DynamoDB 更新操作中的 ConditionExpression 给出未知错误

Question

我运行通过 DynamoDB 中的很多项目 table 如果项目包含某个字段（它是一个对象），我想在该对象上设置一些属性在那个领域。

我已经尝试了两种代码变体，但它们都给了我以下未指定的错误

{
    "errorType": "ConditionalCheckFailedException",
    "errorMessage": "The conditional request failed",
    "code": "ConditionalCheckFailedException",
    "message": "The conditional request failed",
    "time": "2020-08-29T11:44:11.703Z",
    "requestId": "IAN8A31FN2F1HR0ORT1RMTH5ENVV4KQNSO5AEMVJF66Q9ASUAAJG",
    "statusCode": 400,
    "retryable": false,
    "retryDelay": 26.45456917481479,
    "stack": [
        "ConditionalCheckFailedException: The conditional request failed",
        "    at Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:51:27)",
        "    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)"
    ]
}

这是具有命名属性的代码


          const itemParams = {
            TableName: process.env.vehiclesTableName,
            Key: { vehicleId },
            UpdateExpression:
              'set #learned.#versionId = :versionId, #learned.#fileFormat = :fileFormat',
            ExpressionAttributeValues: {
              ':versionId': VersionId,
              ':fileFormat': fileFormat,
            },
            ConditionExpression: 'attribute_exists(#learned)',
            ExpressionAttributeNames: {
              '#learned': 'learned',
              '#versionId': 'versionId',
              '#fileFormat': 'fileFormat',
            },
          }
          await db.update(itemParams).promise()

并且没有命名属性

          const itemParams = {
            TableName: process.env.vehiclesTableName,
            Key: { vehicleId },
            UpdateExpression:
              'set learned.versionId = :versionId, learned.fileFormat = :fileFormat',
            ExpressionAttributeValues: {
              ':versionId': VersionId,
              ':fileFormat': fileFormat,
            },
            ConditionExpression: 'attribute_exists(learned)',
          }
          await db.update(itemParams).promise()

它们的行为相同。

Answer 1

您看到的异常实际上是预期的行为，表明条件未计算为真。来自 documentation:

ConditionalCheckFailedException

Message: The conditional request failed.

You specified a condition that evaluated to false. For example, you might have tried to perform a conditional update on an item, but the actual value of the attribute did not match the expected value in the condition.

当您遇到 ConditionalCheckFailedException 异常时，您显然是在尝试更新没有 learned 属性的项目。

DynamoDB 更新操作中的 ConditionExpression 给出未知错误

ConditionExpression in DynamoDB update operation gives unknown error

amazon-dynamodb

dynamodb-queries