Field selection in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select the user's name field.

GraphQL

{ user { [1] } }

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

Aage

Bemail

Cname

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting a field that does not exist like 'username'.

Using a field unrelated to the user's name.

The name field is selected to get the user's name.

2fill in blank

medium

Complete the code to select the user's email field.

GraphQL

{ user { [1] } }

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

Aphone

Bemail

Cid

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting 'phone' instead of 'email'.

Using 'username' which is not defined.

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

3fill in blank

hard

Fix the error in the query to select the user's id field.

GraphQL

{ user { [1] } }

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

Aid

Bname

Cemail

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ID' with uppercase letters which is case sensitive.

Selecting 'age' instead of 'id'.

The id field uniquely identifies the user and must be selected correctly.

4fill in blank

hard

Fill both blanks to select the user's name and email fields.

GraphQL

{ user { [1] [2] } }

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

Aname

Bemail

Cid

Dphone

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting 'id' or 'phone' instead of 'email'.

Using incorrect field names or misspellings.

Selecting both name and email fields returns the user's name and email.

5fill in blank

hard

Fill all three blanks to select the user's id, name, and email fields.

GraphQL

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

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

Aid

Bname

Cemail

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Including 'age' instead of 'email'.

Misspelling any of the field names.

Selecting id, name, and email fields returns the user's unique id, name, and email address.

Practice

1. What does field selection in GraphQL allow you to do?

easy

A. Encrypt data before sending it

B. Automatically update the database schema

C. Choose only the data fields you want to receive

D. Create new database tables

Solution

1. Step 1: Understand the purpose of field selection

   Field selection lets you specify exactly which fields you want in your query response.

2. Step 2: Compare options with the concept

   Only Choose only the data fields you want to receive describes choosing specific data fields, which matches field selection.

3. Final Answer:

   Choose only the data fields you want to receive -> Option C

4. Quick Check:

   Field selection = Choose specific fields [OK]

Hint: Field selection means picking only needed data fields [OK]

Common Mistakes:

• Confusing field selection with schema changes
• Thinking it encrypts data
• Assuming it creates database tables

2. Which of the following is the correct GraphQL syntax to select the fields id and name from a user?

easy

A. { user: id, name }

B. { user(id, name) }

C. query user { id, name }

D. { user { id, name } }

Solution

1. Step 1: Recall GraphQL field selection syntax

   Fields are selected inside curly braces after the type name, separated by commas or spaces.

2. Step 2: Check each option's syntax

   { user { id, name } } correctly uses braces and field names inside user. Others have syntax errors or wrong structure.

3. Final Answer:

   { user { id, name } } -> Option D

4. Quick Check:

   Correct field selection syntax = { user { id, name } } [OK]

Hint: Use braces to nest fields inside the type name [OK]

Common Mistakes:

• Using colon instead of braces for fields
• Omitting braces around fields
• Trying to pass fields as function arguments

3. Given this GraphQL query:

{ book { title author { name } } }

What fields will be returned in the response?

medium

A. { "book": { "title": "...", "author": { "name": "..." } } }

B. { "book": { "title": "...", "author": "..." } }

C. { "book": { "author": { "name": "..." } } }

D. { "book": { "title": "..." } }

Solution

1. Step 1: Analyze the query structure

   The query requests title and nested author with its name field.

2. Step 2: Determine the response shape

   The response will include title and an author object containing name.

3. Final Answer:

   { "book": { "title": "...", "author": { "name": "..." } } } -> Option A

4. Quick Check:

   Nested fields return nested objects [OK]

Hint: Nested fields return nested objects in response [OK]

Common Mistakes:

• Expecting author as a string instead of object
• Missing requested fields in response
• Ignoring nested field structure

4. Identify the error in this GraphQL query:

{ user { id name, } }

medium

A. Trailing comma after last field causes syntax error

B. Missing parentheses after user

C. Fields must be quoted strings

D. Curly braces are not allowed inside queries

Solution

1. Step 1: Check field list syntax

   GraphQL does not allow a comma after the last field in a selection set.

2. Step 2: Verify other syntax rules

   No parentheses needed after user, fields are unquoted, and braces are required.

3. Final Answer:

   Trailing comma after last field causes syntax error -> Option A

4. Quick Check:

   No trailing commas in field lists [OK]

Hint: No trailing commas after last field in selection [OK]

Common Mistakes:

• Adding commas after last field
• Adding unnecessary parentheses
• Quoting field names

5. You want to fetch a list of products with only their id and price, but each product also has a nested manufacturer with name and location. How do you write a GraphQL query to select only id, price, and the manufacturer's name (not location)?

hard

A. { products { id price manufacturer { name location } } }

B. { products { id price manufacturer { name } } }

C. { products { id price manufacturer name } }

D. { products { id price, manufacturer: { name } } }

Solution

1. Step 1: Identify required fields

   We need id, price, and nested manufacturer with only name.

2. Step 2: Write correct nested field selection

   { products { id price manufacturer { name } } } correctly nests name inside manufacturer and excludes location.

3. Step 3: Check other options for errors

   { products { id price manufacturer { name location } } } includes unwanted location. { products { id price manufacturer name } } incorrectly places name outside manufacturer. { products { id price, manufacturer: { name } } } has invalid colon syntax.

4. Final Answer:

   { products { id price manufacturer { name } } } -> Option B

5. Quick Check:

   Select only needed nested fields [OK]

Hint: Nest only needed fields inside parent fields [OK]

Common Mistakes:

• Selecting unwanted nested fields
• Placing nested fields outside their parent
• Using colon instead of braces for nesting