JsonMappingException class

The error the JSON mapper throws when JSON cannot be turned into the requested type, or a value cannot be written as JSON.

Typical causes: text that is not JSON, a missing required property, a value of the wrong type, a constructor that threw. The path says where in the document the problem is, so the message can go back to whoever sent the JSON. Catch it where you read JSON from outside; the web starter turns it into a 400 response for request bodies.

// Reject a bad upload with a message naming the field.
try {
  mapper.readValue<Order>(json);
} on JsonMappingException catch (error) {
  log.warning(error); // items[2].price: expected a number, got "abc"
}

Spring (Java):

catch (JsonMappingException e) { e.getPathReference(); }

Implemented types

• Exception

Constructors

JsonMappingException(String message, {String path = '', Object? cause})

A problem described by message at path (empty for the root), caused by cause.

Properties

cause → Object?

The underlying error, such as a FormatException for invalid JSON or what a constructor threw; null when there is none.

final

hashCode → int

The hash code for this object.

no setter, inherited

message → String

What went wrong, without the path.

final

path → String

Where the problem is, such as items[2].price; empty for the whole value.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

override

Operators

operator ==(Object other) → bool

The equality operator.

inherited