My controller is annotated as
public ModelAndView execute(final HttpServletRequest request, #ModelAttribute final UploadFormBean uploadFormBean) {
//some code.
Type t = uploadFormBean.getType(); //t is null.
//some more code.
}
The UploadFormBean is defined as:
public class UploadFormBean {
private Type type;
public enum Type {
A ("abc"),
B ("xyz"),
C ("pqr");
private final String str;
private Type(final String str) {
this.str = str;
}
#Override
public String toString() {
return str;
}
}
public Type getType() {
return type;
}
public void setType(final String type) {
for (Type s: Type.values()) {
if (s.toString().equalsIgnoreCase(type)) {
this.type = s;
}
}
}
}
Why is #mMdelAttribute not able to set type variable (t is null in execute function)?
What am I missing? Also, please explain how does #ModelAttribute binds the data members from http request to a java bean.
Note: this works fine in case when type is a String and setType is defined as:
void setType(final String type) {
this.type = type;
}
JSP:
<input type="hidden" name="type" value="abc">
<input type="hidden" name="type" value="xyz">
1)Why is #mMdelAttribute not able to set type variable (t is null in execute function)?
Because for binding it will expect a setter like like one below.
public void setType(final Type type) {
this.type = type) ;
}
But this wont work as path value in spring form,because enum will not have
public constructor.
So better way to achieve this is to re factor your bean like one below
public class UploadFormBean {
private String type;
public enum Type {
A ("abc"),
B ("xyz"),
C ("pqr");
private final String str;
private Type(final String str) {
this.str = str;
}
#Override
public String toString() {
return str;
}
}
public String getType() {
return type;
}
public void setType(String type) {
for (Type s: Type.values()) {
if (s.toString().equalsIgnoreCase(type)) {
this.type = s.name();
}
}
}
}
Related
Room is not finding setType method defined in the parent class. Gives cannot find setter for field error during compilation.
Parent class
public class Data {
private int type = -1;
public Data() {
}
public int getType() {
return type;
}
public Data setType(int type) {
this.type = type;
return this;
}
}
Child class
#Entity
public class Log extends Data {
#PrimaryKey(autoGenerate = true)
public int id;
public Log() {
}
}
Usually setters do not return values.
Change your setType() method to:
public void setType(int type) {
this.type = type;
}
P.S. Obviously, returning the same instance of Data object is useless here, since you're invoking the method on that object and already have it.
If you want to keep the builder pattern, you could consider using an internal static class for that matter as follows (you don't need an empty constructor, that's added implicitly):
public class Data {
private int type = -1;
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
public static class Builder {
private Data data = new Data();
public Builder setType(int type) {
data.setType(type);
return this;
}
public Data build() {
return data;
}
}
}
Now, for creating a data class you could do:
Data data = new Data.Builder()
.setType(10)
.build();
I have a base class (Foo) with 2 children (A and B). They look like this:
public abstract class Foo {
private String fooString;
public Foo(String fooString) {
this.fooString = fooString;
}
//getter
}
#JsonDeserialize(builder = A.ABuilder.class)
public class A extends Foo {
private int amount;
public A(String fooString, int amount) {
super(fooString);
this.amount = amount;
}
//getter
#JsonPOJOBuilder
public static class ABuilder {
private String fooString;
private int amount;
public ABuilder withFooString(final String fooString) {
this.fooString = fooString;
return this;
}
public ABuilder withAmount(final int amount) {
this.amount = amount;
return this;
}
public A build() {
return new A(fooString, amount);
}
}
}
#JsonDeserialize(builder = B.BBuilder.class)
public class B extends Foo {
private String type;
public B(String fooString, String type) {
super(fooString);
this.type = type;
}
//getter
#JsonPOJOBuilder
public static class BBuilder {
private String fooString;
private String type;
public BBuilder withFooString(final String fooString) {
this.fooString = fooString;
return this;
}
public BBuilder withType(final String type) {
this.type = type;
return this;
}
public B build() {
return new B(fooString, type);
}
}
}
In my controller I have this endpoint:
#PutMapping
private ResponseEntity<Foo> doSomething(#RequestBody Foo dto) {
//stuff
}
But whenever I try to send over my json payload:
{
"fooString":"test",
"amount":1
}
I get the error:
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.test.Foo` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
at [Source: (String)"{"fooString":"test","amount":1}; line: 1, column: 1]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1451)
at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1027)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:265)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3004)
at AbstractJackson.main(AbstractJackson.java:11)
How do I get jackson to deserialize the json into the proper child class? What am I doing wrong?
