Create @LogIgnore as Complement to @JsonIgnore

[vjkoskela]

Create an additional annotation @LogIgnore and associated filter to augment @JsonIgnore for logging. Additionally, the configuration for @LogIgnore should allow disabling of @JsonIgnore (e.g. to ignore @JsonIgnore).

This is similar to the relationship between @LogValue and @JsonValue. The pattern allows developers to create a distinct serialization profile of a class for logging and another one for standard serialization/deserialization. It is particularly important when the existing serialization profile already exists and logging is being migrated to Logback-Steno.

Disabling @JsonIgnore and using @LogIgnore instead would accomplish at least part of this. We will still need to investigate how to support customized serialization and the annotations that come with it.

See: FasterXML/jackson-databind#133

Reference implementation of annotation:

package com.arpnetworking.logback.annotations;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
* Annotation that marks a field to be ignored by the RedactionFilter in StenoEncoder.
*
* @author Ville Koskela (vkoskela at groupon dot com)
* @see com.arpnetworking.logback.jackson.RedactionFilter
* @since 1.9.0
*/
@Target( { ElementType.METHOD, ElementType.FIELD } )
@Retention(RetentionPolicy.RUNTIME)
public @interface LogIgnore {
}

Reference implementation of filter:

package com.arpnetworking.logback.jackson;
import java.util.Collections;
import java.util.Set;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.BeanPropertyWriter;
import com.fasterxml.jackson.databind.ser.PropertyWriter;
import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter;
import com.arpnetworking.logback.annotations.LogIgnore;

/**
 * Jackson property filter that suppresses fields annotated with @LogIgnore.
 *
 * @author Ville Koskela (vkoskela at groupon dot com)
 * @since 1.9.0
 */
public class IgnoreFilter extends SimpleBeanPropertyFilter.SerializeExceptFilter {
    private static final long serialVersionUID = -8732095428853471218L;
    public static final String IGNORE_FILTER_ID = "com.arpnetworking.logback.jackson.IgnoreFilterId";

    public IgnoreFilter() { 
        this(Collections.<String>emptySet()); 
    }

    public IgnoreFilter(final Set<String> properties) { 
        super(properties); 
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @Deprecated
    public void serializeAsField(
            final Object pojo,
            final JsonGenerator jgen,
            final SerializerProvider prov,
            final BeanPropertyWriter writer) throws Exception {
        if (writer.getAnnotation(LogIgnore.class) == null) { 
            super.serializeAsField(pojo, jgen, prov, writer); 
        }
        // else: ignore field entirely
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void serializeAsField(
            final Object pojo,
            final JsonGenerator jgen,
            final SerializerProvider prov,
            final PropertyWriter writer) throws Exception {
        if (writer instanceof BeanPropertyWriter) { 
                final BeanPropertyWriter beanPropertyWriter = (BeanPropertyWriter) writer; 
                if (beanPropertyWriter.getAnnotation(LogIgnore.class) == null) { 
                    super.serializeAsField(pojo, jgen, prov, writer); 
                } 
                // else
        } else { 
            super.serializeAsField(pojo, jgen, prov, writer); 
        }
    }
}