i am trying to generate a class model from an APIs JSON response (List), i use some service for auto-generation, and everything seems to work fine until the response JSON start returning attributes with a null value and the other thing is that some attributes are missing when i call the APIs. EX:
response JSON:
[
{
"persone": {
"name": "To John",
"age": 15
},
"group": "ipsum"
},
{
"persone": {
"name": "To John",
"age": null
},
"group": "ipsum"
},
{
"persone": {
"name": "To John"
}
}
]
in the above example, the age attribute is null, and the group attribute is missing in the last object of the list.
My question is how do you create an appropriate class model in that case handling the null and the missing attribute?
I have following json.
{
"Id": "357",
"Start": 76341,
"long": 0,
"data": "{bytesIn:120, byteOut:120}"
},
What I need to do is to take the value({bytesIn:120, byteOut:120}) from parametr "data" and move to the same level like "long", "start". The output should looks like this json"
{
"Id": "357",
"Start": 76341,
"long": 0,
"bytesIn": 120,
"byteOut": 120
},
Is there any "nice way" to do this in java, using ObjectMapper?
I suppose you use Jackson. Add #JsonUnwrapped on data field
class YourType {
#JsonUnwrapped
private Data data;
}
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.
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.
In my project when i send Rest Response to Advance Rest Client It only shows Fields which Have some values and Ignores(Does not show) fields which have NULL Values or Empty values.
Part Of Code:
Gson gson=new Gson();
// firstResponse is Object which contains the values
String jsonString = gson.toJson(firstResponse);
test.saveJson(jsonString); //OR System.out.println(jsonString);
return Response.ok(firstResponse).build(); // Response to Rest Client
Response sample To return Response.ok(firstResponse).build();
Advance rest client From web project :
{
"Name": "smith",
"Properties": {
"propertyList": [
{
"ID": "072",
"Number": "415151",
"Address": "Somewhere"
},
{
"ID": "151",
"Number": "a800cc79-99d1-42f1-aeb4-808087b12c9b",
"Address": "ninink"
},
{
"ID": "269",
},
],
},
}
Now when i save this as Json String in DB or When i want to Print this to console it also prints the fiels with null or empty values:
{
"Name": "smith",
"Properties": {
"propertyList": [
{
"ID": "072",
"Number": "415151",
"Address": "Somewhere"
},
{
"ID": "151",
"Number": "a800cc79-99d1-42f1-aeb4-808087b12c9b",
"Address": "ninink"
},
{
"ID": "269",
"Number": "",
"Address": ""
},
],
},
"resultList" :[]
}
How can i print or save this JSON string same as response in rest client i.e. i dont want to print null or empty value field i just want to ignore them.
in top og entity class , try with the annotation
#JsonInclude(Include.NON_EMPTY)
this annotation don't show any empty field in your json.
Not giving you a code but here are some pointers for you:
Read the manual: How to handle NULL values
You may need to use a custom exclusion strategy
Also read this Q&A: Gson: How to exclude specific fields from Serialization without annotations