Info argument in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the GraphQL query info argument in a resolver.

GraphQL

resolve(parent, args, context, [1]) { return args.id; }

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

Ainfo

Broot

Ccontext

Dparams

Attempts:

3 left

💡 Hint

Common Mistakes

Using context instead of info to access query details.

Confusing root or parent with info argument.

The info argument provides details about the GraphQL query, such as the field name and schema.

2fill in blank

medium

Complete the code to get the field name from the info argument inside a resolver.

GraphQL

const fieldName = [1].fieldName;

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

Aargs

Bcontext

Cinfo

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to get fieldName from args or context which do not have it.

The info argument contains the fieldName property which tells which field is being resolved.

3fill in blank

hard

Fix the error in accessing the selection set from the info argument.

GraphQL

const selections = info.fieldNodes[0].[1].selections;

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

AselectionSet

Bselection

Cfields

Dnodes

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'selection' instead of 'selectionSet' causes undefined errors.

Trying to access 'fields' or 'nodes' which do not exist.

The fieldNodes[0] object has a selectionSet property that contains the selections of the query.

4fill in blank

hard

Fill both blanks to extract the names of selected fields from the info argument.

GraphQL

const fieldNames = info.fieldNodes[0].[1].selections.map(sel => sel.[2].value);

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

AselectionSet

Bname

CfieldName

Dfields

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fieldName' instead of 'name' inside the map function.

Using 'fields' which is not a valid property here.

The selectionSet contains the selections, and each selection has a name property for the field name.

5fill in blank

hard

Fill all three blanks to check if a specific field is requested in the query using the info argument.

GraphQL

const selections = info.fieldNodes[0].[1].selections;
const requestedFields = selections.map(sel => sel.[2].value);
const hasField = requestedFields.includes([3]);

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

AselectionSet

Bname

C'email'

D'id'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' instead of 'name.value' causes errors.

Checking for a field name without quotes or wrong quotes.

We access the selectionSet to get selections, then map to get each field's name.value. Finally, we check if the field 'email' is included.

Practice

1. What is the purpose of the info argument in a GraphQL resolver?

easy

A. It stores the database connection details.

B. It contains the user's authentication token.

C. It tells the resolver which fields the client requested.

D. It defines the schema of the GraphQL server.

Solution

1. Step 1: Understand the role of resolver arguments

   Resolvers receive arguments like parent, args, context, and info. Each has a specific role.

2. Step 2: Identify what info provides

   The info argument contains details about the query, including which fields the client requested.

3. Final Answer:

   It tells the resolver which fields the client requested. -> Option C

4. Quick Check:

   Info argument = requested fields [OK]

Hint: Info shows requested fields to optimize data fetching [OK]

Common Mistakes:

• Confusing info with context or args
• Thinking info holds authentication data
• Assuming info defines schema

2. Which of the following is the correct way to include the info argument in a GraphQL resolver function?

easy

A. resolver(parent, args, context, info) { ... }

B. resolver(args, parent, info, context) { ... }

C. resolver(context, info, args, parent) { ... }

D. resolver(info, parent, args, context) { ... }

Solution

1. Step 1: Recall the standard resolver signature

   The standard order is (parent, args, context, info) in GraphQL resolvers.

2. Step 2: Match the correct order

   resolver(parent, args, context, info) { ... } matches this order exactly, making it the correct syntax.

3. Final Answer:

   resolver(parent, args, context, info) { ... } -> Option A

4. Quick Check:

   Resolver args order = parent, args, context, info [OK]

Hint: Remember resolver args order: parent, args, context, info [OK]

Common Mistakes:

• Mixing up the order of arguments
• Placing info before context
• Omitting info argument

3. Given this resolver snippet, what will info.fieldNodes[0].selectionSet.selections.map(f => f.name.value) return if the client queries { user { id name } }?

medium

A. ["id", "name"]

B. ["user"]

C. ["id"]

D. An empty array []

Solution

1. Step 1: Understand the query structure

   The client requests the fields id and name inside user.

2. Step 2: Analyze the info.fieldNodes access

   info.fieldNodes[0].selectionSet.selections lists the fields requested inside user, which are id and name.

3. Final Answer:

   ["id", "name"] -> Option A

4. Quick Check:

   info.fieldNodes selections = requested fields [OK]

Hint: info.fieldNodes lists requested fields inside current resolver [OK]

Common Mistakes:

• Returning parent field name instead of subfields
• Confusing selectionSet with fieldNodes
• Expecting only one field instead of all requested

4. You wrote this resolver: function resolver(parent, args, context) { return info.fieldNodes; }. Why does this cause an error?

medium

A. You cannot access fieldNodes inside resolvers.

B. The resolver is missing the info argument in its parameters.

C. The info argument must be the first parameter.

D. Resolvers cannot return objects like fieldNodes.

Solution

1. Step 1: Check resolver parameters

   The resolver only has three parameters: parent, args, context. It lacks the fourth parameter info.

2. Step 2: Understand usage of info

   Since info is not declared, trying to use it causes a reference error.

3. Final Answer:

   The resolver is missing the info argument in its parameters. -> Option B

4. Quick Check:

   Missing info param = error [OK]

Hint: Always include info as fourth parameter to use it [OK]

Common Mistakes:

• Forgetting to add info parameter
• Assuming info is global or in context
• Misordering resolver parameters

5. You want your resolver to return only the fields requested by the client to save resources. Which approach using the info argument is best?

hard

A. Fetch all fields but filter results after sending to client.

B. Ignore info and always fetch all fields from the database.

C. Use args to guess which fields the client wants.

D. Use info.fieldNodes to find requested fields and fetch only those from the database.

Solution

1. Step 1: Understand the goal

   The goal is to fetch only requested fields to save resources.

2. Step 2: Use info to get requested fields

   info.fieldNodes provides the exact fields the client asked for, so you can fetch only those.

3. Step 3: Compare options

   Use info.fieldNodes to find requested fields and fetch only those from the database. uses info correctly. Options B, C, and D either waste resources or guess incorrectly.

4. Final Answer:

   Use info.fieldNodes to find requested fields and fetch only those from the database. -> Option D

5. Quick Check:

   Use info to fetch requested fields only [OK]

Hint: Fetch only requested fields using info to save resources [OK]

Common Mistakes:

• Fetching all data regardless of request
• Using args instead of info for fields
• Filtering after fetching all data