AWS DynamoDB DocumentClient查询错误—一个或多个参数值无效:条件参数类型不匹配模式类型.<

Question

我有一个名为AccountXX的AWS DynamoDb表，它将具有JSON结构的项目存储为:

{
"id": "some id value", // also the partition key for the table
"name": "a name",
"email": "an email address",
"salt": [12, 3, ... ], // an array of random values
"hash": [1, 5, ... ],  // an array representing a hashed password
... // and some more attributes
}

在AccountXX表上有一个名为Account_email_hash_salt_gsi的全局二级索引，该索引具有分区键email，并具有hash, salt和id的附加属性。

当我发出以下AWS CLI命令时，我能够成功地查询表中的一个项目:

aws dynamodb query --table AccountXX 
--index-name Account_email_hash_salt_gsi 
--key-condition-expression "email = :emailValue" 
--expression-attribute-values file://values.json

values.json的内容为:

{":emailValue":{"S": "[e-mail]"}}

然而，当我使用AWS.DynamoDB.DocumentClient实例使用以下参数对象发出类似的调用时，我得到一个错误:

const params = {
TableName: accountTable,       // will be set to 'AccountXX'
IndexName: "Account_email_hash_salt_gsi",
KeyConditionExpression:"#email = :emailValue",
ExpressionAttributeNames: {
"#email": "email"
},
ExpressionAttributeValues: {
":emailValue": {"S": loginToken.email}
},
ScanIndexForward: false
};

我得到的错误是:

ValidationException: One or more parameter values were invalid: Condition parameter type does not match schema type
at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:52:27)
at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/request.js:688:14)
at Request.transition (/var/runtime/node_modules/aws-sdk/lib/request.js:22:10)
at AcceptorStateMachine.runTo (/var/runtime/node_modules/aws-sdk/lib/state_machine.js:14:12)
at /var/runtime/node_modules/aws-sdk/lib/state_machine.js:26:10
at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:38:9)
at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:690:12)
at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:116:18)

我还尝试使用修改后的参数对象，如下所示:

const params = {
TableName: accountTable,   // will be set to 'AccountXX'
IndexName: "Account_email_hash_salt_gsi",
KeyConditionExpression:"#email = :emailValue",
ExpressionAttributeNames: {
"#email": "email"
},
ExpressionAttributeValues: {
":emailValue": loginToken.email   // directly using string type
},
ScanIndexForward: false
};

在这种情况下，我得到以下错误:

ValidationException: ExpressionAttributeValues must not be empty
at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:52:27)
at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/request.js:688:14)
at Request.transition (/var/runtime/node_modules/aws-sdk/lib/request.js:22:10)
at AcceptorStateMachine.runTo (/var/runtime/node_modules/aws-sdk/lib/state_machine.js:14:12)
at /var/runtime/node_modules/aws-sdk/lib/state_machine.js:26:10
at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:38:9)
at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:690:12)
at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:116:18)

在这两种情况下，我的DynamoDB DocumentClient查询发出为:

const data = await dynamo.query(params).promise();

我应该做些什么来修复params对象，以便我能够成功地查询表?

Answer 1

找到并修复了问题。问题不在于DynamoDB查询或参数构造。根本原因是Lambda传递POST请求体的问题，处理程序错误地处理它。处理程序缺少JSON.parse(event.body)，因此loginToken是一个字符串。因此，loginToken.email被求值为空，导致查询失败。

顺便说一句，我发现在另一个类似问题的回答中提到的Amazon NoSQL Workbench工具在探索查询和使用UI自动生成查询方面非常有帮助。我使用它来确保查询参数在语法上是正确的，然后在进行一些故障排除后能够找到根本原因。