Scan dynamodb table based on filter which is not present in all object-CodePudding

So I'm trying to filter my dynamoDb data based on role as you can see role attribute is present in some of the objects not in all


[
  {
    id: "7",
    email: '[email protected]',
    name: 'test1',
    age: '12',
  },
  {
    id: "8",
    email: '[email protected]',
    name: 'test2',
    age: '12',
  },
  {
    email: '[email protected]',
    name: 'test3',
    age: '12',
    test: 'test',
    role: 'ADMIN'
  },
  {
    email: '[email protected]',
    name: 'test4',
    age: '12',
    test: 'test',
    role: 'ADMIN'
  }
]

if I try to scan with email it works but if I try to scan with role its gives me error: Invalid FilterExpression: Attribute name is a reserved keyword; reserved keyword: role

I tried with code

let params = {
  TableName: 'tableName',
  FilterExpression: 'role =:role',
  ExpressionAttributeValues: { ':role': 'ADMIN' },
  expressionAttributeNames: { '#role': 'role' }
}
let result = await this.docClient.scan(params).promise();

and this

let params = {
  TableName: 'tableName',
  FilterExpression: 'attribute_not_exists(role)',
  ExpressionAttributeValues: { ':role': 'ADMIN' },
  expressionAttributeNames: { '#role': 'role' }
}
let result = await this.docClient.scan(params).promise();

both giving me same error

CodePudding user response：

I believe you had a typo in your first code snippet. FilterExpression: 'role =:role', should be FilterExpression: '#role =:role',.

So the following should work,

let params = {
  TableName: 'tableName',
  FilterExpression: '#role =:role',
  ExpressionAttributeValues: { ':role': 'ADMIN' },
  ExpressionAttributeNames: { '#role': 'role' }
}
let result = await this.docClient.scan(params).promise();