Can not deserialize json to enum value with Object-/Array-valued input, @JsonCreator

[peteryuanpan]

Describe the bug
can not deserialize json to enum value in a particular case

Version information
Which Jackson version(s) was this for?
2.11.0

To Reproduce
If you have a way to reproduce this with:

1. Brief code sample/snippet: include here in preformatted/code section

package server.test202109;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fenbi.common.util.IgnorableObjectMapper;

import java.io.IOException;

/**
 * @author peteryuanpan
 */
public class TestJackSon {

    private static final String json1 = "{\"b\":\"x\"}";
    private static final String json2 = "{\"a\":\"1\", \"b\":\"x\"}";
    private static final String json3 = "{\"a\":[], \"b\":\"x\"}";
    private static final String json4 = "{\"a\":{}, \"b\":\"x\"}";
    private static final String json5 = "{\"b\":\"x\", \"a\":[]}";
    private static final String json6 = "{\"b\":\"y\", \"a\":{}}";

    private static final IgnorableObjectMapper objectMapper = new IgnorableObjectMapper();

    public static void main(String[] args) throws IOException {
        test(json1);
        test(json2);
        test(json3);
        test(json4);
        test(json5);
        test(json6);
    }

    private static void test(String json) throws IOException {
        Enum e = objectMapper.readValue(json, Enum.class);
        System.out.println(e == null);
    }

    enum Enum {
        x("x"),
        y("y"),
        z("z");
        private final String value;
        Enum(String value) {
            this.value = value;
        }
        @JsonCreator
        public static Enum getByValue(@JsonProperty("b") String value) {
            for (Enum e : Enum.values()) {
                if (e.value.equals(value)) {
                    return e;
                }
            }
            return null;
        }
    }
}

2. Longer example stored somewhere else (diff repo, snippet), add a link
3. Textual explanation: include here
   The output is

false
false
true
true
false
false

can not deserialize json3 and json4, because there is "]" or "}" before the parameter "b"

Expected behavior
all output is false

Additional context
Add any other context about the problem here.

[peteryuanpan]

I have read a little source code, please let me note down here

com.fasterxml.jackson.databind.deser.impl.PropertyValueBuffer

    public Object[] getParameters(SettableBeanProperty[] props)
        throws JsonMappingException
    {
        // quick check to see if anything else is needed
        if (_paramsNeeded > 0) {
            if (_paramsSeenBig == null) {
                int mask = _paramsSeen;
                // not optimal, could use `Integer.trailingZeroes()`, but for now should not
                // really matter for common cases
                for (int ix = 0, len = _creatorParameters.length; ix < len; ++ix, mask >>= 1) {
                    if ((mask & 1) == 0) {
                        _creatorParameters[ix] = _findMissing(props[ix]);
                    }
                }
            } else {
                final int len = _creatorParameters.length;
                for (int ix = 0; (ix = _paramsSeenBig.nextClearBit(ix)) < len; ++ix) {
                    _creatorParameters[ix] = _findMissing(props[ix]);
                }
            }
        }

        if (_context.isEnabled(DeserializationFeature.FAIL_ON_NULL_CREATOR_PROPERTIES)) {
            for (int ix = 0; ix < props.length; ++ix) {
                if (_creatorParameters[ix] == null) {
                    SettableBeanProperty prop = props[ix];
                    _context.reportInputMismatch(prop,
                            "Null value for creator property '%s' (index %d); `DeserializationFeature.FAIL_ON_NULL_FOR_CREATOR_PARAMETERS` enabled",
                            prop.getName(), props[ix].getCreatorIndex());
                }
            }
        }
        return _creatorParameters;
    }

    public boolean assignParameter(SettableBeanProperty prop, Object value)
    {
        final int ix = prop.getCreatorIndex();
        _creatorParameters[ix] = value;
        if (_paramsSeenBig == null) {
            int old = _paramsSeen;
            int newValue = (old | (1 << ix));
            if (old != newValue) {
                _paramsSeen = newValue;
                if (--_paramsNeeded <= 0) {
                    // 29-Nov-2016, tatu: But! May still require Object Id value
                    return (_objectIdReader == null) || (_idValue != null);
                }
            }
        } else {
            if (!_paramsSeenBig.get(ix)) {
                _paramsSeenBig.set(ix);
                if (--_paramsNeeded <= 0) {
                    // 29-Nov-2016, tatu: But! May still require Object Id value
                }
            }
        }
        return false;
    }

com.fasterxml.jackson.databind.deser.std.FactoryBasedEnumDeserializer

    // Method to deserialize the Enum using property based methodology
    protected Object deserializeEnumUsingPropertyBased(final JsonParser p, final DeserializationContext ctxt,
    		final PropertyBasedCreator creator) throws IOException
    {
        PropertyValueBuffer buffer = creator.startBuilding(p, ctxt, null);
    
        JsonToken t = p.currentToken();
        for (; t == JsonToken.FIELD_NAME; t = p.nextToken()) {
            String propName = p.getCurrentName();
            p.nextToken(); // to point to value
    
            SettableBeanProperty creatorProp = creator.findCreatorProperty(propName);
            if (creatorProp != null) {
                buffer.assignParameter(creatorProp, _deserializeWithErrorWrapping(p, ctxt, creatorProp));
                continue;
            }
            if (buffer.readIdProperty(propName)) {
                continue;
            }
        }
        return creator.build(ctxt, buffer);
    }

com.fasterxml.jackson.core.json.ReaderBasedJsonParser

    @Override
    public final JsonToken nextToken() throws IOException
    {
        /* First: field names are special -- we will always tokenize
         * (part of) value along with field name to simplify
         * state handling. If so, can and need to use secondary token:
         */
        if (_currToken == JsonToken.FIELD_NAME) {
            return _nextAfterName();
        }
        // But if we didn't already have a name, and (partially?) decode number,
        // need to ensure no numeric information is leaked
        _numTypesValid = NR_UNKNOWN;
        if (_tokenIncomplete) {
            _skipString(); // only strings can be partial
        }
        int i = _skipWSOrEnd();
        if (i < 0) { // end-of-input
            // Should actually close/release things
            // like input source, symbol table and recyclable buffers now.
            close();
            return (_currToken = null);
        }
        // clear any data retained so far
        _binaryValue = null;

