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Allow TokenFilter to preserve empty (#729)
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This creates two new method on `TokenFilter` which you can override to
decide if empty arrays and objects should be included or excluded. 

Closes #715
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@nik9000
nik9000 committed Jan 3, 2022
1 parent e302dd8 commit 8bed4d8
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Showing 6 changed files with 454 additions and 5 deletions.
64 changes: 60 additions & 4 deletions src/main/java/com/fasterxml/jackson/core/filter/FilteringParserDelegate.java
View file
Expand Up @@ -273,16 +273,22 @@ public JsonToken nextToken() throws IOException
_exposedContext = null;
if (ctxt.inArray()) {
t = delegate.getCurrentToken();
// Is this guaranteed to work without further checks?
// if (t != JsonToken.START_ARRAY) {
_currToken = t;
if (_currToken == JsonToken.END_ARRAY) {
_headContext = _headContext.getParent();
_itemFilter = _headContext.getFilter();
}
return t;
}

// 19-Jul-2021, tatu: [core#700]: following was commented out?!
// Almost! Most likely still have the current token;
// with the sole exception of FIELD_NAME
t = delegate.currentToken();
if (t == JsonToken.END_OBJECT) {
_headContext = _headContext.getParent();
_itemFilter = _headContext.getFilter();
}
if (t != JsonToken.FIELD_NAME) {
_currToken = t;
return t;
Expand Down Expand Up @@ -562,12 +568,15 @@ protected final JsonToken _nextToken2() throws IOException
continue main_loop;

case ID_END_ARRAY:
case ID_END_OBJECT:
{
boolean returnEnd = _headContext.isStartHandled();
f = _headContext.getFilter();
if ((f != null) && (f != TokenFilter.INCLUDE_ALL)) {
boolean includeEmpty = f.includeEmptyArray(_headContext.hasCurrentIndex());
f.filterFinishArray();
if (includeEmpty) {
return _nextBuffered(_headContext);
}
}
_headContext = _headContext.getParent();
_itemFilter = _headContext.getFilter();
Expand All @@ -576,6 +585,23 @@ protected final JsonToken _nextToken2() throws IOException
}
}
continue main_loop;
case ID_END_OBJECT:
{
boolean returnEnd = _headContext.isStartHandled();
f = _headContext.getFilter();
if ((f != null) && (f != TokenFilter.INCLUDE_ALL)) {
boolean includeEmpty = f.includeEmptyArray(_headContext.hasCurrentName());
f.filterFinishObject();
if (includeEmpty) {
return _nextBuffered(_headContext);
} }
_headContext = _headContext.getParent();
_itemFilter = _headContext.getFilter();
if (returnEnd) {
return (_currToken = t);
}
}
continue main_loop;

case ID_FIELD_NAME:
{
Expand Down Expand Up @@ -708,13 +734,16 @@ protected final JsonToken _nextTokenWithBuffering(final TokenFilterContext buffR
continue main_loop;

case ID_END_ARRAY:
case ID_END_OBJECT:
{
// Unlike with other loops, here we know that content was NOT
// included (won't get this far otherwise)
f = _headContext.getFilter();
if ((f != null) && (f != TokenFilter.INCLUDE_ALL)) {
boolean includeEmpty = f.includeEmptyArray(_headContext.hasCurrentIndex());
f.filterFinishArray();
if (includeEmpty) {
return _nextBuffered(buffRoot);
}
}
boolean gotEnd = (_headContext == buffRoot);
boolean returnEnd = gotEnd && _headContext.isStartHandled();
Expand All @@ -727,6 +756,33 @@ protected final JsonToken _nextTokenWithBuffering(final TokenFilterContext buffR
}
}
continue main_loop;
case ID_END_OBJECT:
{
// Unlike with other loops, here we know that content was NOT
// included (won't get this far otherwise)
f = _headContext.getFilter();
if ((f != null) && (f != TokenFilter.INCLUDE_ALL)) {
boolean includeEmpty = f.includeEmptyObject(_headContext.hasCurrentName());
f.filterFinishObject();
if (includeEmpty) {
_headContext._currentName = _headContext._parent == null
? null
: _headContext._parent._currentName;
_headContext._needToHandleName = false;
return _nextBuffered(buffRoot);
}
}
boolean gotEnd = (_headContext == buffRoot);
boolean returnEnd = gotEnd && _headContext.isStartHandled();

_headContext = _headContext.getParent();
_itemFilter = _headContext.getFilter();

if (returnEnd) {
return t;
}
}
continue main_loop;

case ID_FIELD_NAME:
{
Expand Down
8 changes: 8 additions & 0 deletions src/main/java/com/fasterxml/jackson/core/filter/TokenFilter.java
View file
Expand Up @@ -432,6 +432,14 @@ public boolean includeEmbeddedValue(Object value) {
return _includeScalar();
}

public boolean includeEmptyArray(boolean contentsFiltered) {
return false;
}

public boolean includeEmptyObject(boolean contentsFiltered) {
return false;
}

/*
/**********************************************************
/* Overrides
Expand Down
20 changes: 20 additions & 0 deletions src/main/java/com/fasterxml/jackson/core/filter/TokenFilterContext.java
View file
Expand Up @@ -233,6 +233,16 @@ public TokenFilterContext closeArray(JsonGenerator gen) throws IOException
{
if (_startHandled) {
gen.writeEndArray();
} else {
if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
if (_filter.includeEmptyArray(hasCurrentIndex())) {
if (_parent != null) {
_parent._writePath(gen);
}
gen.writeStartArray();
gen.writeEndArray();
}
}
}
if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
_filter.filterFinishArray();
Expand All @@ -244,6 +254,16 @@ public TokenFilterContext closeObject(JsonGenerator gen) throws IOException
{
if (_startHandled) {
gen.writeEndObject();
} else {
if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
if (_filter.includeEmptyObject(hasCurrentName())) {
if (_parent != null) {
_parent._writePath(gen);
}
gen.writeStartObject();
gen.writeEndObject();
}
}
}
if ((_filter != null) && (_filter != TokenFilter.INCLUDE_ALL)) {
_filter.filterFinishObject();
Expand Down
6 changes: 5 additions & 1 deletion src/test/java/com/fasterxml/jackson/core/BaseTest.java
View file
Expand Up @@ -451,11 +451,15 @@ protected String readAndWrite(JsonFactory f, JsonParser p) throws IOException
g.disable(JsonGenerator.Feature.AUTO_CLOSE_JSON_CONTENT);
try {
while (p.nextToken() != null) {
System.err.println(p.currentToken() + " " + p.currentName() + " " + p.currentValue());
g.copyCurrentEvent(p);
}
} catch (IOException e) {
g.flush();
fail("Unexpected problem during `readAndWrite`. Output so far: '"+sw+"'; problem: "+e);
throw new AssertionError(
"Unexpected problem during `readAndWrite`. Output so far: '" +
sw + "'; problem: " + e.getMessage(),
e);
}
p.close();
g.close();
Expand Down

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