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Jackson JSON Deserialization - How to assign object members based on JSON values?

I have some ugly JSON that I need to deserialize which looks like the following:
"ContainerValues": [
{
"ParentAttribute": "QuantityContained",
"RowList": [
{
"Values": [
{
"Name": "Code",
"ValuesByLocale": {
"en-US": "GRM"
},
},
{
"Name": "Value",
"ValuesByLocale": {
"en-US": "4.0"
},
}
],
}
],
}
],
This is just a sample of the JSON I have. All I need to do is to get this into a POJO which looks like something like the following:
Class POJO{
String grmValue; // This is the "Value" for the GRM "Code" above, i.e. "4.0"
...
}
Any idea how I might be able to assign the value of grmValue based on the JSON above using Jackson? I'm starting to think I'll need to write a custom deserializer.

First You have to deserialize to class similar to your JSON, then transform to your POJO format :)

How to select fields in different levels of a jsonfile with jsonPath?

I want to convert jsonobjcts into csv files. Wy (working) attempt so far is to load the json file as a JSONObject (from the googlecode.josn-simple library), then converting them with jsonPath into a string array which is then used to build the csv rows. However I am facing a problem with jsonPath. From the given example json...
{
"issues": [
{
"key": "abc",
"fields": {
"issuetype": {
"name": "Bug",
"id": "1",
"subtask": false
},
"priority": {
"name": "Major",
"id": "3"
},
"created": "2020-5-11",
"status": {
"name": "OPEN"
}
}
},
{
"key": "def",
"fields": {
"issuetype": {
"name": "Info",
"id": "5",
"subtask": false
},
"priority": {
"name": "Minor",
"id": "2"
},
"created": "2020-5-8",
"status": {
"name": "DONE"
}
}
}
]}
I want to select the following:
[
"abc",
"Bug",
"Major",
"2020-5-11",
"OPEN",
"def",
"Info",
"Minor",
"2020-5-8",
"DONE"
]
The csv should look like that:
abc,Bug,Major,2020-5-11,OPEN
def,Info,Minor,2020-5-8,DONE
I tried $.issues.[*].[key,fields] and I get
"abc",
{
"issuetype": {
"name": "Bug",
"id": "1",
"subtask": false
},
"priority": {
"name": "Major",
"id": "3"
},
"created": "2020-5-11",
"status": {
"name": "OPEN"
}
},
"def",
{
"issuetype": {
"name": "Info",
"id": "5",
"subtask": false
},
"priority": {
"name": "Minor",
"id": "2"
},
"created": "2020-5-8",
"status": {
"name": "DONE"
}
}
]
But when I want to select e.g. only "created" $.issues.[*].[key,fields.[created]
[
"2020-5-11",
"2020-5-8"
]
This is the result.
But I just do not get how to select "key" and e.g. "name" in the field issuetype.
How do I do that with jsonPath or is there a better way to filter a jsonfile and then convert it into a csv?

I recommend what I believe is a better way - which is to create a set of Java classes which represent the structure of your JSON data. When you read the JSON into these classes, you can manipulate the data using standard Java.
I also recommend a different JSON parser - in this case Jackson, but there are others. Why? Mainly, familiarity - see later on for more notes on that.
Starting with the end result: Assuming I have a class called Container which contains all the issues listed in the JSON file, I can then populate it with the following:
//import com.fasterxml.jackson.databind.ObjectMapper;
String jsonString = "{...}" // your JSON data as a string, for this demo.
ObjectMapper objectMapper = new ObjectMapper();
Container container = objectMapper.readValue(jsonString, Container.class);
Now I can print out all the issues in the CSV format you want as follows:
container.getIssues().forEach((issue) -> {
printCsvRow(issue);
});
Here, the printCsvRow() method looks like this:
private void printCsvRow(Issue issue) {
String key = issue.getKey();
Fields fields = issue.getFields();
String type = fields.getIssuetype().getName();
String priority = fields.getPriority().getName();
String created = fields.getCreated();
String status = fields.getStatus().getName();
System.out.println(String.join(",", key, type, priority, created, status));
}
In reality, I would use a CSV library to ensure records are formatted correctly - the above is just for illustration, to show how the JSON data can be accessed.
The following is printed:
abc,Bug,Major,2020-5-11,OPEN
def,Info,Minor,2020-5-8,DONE
And to filter only OPEN records, I can do something like this:
container.getIssues()
.stream()
.filter(issue -> issue.getFields().getStatus().getName().equals("OPEN"))
.forEach((issue) -> {
printCsvRow(issue);
});
The following is printed:
abc,Bug,Major,2020-5-11,OPEN
To enable Jackson, I use Maven with the following dependency:
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.10.3</version>
</dependency>
In case you don't use Maven, this gives me 3 JARs: jackson-databind, jackson-annotations, and jackson-core.
To create the nested Java classes I need (to mirror the structure of the JSON), I use a tool which generates them for me using your sample JSON.
In my case, I used this tool, but there are others.
I chose "Container" as the name of the root Java class; a source type of JSON; and selected Jackson 2.x annotations. I also requested getters and setters.
I added the generated classes (Fields, Issue, Issuetype, Priority, Status, and Container) to my project.
WARNING: The completeness of these Java classes is only as good as the sample JSON. But you can, of course, enhance these classes to more accurately reflect the actual JSON you need to handle.
The Jackson ObjectMapper takes care of loading the JSON into the class structure.
I chose to use Jackson instead of JsonPath, simply because of familiarity. JsonPath appears to have very similar object mapping capabilities - but I have never used those features of JsonPath.
Final note: You can use xpath style predicates in JsonPath to access individual data items and groups of items - as you describe in your question. But (in my experience) it is almost always worth the extra effort to create Java classes, if you want to process all your data in more flexible ways - especially if that involves transforming the JSON input into different output structures.

