectionType”：“ftth”，“capacity”：1}？我做错了什么，还是遗漏了什么？非常感谢您的帮助。

解决方案1：

多亏了@cyberwombat，我才能够解决这个问题。如果有人需要，我会将此作为参考发布

我的

serviceConfig

对象不是固定的，可能会随着时间而改变，因此我修改了我的解析器，使其更通用，它看起来像这样：

#set($serviceConfigMap = {})

#foreach($key in $ctx.args.input.serviceConfig.keySet())
    $util.qr($serviceConfigMap.put("$key", $ctx.args.input.serviceConfig.get($key)))
#end

#set($serviceConfigMap = $util.toJson($serviceConfigMap))

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

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

旧解决方案：

这是我以前解决这个问题的方法

我将解析器转换为管道，并在NodeJS中创建了一个简单的Lambda函数来字符串化JSON对象。我的Lambda函数如下所示：

exports.handler = (event, context, callback) => {

    const response = {
        statusCode: 200,
        body: JSON.stringify(event.input.serviceConfig).replace(/\"/g, '\\\"'),
    };
    callback(null, response)
};

这就是serviceConfig现在的样子，也是我想要的：

{\"connectionType\":\"ftth\",\"maxUploadCapacity\":1}"

---

现在，我可以在解析器的SQL语句中轻松地使用它。

您可以像这样构建JSON变量：

#set($serviceConfigMap = {})

#foreach($key in $ctx.args.input.serviceConfig.keySet())
    $util.qr($serviceConfigMap.put("$key", $ctx.args.input.serviceConfig.get($key)))
#end

#set($serviceConfigMap = $util.toJson($serviceConfigMap))

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

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

并在查询中插入：

{
    "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，上面的内容有点挑战性，但我认为使用

escapeJavaScript

就可以了

或直接：

{
    "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\"",
    ]
}

---

你是最棒的。你的解决方案成功了！！因为我的JSON不只是固定在连接类型和容量键上，所以我对你的解决方案做了一些修改。如果有人需要，我会发布我的解决方案仅供参考。非常感谢！！