I'm using a HeaderColumnNameMappingStrategy to map a csv file with a header into a JavaBean. String values parse fine but any "true" or "false" value in csv doesn't map to JavaBean and I get the following exception from the PropertyDescriptor:
java.lang.IllegalArgumentException: argument type mismatch
The code where it occurs is in CsvToBean, line 64:
protected T processLine(MappingStrategy<T> mapper, String[] line) throws
IllegalAccessException, InvocationTargetException, InstantiationException, IntrospectionException {
T bean = mapper.createBean();
for(int col = 0; col < line.length; col++) {
String value = line[col];
PropertyDescriptor prop = mapper.findDescriptor(col);
if (null != prop) {
Object obj = convertValue(value, prop);
// this is where exception is thrown for a "true" value in csv
prop.getWriteMethod().invoke(bean, new Object[] {obj});
}
}
return bean;
}
protected PropertyEditor getPropertyEditor(PropertyDescriptor desc) throws
InstantiationException, IllegalAccessException {
Class<?> cls = desc.getPropertyEditorClass();
if (null != cls) return (PropertyEditor) cls.newInstance();
return getPropertyEditorValue(desc.getPropertyType());
}
I can confirm (via debugger) that the setter method id correctly retrieved at this point.
The problem occurs in desc.getPropertyEditorClass() since it returns null. I assumed primitive types and its wrappers are supported. Are they not?
I've run into this same issue. The cleanest way is probably to override getPropertyEditor like pritam did above and return a custom PropertyEditor for your particular object. The quick and dirty way would be to override convertValue in anonymous class form, like this:
CsvToBean<MyClass> csvToBean = new CsvToBean<MyClass>(){
#Override
protected Object convertValue(String value, PropertyDescriptor prop) throws InstantiationException,IllegalAccessException {
if (prop.getName().equals("myWhatever")) {
// return an custom object based on the incoming value
return new MyWhatever((String)value);
}
return super.convertValue(value, prop);
}
};
This is working fine for me with OpenCSV 2.3. Good luck!
I resolved this by extending CsvToBean and adding my own PropertyEditors. Turns out opencsv just supports primitive types and no wrappers.
Pritam's answer is great and this is a sample for dealing with datetime format.
PropertyEditorManager.registerEditor(java.util.Date.class, DateEditor.class);
You should write your own editor class like this:
public class DateEditor extends PropertyEditorSupport{
public static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
#Override
public void setAsText(String text){
setValue(sdf.parse(text));}
}
Related
This might be a duplicate. But I cannot find a solution to my Problem.
I have a class
public class MyResponse implements Serializable {
private boolean isSuccess;
public boolean isSuccess() {
return isSuccess;
}
public void setSuccess(boolean isSuccess) {
this.isSuccess = isSuccess;
}
}
Getters and setters are generated by Eclipse.
In another class, I set the value to true, and write it as a JSON string.
System.out.println(new ObjectMapper().writeValueAsString(myResponse));
In JSON, the key is coming as {"success": true}.
I want the key as isSuccess itself. Is Jackson using the setter method while serializing? How do I make the key the field name itself?
This is a slightly late answer, but may be useful for anyone else coming to this page.
A simple solution to changing the name that Jackson will use for when serializing to JSON is to use the #JsonProperty annotation, so your example would become:
public class MyResponse implements Serializable {
private boolean isSuccess;
#JsonProperty(value="isSuccess")
public boolean isSuccess() {
return isSuccess;
}
public void setSuccess(boolean isSuccess) {
this.isSuccess = isSuccess;
}
}
This would then be serialised to JSON as {"isSuccess":true}, but has the advantage of not having to modify your getter method name.
Note that in this case you could also write the annotation as #JsonProperty("isSuccess") as it only has the single value element
I recently ran into this issue and this is what I found. Jackson will inspect any class that you pass to it for getters and setters, and use those methods for serialization and deserialization. What follows "get", "is" and "set" in those methods will be used as the key for the JSON field ("isValid" for getIsValid and setIsValid).
public class JacksonExample {
private boolean isValid = false;
public boolean getIsValid() {
return isValid;
}
public void setIsValid(boolean isValid) {
this.isValid = isValid;
}
}
Similarly "isSuccess" will become "success", unless renamed to "isIsSuccess" or "getIsSuccess"
Read more here: http://www.citrine.io/blog/2015/5/20/jackson-json-processor
Using both annotations below, forces the output JSON to include is_xxx:
#get:JsonProperty("is_something")
#param:JsonProperty("is_something")
When you are using Kotlin and data classes:
data class Dto(
#get:JsonProperty("isSuccess") val isSuccess: Boolean
)
You might need to add #param:JsonProperty("isSuccess") if you are going to deserialize JSON as well.