The base class won't get the constructors of the sub classes instead it is quite the opposite,you cannot set subclass specific properties in base class instead you need to use specific subclass for the call or use custom deserializer for base class with correct use intanceOf
The easiest way to get it working is to change the controller method.
#PutMapping
private ResponseEntity<Foo> doSomething(#RequestBody A dto) {
//stuff
}
I have no idea what to do with this problem.
I have a JSON object to assist in value input through POST (using Play Framework) that structures like this:
{
"start_absolute": 1403185486254,
"end_absolute": 1403185486254,
"metrics": [
{
"name": "parts",
"tags": [
{
"key":"machine",
"value":"10"
}
],
"sampling":
{
"value": 1,
"unit": "minutes"
}
}
]
}
And in server side i try to process the info like this:
Form<QueryForm> queryForm = Form.form(QueryForm.class).bindFromRequest();
if (queryForm.hasErrors()) {
return badRequest(queryForm.errorsAsJson());
}
QueryForm queryInfo = queryForm.get();
the classes used to define the JSON object in java
public class QueryForm {
private Date start_absolute;
private Date end_absolute;
private List<MetricForm> metrics= Lists.newArrayList();
public Date getStart_absolute() {
return start_absolute;
}
public void setStart_absolute(long start_absolute) {
this.start_absolute = new Date(start_absolute);
}
public Date getEnd_absolute() {
return end_absolute;
}
public void setEnd_absolute(long end_absolute) {
this.end_absolute =new Date(end_absolute);
}
public List<MetricForm> getMetrics() {
return metrics;
}
public void setMetrics(List<MetricForm> metrics) {
this.metrics = metrics;
}
#Override
public String toString() {
return "QueryForm[start_absolute="+start_absolute+", end_absolute="+end_absolute+", metrics="+metrics+"]";
}
.
public class MetricForm {
private String name;
private List<Tag> tags= Lists.newArrayList();
private RelativeTimeForm sampling= new RelativeTimeForm(1,"milliseconds");
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Tag> getTags() {
return tags;
}
public void setTags(List<Tag> tags) {
this.tags.addAll(tags);
}
public RelativeTimeForm getSampling() {
return sampling;
}
public void setSampling(int val, String unit) {
this.sampling.setUnit(unit);
this.sampling.setVal(val);
}
#Override
public String toString() {
return "MetricForm[name="+name+", tags="+tags+",sampling="+sampling+"]";
}
.
public class Tag {
private String key;
private String value;
public Tag(String key, String value) {
this.key = key;
this.value = value;
}
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
#Override
public String toString() {
return String.format(
"Tag[key=%s, value='%s']",
key, value
);
}
}
.
public class RelativeTimeForm {
private int value;
private String unit;
public RelativeTimeForm (int val, String unit){
this.setValue(val);
this.setUnit(unit);
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public String getUnit() {
return unit;
}
public void setUnit(String unit) {
this.unit = unit;
}
#Override
public String toString() {
return "RelativeTimeForm[value="+value+", unit="+unit+"]";
}
I'm not experienced working with play.data.Form but in previous ocasions with simpler objects (Using primitive data types and String) this worked fine but when i tried to POST to the play application (Header: Content-Type = application/json; charset=utf-8) it occurs an Internal Server Error:
play.api.Application$$anon$1: Execution exception [[InvalidPropertyException:
Invalid property 'metrics[0].tags[0]' of bean class [model.QueryForm]: Illegal
attempt to get property 'tags' threw exception; nested exception is
org.springframework.beans.NullValueInNestedPathException: Invalid property
'metrics[0].tags' of bean class [model.QueryForm]: Could not instatiate property
path:
java.lang:InstatiationException: [model.Tag]
Any one can help with this? I can´t figure out what to do. Is it to complex of an object to convert from JSON? Do i need to add some JSON Annotations (not currently using them)?
