CSV generator does not support array values ​​for properties

Question

I am trying to develop an application that converts JSON to CSV .

I use JACKSON to parse JSON and write CSV .

Here is an example JSON I am trying to parse:

{ "_id" : 0, "name" : "aimee Zank", "scores" : [ { "type" : "exam", "score" : 1.463179736705023 }, { "type" : "quiz", "score" : 11.78273309957772 }, { "type" : "homework", "score" : 6.676176060654615 }, { "type" : "homework", "score" : 35.8740349954354 } ] } { "_id" : 1, "name" : "Aurelia Menendez", "scores" : [ { "type" : "exam", "score" : 60.06045071030959 }, { "type" : "quiz", "score" : 52.79790691903873 }, { "type" : "homework", "score" : 71.76133439165544 }, { "type" : "homework", "score" : 34.85718117893772 } ] } { "_id" : 2, "name" : "Corliss Zuk", "scores" : [ { "type" : "exam", "score" : 67.03077096065002 }, { "type" : "quiz", "score" : 6.301851677835235 }, { "type" : "homework", "score" : 20.18160621941858 }, { "type" : "homework", "score" : 66.28344683278382 } ] } 

Two Java classes:

Jsonnode class

 public class JsonNode { private String _id; private String name; private Collection<ScoreType> scores; /** * @return the _id */ public String get_id() { return _id; } /** * @param _id the _id to set */ public void set_id(String _id) { this._id = _id; } /** * @return the name */ public String getName() { return name; } /** * @param name the name to set */ public void setName(String name) { this.name = name; } /** * @return the scores */ public Collection<ScoreType> getScores() { return scores; } /** * @param scores the scores to set */ public void setScores(Collection<ScoreType> scores) { this.scores = scores; } } 

Class ScoreType

 public class ScoreType { private String type; private String score; /** * @return the type */ public String getType() { return type; } /** * @param type the type to set */ public void setType(String type) { this.type = type; } /** * @return the score */ public String getScore() { return score; } /** * @param score the score to set */ public void setScore(String score) { this.score = score; } } 

Method that converts JSON to CSV

  ObjectMapper mapper=new ObjectMapper(); JsonNode jsonNode=mapper.readValue(new File("C:\\...\\...\\...\\test.json"), JsonNode.class); CsvMapper csvMapper=new CsvMapper(); CsvSchema schema=csvMapper.schemaFor(JsonNode.class); schema=schema.withColumnSeparator(';'); ObjectWriter myObjectWriter=csvMapper.writer(schema); FileOutputStream tempFileOutputStream=new FileOutputStream(out+"\\jsontocsv.csv"); BufferedOutputStream bufferedOutputStream=new BufferedOutputStream(tempFileOutputStream); OutputStreamWriter writerOutputStream=new OutputStreamWriter(bufferedOutputStream,"UTF-8"); myObjectWriter.writeValue(writerOutputStream,jsonNode); 

Console output:

 com.fasterxml.jackson.core.JsonGenerationException: CSV generator does not support 

Array Values ​​for Properties

CSV Output:

 "0";"aimee Zank"; 

This is what I have done so far.

So, I ran into two problems:

1) The output CSV is not completed, it creates only one line and does not record points.

2) Error in the console.

I am using the following JACKSON :

  <dependency> <groupId>com.fasterxml.jackson.dataformat</groupId> <artifactId>jackson-dataformat-csv</artifactId> <version>2.4.0</version> </dependency> 

Can someone help me solve these problems?

I hope I was clear enough.

CSV Editing I expect:

 _id;name;scores.type;scores.score;scores.type;scores.score;scores.type;scores.score 0;aimee Zank;exam;1.46;quiz;11.78;homework;6.67;homework;35.87 

Ismail

Answer 1

Since CSV is a tuple of simple values, it really does not support collections (JSON arrays) as column values. You have Collection<ScoreType> as one of your bean properties, and this is causing your error.

Suggestion: Add a String getter that turns your collection into a string, and manually create a CSV schema to avoid using the Collection-value column automatically.