EDIT: If you are using swagger-annotations to generate documentation, the property will be marked as readOnly when using #get:JsonProperty. In order to solve this, you can do:
#JsonAutoDetect(isGetterVisibility = JsonAutoDetect.Visibility.NONE)
data class Dto(
#field:JsonProperty(value = "isSuccess") val isSuccess: Boolean
)
You can configure your ObjectMapper as follows:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if(method.hasReturnType() && (method.getRawReturnType() == Boolean.class || method.getRawReturnType() == boolean.class)
&& method.getName().startsWith("is")) {
return method.getName();
}
return super.nameForGetterMethod(config, method, defaultName);
}
});
I didn't want to mess with some custom naming strategies, nor re-creating some accessors.
The less code, the happier I am.
This did the trick for us :
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
#JsonIgnoreProperties({"success", "deleted"}) // <- Prevents serialization duplicates
public class MyResponse {
private String id;
private #JsonProperty("isSuccess") boolean isSuccess; // <- Forces field name
private #JsonProperty("isDeleted") boolean isDeleted;
}
Building upon Utkarsh's answer..
Getter names minus get/is is used as the JSON name.
public class Example{
private String radcliffe;
public getHarryPotter(){
return radcliffe;
}
}
is stored as { "harryPotter" : "whateverYouGaveHere" }
For Deserialization, Jackson checks against both the setter and the field name.
For the Json String { "word1" : "example" }, both the below are valid.
public class Example{
private String word1;
public setword2( String pqr){
this.word1 = pqr;
}
}
public class Example2{
private String word2;
public setWord1(String pqr){
this.word2 = pqr ;
}
}
A more interesting question is which order Jackson considers for deserialization. If i try to deserialize { "word1" : "myName" } with
public class Example3{
private String word1;
private String word2;
public setWord1( String parameter){
this.word2 = parameter ;
}
}
I did not test the above case, but it would be interesting to see the values of word1 & word2 ...
Note: I used drastically different names to emphasize which fields are required to be same.
You can change primitive boolean to java.lang.Boolean (+ use #JsonPropery)
#JsonProperty("isA")
private Boolean isA = false;
public Boolean getA() {
return this.isA;
}
public void setA(Boolean a) {
this.isA = a;
}
Worked excellent for me.
If you are interested in handling 3rd party classes not under your control (like #edmundpie mentioned in a comment) then you add Mixin classes to your ObjectMapper where the property/field names should match the ones from your 3rd party class:
public class MyStack32270422 {
public static void main(String[] args) {
ObjectMapper om3rdParty = new ObjectMapper();
om3rdParty .addMixIn(My3rdPartyResponse.class, MixinMyResponse.class);
// add further mixins if required
String jsonString = om3rdParty.writeValueAsString(new My3rdPartyResponse());
System.out.println(jsonString);
}
}
class MixinMyResponse {
// add all jackson annotations here you want to be used when handling My3rdPartyResponse classes
#JsonProperty("isSuccess")
private boolean isSuccess;
}
class My3rdPartyResponse{
private boolean isSuccess = true;
// getter and setter here if desired
}
Basically you add all your Jackson annotations to your Mixin classes as if you would own the class. In my opinion quite a nice solution as you don't have to mess around with checking method names starting with "is.." and so on.
there is another method for this problem.
just define a new sub-class extends PropertyNamingStrategy and pass it to ObjectMapper instance.
here is a code snippet may be help more:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) {
String input = defaultName;
if(method.getName().startsWith("is")){
input = method.getName();
}
//copy from LowerCaseWithUnderscoresStrategy
if (input == null) return input; // garbage in, garbage out
int length = input.length();
StringBuilder result = new StringBuilder(length * 2);
int resultLength = 0;
boolean wasPrevTranslated = false;
for (int i = 0; i < length; i++)
{
char c = input.charAt(i);
if (i > 0 || c != '_') // skip first starting underscore
{
if (Character.isUpperCase(c))
{
if (!wasPrevTranslated && resultLength > 0 && result.charAt(resultLength - 1) != '_')
{
result.append('_');
resultLength++;
}
c = Character.toLowerCase(c);
wasPrevTranslated = true;
}
else
{
wasPrevTranslated = false;
}
result.append(c);
resultLength++;
}
}
return resultLength > 0 ? result.toString() : input;
}
});
The accepted answer won't work for my case.
In my case, the class is not owned by me. The problematic class comes from 3rd party dependencies, so I can't just add #JsonProperty annotation in it.
