Column types and constraints in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a string column named 'username' in a Flask SQLAlchemy model.

Flask

username = db.Column(db.[1](50), nullable=False)

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

AInteger

BString

CBoolean

DFloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using Integer or Boolean instead of String for text data.

Forgetting to specify max length for String.

The String type defines a text column with a max length. Here, 50 means max 50 characters.

2fill in blank

medium

Complete the code to add a primary key constraint to the 'id' column.

Flask

id = db.Column(db.Integer, [1]=True)

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

Aunique

Bnullable

Cprimary_key

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'unique=True' instead of 'primary_key=True'.

Forgetting to set primary_key on the id column.

The primary_key=True marks this column as the table's primary key.

3fill in blank

hard

Fix the error in the code to make the 'email' column unique and not nullable.

Flask

email = db.Column(db.String(120), unique=[1], nullable=[2])

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

ATrue

BFalse

CNone

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting nullable=True which allows empty emails.

Not setting unique=True to prevent duplicates.

Both unique and nullable should be set to True and False respectively to enforce uniqueness and non-null values. Here, unique=True and nullable=False.

4fill in blank

hard

Fill both blanks to define a column 'age' that stores integers and cannot be null.

Flask

age = db.Column(db.[1], [2]=False)

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

AInteger

BString

Cnullable

Dprimary_key

Attempts:

3 left

💡 Hint

Common Mistakes

Using String type for age.

Forgetting to set nullable=False.

The 'age' column should be an Integer type and must not allow null values, so nullable=False.

5fill in blank

hard

Fill all three blanks to define a 'created_at' column with DateTime type, defaulting to current time, and not nullable.

Flask

created_at = db.Column(db.[1], default=[2], [3]=False)

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

ADateTime

Bfunc.now()

Cnullable

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of DateTime.

Not setting default to current time.

Allowing nullable=True which can cause missing timestamps.

The 'created_at' column uses DateTime type, defaults to the current time using func.now(), and cannot be null with nullable=False.