There are different ways to show errors in nested JSON in a REST API, but one commonly used approach is to use HTTP error codes and error objects in the response body.
For example, if a client sends a request to create a resource with invalid nested data, the server can respond with a 400 Bad Request error code and an error object in the response body that describes the specific error(s) and their location in the nested data.
The error object can be structured as a JSON object with one or more key-value pairs, where the key represents the error type and the value is a human-readable message or a code that can be used for localization or automation. Here's an example:
{
"errors": [
{
"field": "name",
"message": "Name is required"
},
{
"field": "address.street",
"message": "Street is too short"
},
{
"field": "contacts[0].email",
"code": "invalid.email",
"params": {
"format": "RFC822"
}
}
]
}
In this example, the errors array contains three error objects that correspond to three different nested fields. The first error object has a simple message, the second error object indicates the nested field with a dot notation, and the third error object has an error code and additional parameters to describe the error in more detail.
By providing detailed error information in the response body, clients can quickly identify and fix errors without having to guess or experiment. This can improve the usability and reliability of your REST API.