Why queries request specific data in GraphQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to request the user's name in a GraphQL query.

GraphQL

query { user { [1] } }

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

Aaddress

Bage

Cname

Demail

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a field that does not exist or is unrelated to the user's name.

The field name is requested to get the user's name specifically.

2fill in blank

medium

Complete the code to request the user's email in a GraphQL query.

GraphQL

query { user { [1] } }

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

Aemail

Bphone

Cusername

Dlocation

Attempts:

3 left

💡 Hint

Common Mistakes

Requesting unrelated fields like phone or location instead of email.

The field email is requested to get the user's email address.

3fill in blank

hard

Fix the error in the query to request the user's age correctly.

GraphQL

query { user { [1] } }

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

Aage

Bages

CuserAge

Dbirthday

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural or incorrect field names like ages or userAge.

The correct field to request the user's age is age. Other options are incorrect or do not exist.

4fill in blank

hard

Fill both blanks to request the user's name and email in the query.

GraphQL

query { user { [1] [2] } }

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

Aname

Bemail

Cage

Dlocation

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing unrelated fields like age or location.

Requesting name and email fields returns the user's name and email.

5fill in blank

hard

Fill all three blanks to request the user's name, email, and age in the query.

GraphQL

query { user { [1] [2] [3] } }

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

Aname

Bemail

Cage

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Including unrelated fields like address.

Requesting name, email, and age fields returns those specific user details.

Practice

1. Why does a GraphQL query request only specific fields instead of all data?

easy

A. To get only the data needed and avoid extra work

B. Because GraphQL cannot fetch all data at once

C. To make the query syntax simpler

D. Because databases only store partial data

Solution

1. Step 1: Understand GraphQL query purpose

   GraphQL lets you ask for exactly the data you want, no more.

2. Step 2: Reason about efficiency

   Requesting only needed fields saves time and resources by avoiding extra data transfer.

3. Final Answer:

   To get only the data needed and avoid extra work -> Option A

4. Quick Check:

   Specific data request = Efficiency [OK]

Hint: Remember: ask only what you need to save resources [OK]

Common Mistakes:

• Thinking GraphQL cannot fetch all data
• Believing syntax is simpler by requesting all fields
• Assuming databases store only partial data

2. Which of the following is the correct GraphQL query syntax to request only the name and age fields of a user?

easy

A. { user name age }

B. { user: name, age }

C. query user { name, age }

D. { user { name age } }

Solution

1. Step 1: Recall GraphQL query structure

   A query requests a field (like user) and inside braces lists requested subfields.

2. Step 2: Check each option's syntax

   { user { name age } } correctly nests name and age inside user. Others have syntax errors or wrong structure.

3. Final Answer:

   { user { name age } } -> Option D

4. Quick Check:

   Correct nesting = { user { name age } } [OK]

Hint: Fields must be inside braces after the parent field [OK]

Common Mistakes:

• Omitting braces around fields
• Using commas inside GraphQL queries
• Incorrect alias or colon usage

3. Given this GraphQL query:

{ book { title author { name } } }

What data will the query return?

medium

A. Only the book titles

B. All book and author details

C. Book titles and author names

D. Only author names

Solution

1. Step 1: Analyze requested fields

   The query asks for title of book and inside author it asks for name.

2. Step 2: Determine returned data

   It returns book titles plus the names of their authors only, no other details.

3. Final Answer:

   Book titles and author names -> Option C

4. Quick Check:

   Requested fields = title + author name [OK]

Hint: Look inside braces to see exactly what fields are requested [OK]

Common Mistakes:

• Assuming all author details are returned
• Thinking only book titles come back
• Confusing nested fields with flat fields

4. Identify the error in this GraphQL query:

{ user { id, name, email } }

medium

A. Missing query keyword

B. Commas between fields are not allowed

C. Braces are misplaced

D. Field names must be capitalized

Solution

1. Step 1: Check GraphQL field list syntax

   GraphQL fields inside braces should be space-separated without commas.

2. Step 2: Identify the error

   The commas between id, name, and email cause a syntax error.

3. Final Answer:

   Commas between fields are not allowed -> Option B

4. Quick Check:

   No commas in field lists [OK]

Hint: Separate fields by spaces, not commas [OK]

Common Mistakes:

• Using commas between fields
• Adding unnecessary keywords
• Capitalizing field names incorrectly

5. You want to fetch a list of users with their id, name, and only their email if it exists. Which GraphQL query correctly requests this conditional data?

hard

A. query($showEmail: Boolean!) { users { id name email @include(if: $showEmail) } }

B. { users { id name email @include(if: true) } }

C. { users { id name email @skip(if: false) } }

D. { users { id name email } }

Solution

1. Step 1: Understand conditional field inclusion

   GraphQL uses directives like @include with variables to conditionally request fields.

2. Step 2: Evaluate options

   query($showEmail: Boolean!) { users { id name email @include(if: $showEmail) } } uses a variable $showEmail to include email only if true, which matches the requirement.

3. Final Answer:

   query($showEmail: Boolean!) { users { id name email @include(if: $showEmail) } } -> Option A

4. Quick Check:

   Use @include with variable for conditional fields [OK]

Hint: Use @include with variables to request fields conditionally [OK]

Common Mistakes:

• Always requesting email without condition
• Using @include with fixed true/false instead of variables
• Confusing @skip and @include directives