如何使用 javascript 对象部分更新 DynamoDB 中的项目？

Question

I have items in a DynamoDB database table and I want to update an existing item but only a few attributes of it instead of everything. I know I can do that with for example AWS.DynamoDB.DocumentClient, using the update() function and passing UpdateExpression with the attributes I want to update in the params. I also know that I can loop through the properties of the javascript object and construct an update expression based on that but I suspect there must be an easier way to do this.

So instead of something like this (and having to implement the two fetch* functions):

const ddbDocClient = new AWS.DynamoDB.DocumentClient();
const params = {
  TableName: 'SomeTable',
  Key: { id: someId },
  UpdateExpression: fetchPropertiesOfAJavascriptObjectAndMakeAnExpressionStringOfThem(obj),
  ExpressionAttributeValues: fetchValuesOfAJavascriptObjectAndMakeAValuesStringOfThem(obj)
}
ddbDocClient.update(params, (err, data) => {/* do something */});

I would like to do something like

const ddbDocClient = new AWS.DynamoDB.DocumentClient();
const params = {
  TableName: 'SomeTable',
  Key: { id: someId },
  AttributesToUpdate: obj
}
ddbDocClient.update(params, (err, data) => {/* do something */});

Answer 1

You cannot do so directly using the low level API, as you need to set the UpdateExpression .

You would need to use an object mapper type client which is not directly available via the SDK but can be obtained here:

https://github.com/awslabs/dynamodb-data-mapper-js