无效的UpdateExpression:运算符或函数的操作数类型错误;运算符:ADD,操作数类型:LIST [英] Invalid UpdateExpression: Incorrect operand type for operator or function; operator: ADD, operand type: LIST
问题描述
我试图在UpdateExpression中使用ADD将电子邮件字符串添加到字符串集(代码如下),但遇到此异常:无效的UpdateExpression:运算符或函数的操作数类型错误;
I tried to use ADD in UpdateExpression to add an email string into a string set , code as below , but hit this exception : Invalid UpdateExpression: Incorrect operand type for operator or function; operator: ADD, operand type: LIST.
我认为关键是我需要一种将类型更改为字符串集的方法,但不确定是什么
I think the point is that I need a way to change the type into "string set" , but not sure what is the semantic to achieve that.
response = wishesTable.update_item(
Key={
'title': wishTitle,
'userMail': wishUsermail
},
UpdateExpression='ADD whoLikeList :my_value',
ExpressionAttributeValues={
":my_value": [userEmail]
},
ReturnValues="UPDATED_NEW"
)
推荐答案
通过引用TypeSerializer类( http ://boto3.readthedocs.io/zh-CN/latest/_modules/boto3/dynamodb/types.html
)
By referring to TypeSerializer class ( http://boto3.readthedocs.io/en/latest/_modules/boto3/dynamodb/types.html )
将代码更改为
response = wishesTable.update_item(
Key={
'title': wishTitle,
'userMail': wishUsermail
},
UpdateExpression='ADD whoLikeList :my_value',
ExpressionAttributeValues={
":my_value": set([userEmail])
},
ReturnValues="UPDATED_NEW"
)
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