To solve it, inspired by #burak answer above, I created a custom PropertyNamingStrategy as follow:
mapper.setPropertyNamingStrategy(new PropertyNamingStrategy() {
#Override
public String nameForSetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if (method.getParameterCount() == 1 &&
(method.getRawParameterType(0) == Boolean.class || method.getRawParameterType(0) == boolean.class) &&
method.getName().startsWith("set")) {
Class<?> containingClass = method.getDeclaringClass();
String potentialFieldName = "is" + method.getName().substring(3);
try {
containingClass.getDeclaredField(potentialFieldName);
return potentialFieldName;
} catch (NoSuchFieldException e) {
// do nothing and fall through
}
}
return super.nameForSetterMethod(config, method, defaultName);
}
#Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName)
{
if(method.hasReturnType() && (method.getRawReturnType() == Boolean.class || method.getRawReturnType() == boolean.class)
&& method.getName().startsWith("is")) {
Class<?> containingClass = method.getDeclaringClass();
String potentialFieldName = method.getName();
try {
containingClass.getDeclaredField(potentialFieldName);
return potentialFieldName;
} catch (NoSuchFieldException e) {
// do nothing and fall through
}
}
return super.nameForGetterMethod(config, method, defaultName);
}
});
Basically what this does is, before serializing and deserializing, it checks in the target/source class which property name is present in the class, whether it is isEnabled or enabled property.
Based on that, the mapper will serialize and deserialize to the property name that is exist.
Normally, the .Dump() extension method in LINQPad shows XNode and its derived class instances as a rendered XML fragment. Sometimes while developing code I would prefer to see actual properties of the object, in the same table form that is dumped for other types, like a table that would show the Name, Value, FirstAttribute and whatsnot properties of the node and their .ToString() values, or interactively expandable collections of subobjects. In short, as if XNode were not handled specially at all.
I am working around this by dumping individual properties, but this is tedious.
This answer suggests writing a custom extension code to achieve a similar effect for another type, namely IEnumerable, but it seems a narrower and rarer case than that which I am dealing with.
Is there an out-of-the box way to do what I want?
LINQPad supports customizing Dump for types. Using some extension methods, you can convert the types to ExpandoObjects and then they will be output with properties.
In My Extensions, after the MyExtensions class, add a top level method:
static object ToDump(object obj) {
if (obj is XObject x)
return x.ToExpando();
else
return obj;
}
In the MyExtensions class, add the following extension methods. I already had the object->Dictionary methods for converting to anonymous objects, so I used those, but you could combine them to create a single ToExpando on object:
public static ExpandoObject ToExpando(this object obj) => obj.ToDictionary().ToExpando();
public static IDictionary<string, object> ToDictionary(this object obj) {
if (obj is IDictionary<string, object> id)
return id;
else {
var dictAnsObj = new Dictionary<string, object>();
foreach (var prop in obj.GetType().GetPropertiesOrFields()) {
try {
dictAnsObj.Add(prop.Name, prop.GetValue(obj));
}
catch (Exception ex) {
dictAnsObj.Add(prop.Name, ex);
}
}
return dictAnsObj;
}
}
public static ExpandoObject ToExpando(this IDictionary<string, object> objDict) {
var e = new ExpandoObject();
var di = (IDictionary<string, object>)e;
foreach (var kvp in objDict)
di.Add(kvp);
return e;
}
You will also need this Type extension:
// ***
// *** Type Extensions
// ***
public static List<MemberInfo> GetPropertiesOrFields(this Type t, BindingFlags bf = BindingFlags.Public | BindingFlags.Instance) =>
t.GetMembers(bf).Where(mi => mi.MemberType == MemberTypes.Field | mi.MemberType == MemberTypes.Property).ToList();
If you are okay with just displaying the top level object in class format, you could just use this extension method when you need to:
public static T DumpAs<T, NewT>(this T obj, Func<T, NewT> castFn, string description = null) {
if (description != null)
castFn(obj).Dump(description);
else
castFn(obj).Dump();
return obj;
}
For example,
XElement xn;
xn.DumpAs(x => x.ToExpando());
Otherwise, you will have to comment out the ToDump method or do something tricky with fluent methods to turn it on and off.
This answer depends on the previous answer, but extends it to handle dumping XObjects as classes when desired with an alternative extension method and ToDump method. It uses the same extensions as my previous answer otherwise.