I have no clue how to fix this
UPDATE: I narrowed it down to the Tag class. for some reason i'm not able to instatiate Tag through JSON. I even tried setting a single Tag instance in the same level as the dates and it gives the same error (It work for Sampling)
RESOLVED:
Spring binding exception when a form is submitted
The answer is in the post above. I have to set an empty construtor in Tag class for it to work.
public Tag(){
}
The exception means, that one or more attributes aren't instantiated.
private List<MetricForm> metrics = new ...;
private List<Tag> tags = new ...;
private RelativeTimeForm sampling = new ...;
should do it.
In the case you get problems to read in your time values: Instead of using Date type directly to read in, I would use long to read in the time values and then (internally) convert them to Date objects.
I've faced with a requirement to deserialize fields that possibly can be transient using XStream 1.4.2. Despite of that, such fields may be annotated with both #XStreamAlias and #XStreamAsAttribute. Yes, I know, it sounds weird, and this is an indicator of bad design, but this is what I currently have. Since XStream offers a way to specify custom converter, I tried to extend com.thoughtworks.xstream.converters.reflection.ReflectionConverter in order to override the default way of omitting all transient fields trying to make XStream allow to deserialize them. However, I've fully stuck having two ideas to implement such a converter, but none of them works. So here is what I tried:
The 1st way doesn't work:
public final class TransientSimpleConverter extends ReflectionConverter {
private final Class<?> type;
private TransientSimpleConverter(Class<?> type, Mapper mapper, ReflectionProvider reflectionProvider) {
super(mapper, reflectionProvider);
this.type = type;
}
public static TransientSimpleConverter transientSimpleConverter(Class<?> type, XStream xStream) {
return new TransientSimpleConverter(type, xStream.getMapper(), xStream.getReflectionProvider());
}
#Override
protected boolean shouldUnmarshalTransientFields() {
return true;
}
#Override
public boolean canConvert(Class type) {
return this.type == type;
}
}
The 2nd way doesn't work either:
public final class TransientComplexConverter extends ReflectionConverter {
private final Class<?> type;
private TransientComplexConverter(Class<?> type, Mapper mapper, ReflectionProvider provider) {
super(mapper, provider);
this.type = type;
}
public static TransientComplexConverter transientComplexConverter(Class<?> type, Mapper mapper, Iterable<String> fieldNames) {
return new TransientComplexConverter(type, mapper, TransientHackReflectionProvider.transientHackReflectionProvider(type, fieldNames));
}
#Override
public boolean canConvert(Class type) {
return this.type == type;
}
private static final class TransientHackReflectionProvider extends PureJavaReflectionProvider {
private final Class<?> type;
private final Collection<Field> allowedFields;
private final Collection<String> allowedAliases;
private TransientHackReflectionProvider(Class<?> type, Collection<Field> allowedFields, Collection<String> allowedAliases) {
this.type = type;
this.allowedFields = allowedFields;
this.allowedAliases = allowedAliases;
}
public static TransientHackReflectionProvider transientHackReflectionProvider(final Class<?> type, Iterable<String> fieldNames) {
final Collection<Field> allowedFields = from(fieldNames).transform(new Function<String, Field>() {
#Override
public Field apply(String name) {
return field(type, name);
}
}).toList();
final Collection<String> allowedAliases = transform(allowedFields, new Function<Field, String>() {
#Override
public String apply(Field f) {
return f.getName();
}
});
return new TransientHackReflectionProvider(type, allowedFields, allowedAliases);
}
#Override
protected boolean fieldModifiersSupported(Field field) {
return allowedFields.contains(field) ? true : super.fieldModifiersSupported(field);
}
#Override
public boolean fieldDefinedInClass(String fieldName, Class type) {
return type == this.type && allowedAliases.contains(fieldName) ? true : super.fieldDefinedInClass(fieldName, type);
}
private static final Field field(Class<?> type, String name) {
try {
final Field field = type.getDeclaredField(name);
checkArgument(isTransient(field.getModifiers()), name + " is not transient");
checkArgument(field.getAnnotation(XStreamAsAttribute.class) != null, name + " must be annotated with XStreamAsAttribute");
checkArgument(field.getAnnotation(XStreamAlias.class) != null, name + " must be annotated with XStreamAlias");
return field;
} catch (final SecurityException ex) {
throw new RuntimeException(ex);
} catch (final NoSuchFieldException ex) {
throw new RuntimeException(ex);
}
}
}
}
Any suggestions or ideas for a workaround? Thanks in advance.
