If you are using an older version of Jackson API e.g. In Jackson 2.x, the reside in package, hence you need to import it as : If you compile and run your program again it will work fine. any property for which we don’t have a corresponding field in the EBook class will be ignored. We have just annotated a whole model class as = true), which mean any unknown property in JSON String i.e. You can solve this problem and prevent this error by using annotation as shown below: = true) This means Jackson is not able to find any field in your EBook class for “edition” property in JSON and hence it’s throwing the UnrecognizedPropertyException error. Something like :Įxception in thread “main” .exc.UnrecognizedPropertyException: Unrecognized field “edition” (class EBook), not marked as ignorable (3 known properties:, “title”, “price”, “author”])”
If tomorrow, I add a new field called “edition” in the JSON then parsing of this JSON will fail with the UnrecognizedPropertyException error. Suppose I have following JSON, which represents my favorite book, Effective Java 3rd Edition, a must read books for every Java developer in 2018, and a Java model class in my project: You can use this approach if you want to ignore unknown properties only for that Model class, but this is preferred approach because it provides you more control. Which means if there is a new field is added tomorrow on JSON which represent your Model then Jackson will not throw UnrecognizedPropertyException while parsing JSON in Java. Ignoring unknown properties using you are creating a Model class to represent the JSON in Java, then you can annotate the class with = true) to ignore any unknown field.
Jackson annotations how to#
You will see both approaches in this article and learn how to use them and when to use JsonIgnoreProperties and when to ignore unknown fields in JSON globally at the ObjectMapper level. Jackson API provides two ways to ignore unknown fields, first at the class level using annotation and second at the ObjectMapper level using configure() method. The issue could have simply been avoided if he was familiar with Jackson library in a little bit more detail.
Jackson annotations update#
The developer chooses to ignore the update because we weren’t interested in that field but he failed to foresee that it will impact the JSON parsing.Īnyway, it was our fault that we didn’t review code properly and allowed him to release his code into production without handling unknown files. The code worked fine for months but it broke as soon as source system added a new field is added to REST API.
I have faced this issue when a developer shipped the code to consume data from REST API without proper handling unknown fields. This is troublesome and can cause problems in production if you are not aware. For example, if you are consuming JSON from a REST Web Service and tomorrow they added a new field into JSON then your code will break because Jackson will throw UnrecognizedPropertyException and stop parsing JSON. your Java class doesn’t have all the field corresponding to all JSON properties. One of the common problem while parsing JSON in Java using Jackson API is that it fails when your JSON contains unknown properties i.e.
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