Schema definitions in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this JSON schema validation?

Given this JSON schema and data, what will be the validation result?

Rest API

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "name": {"type": "string"},
    "age": {"type": "integer", "minimum": 0}
  },
  "required": ["name", "age"]
}

Data:
{
  "name": "Alice",
  "age": -5
}

A Invalid: age is less than minimum 0

B Valid

C Invalid: name is missing

D Invalid: age is not an integer

💡 Hint

Check the 'minimum' constraint for the 'age' property.

The 'age' property must be an integer greater than or equal to 0. The data has age -5, which violates the minimum constraint.

🧠 Conceptual

intermediate

Which JSON schema keyword restricts the allowed properties in an object?

In JSON schema, which keyword limits the properties that can appear in an object to only those specified?

A "required"

B "additionalProperties"

C "properties"

D "patternProperties"

💡 Hint

It controls whether extra properties beyond those listed are allowed.

The 'additionalProperties' keyword controls whether properties not listed in 'properties' are allowed or not.

🔧 Debug

advanced

Identify the error in this JSON schema snippet

What is wrong with this JSON schema snippet that defines an array?

Rest API

{
  "type": "array",
  "items": {
    "type": "string"
  },
  "minItems": "2"
}

A "minItems" should be a number, not a string

B "items" must be an array, not an object

C "type" must be "object" for arrays

D "minItems" is not a valid keyword

💡 Hint

Check the data type of the value for 'minItems'.

'minItems' expects a number, but here it is given as a string "2", which is invalid.

📝 Syntax

advanced

Which option correctly defines a schema for a nullable string?

You want a property that can be either a string or null. Which JSON schema snippet is correct?

A { "anyOf": ["string", "null"] }

B { "type": "string|null" }

C { "type": "string", "nullable": true }

D { "type": ["string", "null"] }

💡 Hint

The 'type' keyword can accept an array of types.

The correct way to allow multiple types is to use an array for 'type'. Option D is valid JSON schema syntax.

🚀 Application

expert

How many properties will be valid with this schema?

Given this schema, how many properties can a valid object have?

Rest API

{
  "type": "object",
  "properties": {
    "a": {"type": "string"},
    "b": {"type": "number"}
  },
  "additionalProperties": false
}

A At least 2 properties required

B Any number of properties allowed

C Only 2 properties: 'a' and 'b'

D Exactly 1 property allowed

💡 Hint

Check the effect of 'additionalProperties': false.

With 'additionalProperties': false, only the properties listed under 'properties' are allowed. Here, only 'a' and 'b' are valid.