AppSync with DynamoDB (GraphQL) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a GraphQL query that fetches all items from a DynamoDB table.

DynamoDB

query ListItems {
  listItems [1] {
    items {
      id
      name
    }
  }
}

Drag options to blanks, or click blank then click option'

A()

B{filter: {}}

C(limit: 10)

D(id: "123")

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting parentheses causes syntax errors.

Passing unnecessary arguments when none are required.

The listItems query requires parentheses even if no arguments are passed, so () is correct.

2fill in blank

medium

Complete the mutation to add a new item with id and name fields.

DynamoDB

mutation AddItem {
  createItem(input: [1]) {
    id
    name
  }
}

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A"id: 1, name: Item1"

B{id: "1", name: "Item1"}

C[id, name]

Did, name

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings instead of objects for input.

Using arrays or comma-separated values without braces.

The input argument must be an object with field names and values, so {id: "1", name: "Item1"} is correct.

3fill in blank

hard

Fix the error in the resolver mapping template to get an item by id.

DynamoDB

{
  "version": "2018-05-29",
  "operation": "[1]",
  "key": {
    "id": $util.dynamodb.toDynamoDBJson($ctx.args.id)
  }
}

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APutItem

BScan

CQuery

DGetItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using PutItem instead of GetItem causes wrong operation.

Using Query without specifying key conditions.

To get a single item by key, the operation must be GetItem.

4fill in blank

hard

Fill both blanks to create a resolver that queries items with a filter expression.

DynamoDB

{
  "version": "2018-05-29",
  "operation": "[1]",
  "filter": {
    "expression": "[2]",
    "expressionValues": {
      ":val": $util.dynamodb.toDynamoDBJson($ctx.args.filterValue)
    }
  }
}

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AScan

BQuery

Cid = :val

Dname = :val

Attempts:

3 left

💡 Hint

Common Mistakes

Using Query without key condition causes errors.

Incorrect filter expression syntax.

Scan operation supports filter expressions like name = :val to filter items.

5fill in blank

hard

Fill all three blanks to define a mutation resolver that updates an item attribute.

DynamoDB

{
  "version": "2018-05-29",
  "operation": "[1]",
  "key": {
    "id": $util.dynamodb.toDynamoDBJson($ctx.args.id)
  },
  "update": {
    "expression": "set [2] = :val",
    "expressionValues": {
      ":val": $util.dynamodb.toDynamoDBJson($ctx.args.newValue)
    }
  },
  "condition": "[3]"
}

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AUpdateItem

BattributeName

Cattribute_exists(id)

DPutItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using PutItem overwrites the whole item.

Missing condition can cause errors if item does not exist.

UpdateItem is the operation to update attributes. The expression sets the attributeName to a new value. The condition ensures the item exists.