Why Am I Getting a \'Failed to Bounce to Type\' Error When Mapping Firebase JSON to Java Objects Using Jackson?

Why Am I Getting a "Failed to Bounce to Type" Error When Converting Firebase JSON to Java Objects?

Introduction

This error occurs during the conversion of Firebase JSON into Java objects using the Jackson library. It indicates that Jackson is unable to map the JSON properties to your Java class.

Solution

Ensure Java Class Properties Match JSON Properties

First, ensure that your Java class properties exactly match the JSON property names, including capitalization. Additionally, public getters should exist for each property.

Utilize @JsonIgnoreProperties Annotation

If your Java class does not include mappings for all JSON properties, you can use the @JsonIgnoreProperties annotation to ignore specific properties during the conversion.

Leverage @JsonIgnore Annotation

For properties you wish to include in your Java class but not serialize back to JSON, you can use the @JsonIgnore annotation to indicate they should be ignored.

Example

Consider the following Firebase JSON structure:

{
  "users": {
    "-Jx5vuRqItEF-7kAgVWy": {
      "handle": "puf",
      "name": "Frank van Puffelen",
      "soId": 209103
    }
  }
}

To convert this JSON into a Java object, define the following class:

private static class User {
  private String handle;
  private String name;

  public String getHandle() { return handle; }
  public String getName() { return name; }
}

When adding the @JsonIgnoreProperties annotation to ignore the soId property, the code becomes:

@JsonIgnoreProperties({"soId"})
private static class User {
  private String handle;
  private String name;

  public String getHandle() { return handle; }
  public String getName() { return name; }
}

Or, to completely ignore any unmatched properties, use the following annotation:

@JsonIgnoreProperties(ignoreUnknown = true)
private static class User {
  ...
}

This allows Jackson to ignore properties in the JSON that do not have corresponding Java class properties.

The above is the detailed content of Why Am I Getting a \'Failed to Bounce to Type\' Error When Mapping Firebase JSON to Java Objects Using Jackson?. For more information, please follow other related articles on the PHP Chinese website!