Expressions with SDK helpers in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a condition expression that checks if the attribute "status" equals "active".

DynamoDB

const condition = Attr('status').[1]('active');

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Aeq

Bne

Clt

Dcontains

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ne' which means 'not equal' instead of 'eq'.

Using 'contains' which checks for substring, not equality.

The eq method creates a condition expression that checks if the attribute equals the given value.

2fill in blank

medium

Complete the code to create a filter expression that checks if the attribute "age" is greater than 30.

DynamoDB

const filter = Attr('age').[1](30);

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Alt

Bgt

Ceq

DbeginsWith

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'lt' which means 'less than' instead of 'greater than'.

Using 'beginsWith' which is for strings, not numbers.

The gt method creates a condition expression that checks if the attribute is greater than the given value.

3fill in blank

hard

Fix the error in the code to check if the attribute "name" begins with "A".

DynamoDB

const condition = Attr('name').[1]('A');

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Aeq

Bcontains

CbeginsWith

Dgt

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'contains' which checks anywhere in the string, not just the start.

Using 'eq' which checks for exact match.

The beginsWith method checks if a string attribute starts with the given substring.

4fill in blank

hard

Fill both blanks to create a condition expression that checks if "score" is between 50 and 100.

DynamoDB

const condition = Attr('score').[1](50).[2](100);

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Abetween

Beq

Cne

Dgt

Attempts:

3 left

💡 Hint

Common Mistakes

Using different methods for the two values instead of 'between'.

Using 'eq' or 'ne' which check equality, not range.

The between method is used with two values to check if an attribute is within a range.

5fill in blank

hard

Fill all three blanks to create a filter expression that checks if "category" equals "books" and "price" is less than 20.

DynamoDB

const filter = Attr([1]).[2]('books').and(Attr([3]).lt(20));

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A'category'

Beq

C'price'

Dgt

Attempts:

3 left

💡 Hint

Common Mistakes

Using attribute names without quotes.

Using 'gt' instead of 'lt' for price comparison.

Using wrong method instead of 'eq' for equality.

We check if the 'category' attribute equals 'books' using eq, and if 'price' is less than 20 using lt.