        // Closing scope?
        if (i == INT_RBRACKET || i == INT_RCURLY) {
            _closeScope(i);
            return _currToken;
        }

        // Nope: do we then expect a comma?
        if (_parsingContext.expectComma()) {
            i = _skipComma(i);

            // Was that a trailing comma?
            if ((_features & FEAT_MASK_TRAILING_COMMA) != 0) {
                if ((i == INT_RBRACKET) || (i == INT_RCURLY)) {
                    _closeScope(i);
                    return _currToken;
                }
            }
        }

        /* And should we now have a name? Always true for Object contexts, since
         * the intermediate 'expect-value' state is never retained.
         */
        boolean inObject = _parsingContext.inObject();
        if (inObject) {
            // First, field name itself:
            _updateNameLocation();
            String name = (i == INT_QUOTE) ? _parseName() : _handleOddName(i);
            _parsingContext.setCurrentName(name);
            _currToken = JsonToken.FIELD_NAME;
            i = _skipColon();
        }
        _updateLocation();

        // Ok: we must have a value... what is it?

        JsonToken t;

        switch (i) {
        case '"':
            _tokenIncomplete = true;
            t = JsonToken.VALUE_STRING;
            break;
        case '[':
            if (!inObject) {
                _parsingContext = _parsingContext.createChildArrayContext(_tokenInputRow, _tokenInputCol);
            }
            t = JsonToken.START_ARRAY;
            break;
        case '{':
            if (!inObject) {
                _parsingContext = _parsingContext.createChildObjectContext(_tokenInputRow, _tokenInputCol);
            }
            t = JsonToken.START_OBJECT;
            break;
        case '}':
            // Error: } is not valid at this point; valid closers have
            // been handled earlier
            _reportUnexpectedChar(i, "expected a value");
        case 't':
            _matchTrue();
            t = JsonToken.VALUE_TRUE;
            break;
        case 'f':
            _matchFalse();
            t = JsonToken.VALUE_FALSE;
            break;
        case 'n':
            _matchNull();
            t = JsonToken.VALUE_NULL;
            break;

        case '-':
            /* Should we have separate handling for plus? Although
             * it is not allowed per se, it may be erroneously used,
             * and could be indicate by a more specific error message.
             */
            t = _parseNegNumber();
            break;
        case '.': // [core#61]]
            t = _parseFloatThatStartsWithPeriod();
            break;
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
            t = _parsePosNumber(i);
            break;
        default:
            t = _handleOddValue(i);
            break;
        }

        if (inObject) {
            _nextToken = t;
            return _currToken;
        }
        _currToken = t;
        return t;
    }

    private final int _skipWSOrEnd() throws IOException
    {
        // Let's handle first character separately since it is likely that
        // it is either non-whitespace; or we have longer run of white space
        if (_inputPtr >= _inputEnd) {
            if (!_loadMore()) {
                return _eofAsNextChar();
            }
        }
        int i = _inputBuffer[_inputPtr++];
        if (i > INT_SPACE) {
            if (i == INT_SLASH || i == INT_HASH) {
                --_inputPtr;
                return _skipWSOrEnd2();
            }
            return i;
        }
        if (i != INT_SPACE) {
            if (i == INT_LF) {
                ++_currInputRow;
                _currInputRowStart = _inputPtr;
            } else if (i == INT_CR) {
                _skipCR();
            } else if (i != INT_TAB) {
                _throwInvalidSpace(i);
            }
        }

        while (_inputPtr < _inputEnd) {
            i = (int) _inputBuffer[_inputPtr++];
            if (i > INT_SPACE) {
                if (i == INT_SLASH || i == INT_HASH) {
                    --_inputPtr;
                    return _skipWSOrEnd2();
                }
                return i;
            }
            if (i != INT_SPACE) {
                if (i == INT_LF) {
                    ++_currInputRow;
                    _currInputRowStart = _inputPtr;
                } else if (i == INT_CR) {
                    _skipCR();
                } else if (i != INT_TAB) {
                    _throwInvalidSpace(i);
                }
            }
        }
        return _skipWSOrEnd2();
    }

    private void _closeScope(int i) throws JsonParseException {
        if (i == INT_RBRACKET) {
            _updateLocation();
            if (!_parsingContext.inArray()) {
                _reportMismatchedEndMarker(i, '}');
            }
            _parsingContext = _parsingContext.clearAndGetParent();
            _currToken = JsonToken.END_ARRAY;
        }
        if (i == INT_RCURLY) {
            _updateLocation();
            if (!_parsingContext.inObject()) {
                _reportMismatchedEndMarker(i, ']');
            }
            _parsingContext = _parsingContext.clearAndGetParent();
            _currToken = JsonToken.END_OBJECT;
        }
    }

[cowtowncoder]

Hi @peteryuanpan! Thank you for reporting this, I will have a look.

[cowtowncoder]

Ok, looks like what was missing is the skipping of content for structured values (Object, Array) -- they consist of more than one token. So needed to add:

p.skipChildren();

within deserializeEnumUsingPropertyBased() of FactoryBasedEnumDeserializer.

Fix will be in 2.13.0; I merged it in 2.12 but not sure if there will be new patch releases from there.