GraphQL - Resolvers
If a GraphQL query returns null for a field that exists in both the schema and the data source, which default resolver-related issue should you investigate?
If a GraphQL query returns null for a field that exists in both the schema and the data source, which default resolver-related issue should you investigate?
medium📝 Debug Q7 of 15
Step-by-Step Solution
Solution:
Step 1: Understand default resolver mechanics
The default resolver accesses the field on the parent object.Step 2: Identify cause of null return
If the parent object is null or undefined, the default resolver cannot retrieve the field value, resulting in null.Step 3: Debugging step
Check if the parent object passed down is valid and contains the expected data.Final Answer:
Check if the parent object passed to the default resolver is undefined or null. -> Option DQuick Check:
Null parent object causes default resolver to return null [OK]
Quick Trick: Null parent object causes default resolver to return null [OK]
Common Mistakes:
- Assuming schema non-nullable fields prevent null returns
- Thinking __typename affects default resolver
- Blaming GraphQL version for resolver issues
Master "Resolvers" in GraphQL
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