I know this post is old, but maybe someone is still interested. My solution:
XStream xstream = new XStream(new MyPureJavaReflectionProvider());
class MyPureJavaReflectionProvider extends PureJavaReflectionProvider {
public MyPureJavaReflectionProvider() {
this(new FieldDictionary(new ImmutableFieldKeySorter()));
}
public MyPureJavaReflectionProvider(FieldDictionary fieldDictionary) {
super(fieldDictionary);
}
protected boolean fieldModifiersSupported(Field field) {
int modifiers = field.getModifiers();
return !Modifier.isStatic(modifiers);
}
public boolean fieldDefinedInClass(String fieldName, Class type) {
Field field = fieldDictionary.fieldOrNull(type, fieldName, null);
return field != null && fieldModifiersSupported(field);
}
}
I'm working with Mule Studio in this, and I actually was wondering the possibility to add the drop down list with a "custom" string name. The case applies for MIME Types (ContentTypes) names. (i.e: text/css, text/javascript, and so)
Made an structure like this:
public enum HttpContentType {
TEXT_PLAIN
{
public String toString() {
return "text/plain";
}
},
TEXT_CSS
{
public String toString() {
return "text/css";
}
},
TEXT_JS
{
public String toString() {
return "text/javascript";
}
},
TEXT_XML
{
public String toString() {
return "text/xml";
}
},
};
To then be used like this as a Configurable attribute:
/**
* Connection Content Types
*/
#Configurable
#Placement(order=1,group="Configuration",tab="HTTP Configuration")
private HttpContentType contentType;
But of course that when reading that from the Mule Studio it will be a Drop Down list with names such as: TEXT_CSS, TEXT_XML, TEXT_JAVASCRIPT ( http://puu.sh/3vLbd.png ) and so instead of text/css, text/xml, text/javascript.
How can i achieve this result?
A far better way to achieve this would be to provide a field in your enum, and provide an appropriate constructor:
public enum HttpContentType {
TEXT_PLAIN("text/plain"),
TEXT_CSS("text/css");
private String value;
HttpContentType(String value) {
this.value = value;
}
public String toString() {
return this.value;
}
public static HttpContentType getByValue(String value){
for (final HttpContentType element : EnumSet.allOf(HttpContentType.class)) {
if (element.toString().equals(value)) {
return element;
}
}
return null;
}
}
One option is to provide a different method to get the MIME string.
public interface IMimeTypeProvider {
public String toMimeType();
}
public enum HttpContentType implements IMimeTypeProvider {
TEXT_PLAIN
{
public String toMimeType() {
return "text/plain";
}
},
...
public String toMimeType() {
return "text/plain";
}
}
You might also consider adding a toDisplayString() method. The enumerator name is not necessarily a good display name, even in a single locale.
public enum HttpContentType {
TEXT_PLAIN("text/plain"), TEXT_CSS("text/css");
private String code;
HttpContentType(String code) {
this.code = code;
}
public String toString() {
return code;
}
public static HttpContentType getEnum(String code) {
if (code.equals("text/plain")) {
return TEXT_PLAIN;
} else if (code.equals("text/css")) {
return TEXT_CSS;
} else {
return null;
}
}
}