[Solved] You wrote this input type:input UserInput { name: String, age: Int }and mutation:mutation createUser($input: UserInput!) { addUser(input:... | GraphQL

GraphQL - Mutations

You wrote this input type:

input UserInput { name: String, age: Int }

and mutation:

mutation createUser($input: UserInput!) { addUser(input: $input) { id } }

But when you run the mutation, you get an error: "Variable '$input' expected value of type 'UserInput!' but got null." What is the likely cause?

AThe input type must not have nullable fields

BYou did not provide the input variable when calling the mutation

CThe mutation name is incorrect

DYou used 'input' instead of 'user' as argument name

Step-by-Step Solution

Solution:

Step 1: Understand required input variables
The variable $input is required (due to !), so it cannot be null.
Step 2: Identify cause of null error
The error means the variable was not provided or was null when calling the mutation.
Final Answer:
You did not provide the input variable when calling the mutation -> Option B
Quick Check:
Required variable missing = null error [OK]

Quick Trick: Always provide required variables when calling mutations [OK]

Common Mistakes:

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