When Is the @JSONproperty Property Used and What Is It Used For

When is the @JsonProperty property used and what is it used for?

Here's a good example. I use it to rename the variable because the JSON is coming from a .Net environment where properties start with an upper-case letter.

public class Parameter {
  @JsonProperty("Name")
  public String name;
  @JsonProperty("Value")
  public String value; 
}

This correctly parses to/from the JSON:

"Parameter":{
  "Name":"Parameter-Name",
  "Value":"Parameter-Value"
}

What [JsonProperty] used for in c#?

Per the documentation: this is the json key that will be used when serializing/deserializing this object to/from a json string.

So, if the value of FileName is file.txt, the serialized result would be

{
    "fileName": "file.txt"
}

Different @JsonProperty config for READ and WRITE on same field?

You could use the getters and setters to get that extra customization. The get will act as READ and the set as WRITE. Note that you don't need the access properties or the field level annotation:

    public abstract class StandingMixIn {
        @JsonProperty(access = JsonProperty.Access.READ_ONLY)
        Integer positionNumber;
        
        // No annotation on the field
        String positionText;

        @JsonProperty(value = "positionText")
        public String getPositionText() {
            return positionText;
        }

        @JsonProperty(value = "position")
        public void setPositionText(String positionText) {
            this.positionText = positionText;
        }
    }

@JsonProperty annotation on field as well as getter/setter

My observations based on a few tests has been that whichever name differs from the property name is one which takes effect:

For eg. consider a slight modification of your case:

@JsonProperty("fileName")
private String fileName;

@JsonProperty("fileName")
public String getFileName()
{
    return fileName;
}

@JsonProperty("fileName1")
public void setFileName(String fileName)
{
    this.fileName = fileName;
}

Both fileName field, and method getFileName, have the correct property name of fileName and setFileName has a different one fileName1, in this case Jackson will look for a fileName1 attribute in json at the point of deserialization and will create a attribute called fileName1 at the point of serialization.

Now, coming to your case, where all the three @JsonProperty differ from the default propertyname of fileName, it would just pick one of them as the attribute(FILENAME), and had any on of the three differed, it would have thrown an exception:

java.lang.IllegalStateException: Conflicting property name definitions

Usage of Jackson @JsonProperty annotation for kotlin data classes

@JsonProperty annotations in your code are all put on private fields within your data class and by default Jackson doesn't scan private fields for annotations. You have to instruct it to do otherwise by putting @JsonAutoDetect annotation:

@JsonAutoDetect(fieldVisibility = Visibility.ANY)
data class CurrencyInfo(
    @JsonProperty("currency_info") var currencyInfo: CurrencyInfoItem?
)

or alternatively you can move your annotations on accessor methods:

data class CurrencyInfo(
    @get:JsonProperty("currency_info") var currencyInfo: CurrencyInfoItem?
)

@JsonProperty annotation is getting ignored in mongodb collection

In MongoDB you're saving an object with his properties names.
JsonProperty annotation mapping the deserialization and the serialization with given object.

Marker annotation that can be used to define a non-static method as a
"setter" or "getter" for a logical property (depending on its
signature), or non-static object field to be used (serialized,
deserialized) as a logical property. Default value ("") indicates that
the field name is used as the property name without any modifications,
but it can be specified to non-empty value to specify different name.
Property name refers to name used externally, as the field name in
JSON objects.

https://fasterxml.github.io/jackson-annotations/javadoc/2.8/com/fasterxml/jackson/annotation/JsonProperty.html

By using @Field property annotation you can save property in different name as in object.

---

Related Topics