In the MyExtensions class, add a new type of dump and a bool to track status:
public static bool bDumpAsClass = false;
public static object DumpAsClass(this object input, string descr = null) {
bDumpAsClass = true;
if (descr != null)
input.Dump(descr);
else
input.Dump();
bDumpAsClass = false;
return input;
}
Outside the MyExtensions class, add a ToDump method that uses the bool:
static object ToDump(object obj) {
if (MyExtensions.bDumpAsClass) {
if (obj is XObject x)
return x.ToExpando();
}
return obj;
}
Then you can just use DumpAsClass instead of Dump when you want to dump an XObject or descendant as a class, expanding any members as well.
Obviously you could expand the types handled when bDumpAsClass is true.
I've read this answer (How to store complex objects into hadoop Hbase?) regarding the storing of string arrays with HBase.
There it is said to use the ArrayWritable Class to serialize the array. With WritableUtils.toByteArray(Writable ... writable) I'll get a byte[] which I can store in HBase.
When I now try to retrieve the rows again, I get a byte[] which I have somehow to transform back again into an ArrayWritable.
But I don't find a way to do this. Maybe you know an answer or am I doing fundamentally wrong serializing my String[]?
You may apply the following method to get back the ArrayWritable (taken from my earlier answer, see here) .
public static <T extends Writable> T asWritable(byte[] bytes, Class<T> clazz)
throws IOException {
T result = null;
DataInputStream dataIn = null;
try {
result = clazz.newInstance();
ByteArrayInputStream in = new ByteArrayInputStream(bytes);
dataIn = new DataInputStream(in);
result.readFields(dataIn);
}
catch (InstantiationException e) {
// should not happen
assert false;
}
catch (IllegalAccessException e) {
// should not happen
assert false;
}
finally {
IOUtils.closeQuietly(dataIn);
}
return result;
}
This method just deserializes the byte array to the correct object type, based on the provided class type token.
E.g:
Let's assume you have a custom ArrayWritable:
public class TextArrayWritable extends ArrayWritable {
public TextArrayWritable() {
super(Text.class);
}
}
Now you issue a single HBase get:
...
Get get = new Get(row);
Result result = htable.get(get);
byte[] value = result.getValue(family, qualifier);
TextArrayWritable tawReturned = asWritable(value, TextArrayWritable.class);
Text[] texts = (Text[]) tawReturned.toArray();
for (Text t : texts) {
System.out.print(t + " ");
}
...
Note:
You may have already found the readCompressedStringArray() and writeCompressedStringArray() methods in WritableUtils
which seem to be suitable if you have your own String array-backed Writable class.
Before using them, I'd warn you that these can cause serious performance hit due to
the overhead caused by the gzip compression/decompression.
Just came across the latest build of Mono.CSharp and love the promise it offers.
Was able to get the following all worked out:
namespace XAct.Spikes.Duo
{
class Program
{
static void Main(string[] args)
{
CompilerSettings compilerSettings = new CompilerSettings();
compilerSettings.LoadDefaultReferences = true;
Report report = new Report(new Mono.CSharp.ConsoleReportPrinter());
Mono.CSharp.Evaluator e;
e= new Evaluator(compilerSettings, report);
//IMPORTANT:This has to be put before you include references to any assemblies
//our you;ll get a stream of errors:
e.Run("using System;");
//IMPORTANT:You have to reference the assemblies your code references...
//...including this one:
e.Run("using XAct.Spikes.Duo;");
//Go crazy -- although that takes time:
//foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
//{
// e.ReferenceAssembly(assembly);
//}
//More appropriate in most cases:
e.ReferenceAssembly((typeof(A).Assembly));
//Exception due to no semicolon
//e.Run("var a = 1+3");
//Doesn't set anything:
//e.Run("a = 1+3;");
//Works:
//e.ReferenceAssembly(typeof(A).Assembly);
e.Run("var a = 1+3;");
e.Run("A x = new A{Name=\"Joe\"};");
var a = e.Evaluate("a;");
var x = e.Evaluate("x;");
//Not extremely useful:
string check = e.GetVars();
//Note that you have to type it:
Console.WriteLine(((A) x).Name);
e = new Evaluator(compilerSettings, report);
var b = e.Evaluate("a;");
}
}
public class A
{
public string Name { get; set; }
}
}
And that was fun...can create a variable in the script's scope, and export the value.
There's just one last thing to figure out... how can I get a value in (eg, a domain entity that I want to apply a Rule script on), without using a static (am thinking of using this in a web app)?
I've seen the use compiled delegates -- but that was for the previous version of Mono.CSharp, and it doesn't seem to work any longer.
Anybody have a suggestion on how to do this with the current version?
Thanks very much.