How to get value from json object with java obect mapper

I want to get the value at the field first inside name.
How i can access in this field using HashMap in java
{ "payload":{
"name": {
"first": "jean",
"last": "bob,
},
"address": {
"code": "75",
"city": "paris",
"country": "France"
},
}}

Use one of the available Java libraries for handling JSON. E.g. Gson from Guava API. They are pretty straing fw.

Parse json response of rest API and delete certain jsonObjects - JAVA

I have a json file as below which I am getting as a response from rest API:
{
"label": " MARA LEYZIN",
"ClassCode": "PROFESSIONAL",
"actvFlg": "A",
"name": "MARA LEYZIN",
"Typ": {
"label": "C_TYP_LU",
"TypCode": "PROFESSIONAL "
},
"Address": {
"link": [],
"firstRecord": 1,
"pageSize": 10,
"searchToken": "multi",
"item": [
{
"label": "Address",
"addrTypFk": {
"label": "C_ADDRESS_TYPE_LU",
"addrTypCd": "INDUSTRY",
"addrTypDesc": "Industry"
}
}
]
}
I am trying to parse this in Java and to remove some unwanted json objects. Like I want the following string to be replaced by blank:
"link": [],
"firstRecord": 1,
"pageSize": 10,
"searchToken": "multi",
"item":
To achieve this I am trying the following approach:
String jsonStr = new String(Files.readAllBytes(Paths.get(inputFile)));
System.out.println(jsonStr);
jsonStr.replaceAll("link", "");
But it is not replacing the required string with blanks. Please help me in this.

string object is immutable , so basically if do you want to replace something
System.out.println(jsonStr.replaceAll("link", "")); this will print the replaced string but it will not affect the original string, however if you do this
jsonStr=jsonStr.replaceAll("link", "");
System.out.println(jsonStr); this will print the replaced string

First of all:
Your JSON is not validate. You're missing a closing curly bracket at the end of it.
{
"label": " MARA LEYZIN",
"ClassCode": "PROFESSIONAL",
"actvFlg": "A",
"name": "MARA LEYZIN",
"Typ": {
"label": "C_TYP_LU",
"TypCode": "PROFESSIONAL "
},
"Address": {
"link": [],
"firstRecord": 1,
"pageSize": 10,
"searchToken": "multi",
"item": [{
"label": "Address",
"addrTypFk": {
"label": "C_ADDRESS_TYPE_LU",
"addrTypCd": "INDUSTRY",
"addrTypDesc": "Industry"
}
}]
}
}
Second of all you should just change order of your commands to this:
jsonStr.replaceAll("link", "");
System.out.println(jsonStr);
Important addition:
And I would suggest you to use org.json library or even better JACKSON to parse JSON files.
Here's tutorial how to use jackson and it's my warmest suggestion.
You will save a lot of time and you can do whatever you like.

How to tell jackson to serialize to json without attributes prefix

In my Java IDE, I tell java that I use prefix for my fields.
The result is that during a Java to Json serialization, I get all my attributes prefixed with an _, is there a simple way to do so ?
Actual
{
"_creation": {
"_dateTime": "2016-08-16T11:13:09.000Z",
"_personId": 1
},
"_description": null,
"_firstName": "Jason",
"_id": 700,
"_lastName": "Stateman",
"_modification": {
"_dateTime": "2016-08-16T11:13:24.000Z",
"_personId": null
}
}
Wanted
{
"creation": {
"dateTime": "2016-08-16T11:13:09.000Z",
"personId": 1
},
"description": null,
"firstName": "Jason",
"id": 700,
"lastName": "Stateman",
"modification": {
"dateTime": "2016-08-16T11:13:24.000Z",
"personId": null
}
}

If you are using FasterXML to serialize your objects, you could add the #JsonProperty annotation to your class attributes to control the serialized attribute name. See the documentation at : https://github.com/FasterXML/jackson-annotations/wiki/Jackson-Annotations#property-naming