References:
* Injecting a variable into the Mono.CSharp.Evaluator (runtime compiling a LINQ query from string)
* http://naveensrinivasan.com/tag/mono/
I know it's almost 9 years later, but I think I found a viable solution to inject local variables. It is using a static variable but can still be used by multiple evaluators without collision.
You can use a static Dictionary<string, object> which holds the reference to be injected. Let's say we are doing all this from within our class CsharpConsole:
public class CsharpConsole {
public static Dictionary<string, object> InjectionRepository {get; set; } = new Dictionary<string, object>();
}
The idea is to temporarily place the value in there with a GUID as key so there won't be any conflict between multiple evaluator instances. To inject do this:
public void InjectLocal(string name, object value, string type=null) {
var id = Guid.NewGuid().ToString();
InjectionRepository[id] = value;
type = type ?? value.GetType().FullName;
// note for generic or nested types value.GetType().FullName won't return a compilable type string, so you have to set the type parameter manually
var success = _evaluator.Run($"var {name} = ({type})MyNamespace.CsharpConsole.InjectionRepository[\"{id}\"];");
// clean it up to avoid memory leak
InjectionRepository.Remove(id);
}
Also for accessing local variables there is a workaround using Reflection so you can have a nice [] accessor with get and set:
public object this[string variable]
{
get
{
FieldInfo fieldInfo = typeof(Evaluator).GetField("fields", BindingFlags.NonPublic | BindingFlags.Instance);
if (fieldInfo != null)
{
var fields = fieldInfo.GetValue(_evaluator) as Dictionary<string, Tuple<FieldSpec, FieldInfo>>;
if (fields != null)
{
if (fields.TryGetValue(variable, out var tuple) && tuple != null)
{
var value = tuple.Item2.GetValue(_evaluator);
return value;
}
}
}
return null;
}
set
{
InjectLocal(variable, value);
}
}
Using this trick, you can even inject delegates and functions that your evaluated code can call from within the script. For instance, I inject a print function which my code can call to ouput something to the gui console window:
public delegate void PrintFunc(params object[] o);
public void puts(params object[] o)
{
// call the OnPrint event to redirect the output to gui console
if (OnPrint!=null)
OnPrint(string.Join("", o.Select(x => (x ?? "null").ToString() + "\n").ToArray()));
}
This puts function can now be easily injected like this:
InjectLocal("puts", (PrintFunc)puts, "CsInterpreter2.PrintFunc");
And just be called from within your scripts:
puts(new object[] { "hello", "world!" });
Note, there is also a native function print but it directly writes to STDOUT and redirecting individual output from multiple console windows is not possible.
I have the following code with a simple class and a method for writing and then reading:
ObjectMapper mapper = new ObjectMapper();
try{
DataStore testOut = new DataStore();
DataStore.Checklist ch1 = testOut.addChecklist();
ch1.SetTitle("Checklist1");
String output = mapper.writeValueAsString(testOut);
JsonNode rootNode = mapper.readValue(output, JsonNode.class);
Map<String,Object> userData = mapper.readValue(output, Map.class);
}
public class DataStore {
public static class Checklist
{
public Checklist()
{
}
private String _title;
public String GetTitle()
{
return _title;
}
public void SetTitle(String title)
{
_title = title;
}
}
//Checklists
private Vector<Checklist> _checklists = new Vector<Checklist>();
public Checklist addChecklist()
{
Checklist ch = new Checklist();
ch.SetTitle("New Checklist");
_checklists.add(ch);
return ch;
}
public Vector<Checklist> getChecklists()
{
return _checklists;
}
public void setChecklists(Vector<Checklist> checklists)
{
_checklists = checklists;
}
}
The line:
String output = mapper.writeValueAsString(testOut);
causes an exception that has had me baffled for hours and about to abandon using this at all.
Any hints are appreciated.
Here is the exception:
No serializer found for class DataStore$Checklist and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: DataStore["checklists"]->java.util.Vector[0])
There are multiple ways to do it, but I will start with what you are doing wrong: your naming of getter and setter method is wrong -- in Java one uses "camel-case", so you should be using "getTitle". Because of this, properties are not found.
Besides renaming methods to use Java-style names, there are alternatives:
You can use annotation JsonProperty("title") for GetTitle(), so that property is recognized
If you don't want the wrapper object, you could alternatively just add #JsonValue for GetTitle(), in which case value used for the whole object would be return value of that method.
The answer seems to be: You can't do that with Json. I've seen comments in the Gson tutorial as well, that state that some serialization just doesn't work. I downloaded XStream and spat it out with XML in a few minutes of work and a lot less construction around what I really wanted to persist. In the process, I was able to delete a lot of code.