Using query select JSON * from table_name in cqlsh I can get results in JSON format. I want to do the same using Datastax Java API.
StringBuilder sb = new StringBuilder("SELECT json * FROM ").append("JavaTest.data");
String query = sb.toString();
ResultSet rs = session.execute(query);
List<Row> rows = rs.all();
String q1 = rows.toString();
System.out.println(q1);
But the result is :
[
Row [
{
"id":1,
"time":"12",
"value":"SALAM"
}
],
Row [
{
"id":2,
"time":" 89",
"value":" BYE"
}
],
Row [
{
"id":3,
"time":" 897",
"value":" HelloWorld"
}
]
]
that it is not in the correct JSON format. I know I can get the JSON of a row but in that way, I should use a loop to get all results in JSON format. Searching in JAVA API Docs I couldn't find any solution for this!
you need to use following - just get JSON strings as is:
for (Row row : rs) {
String json = row.getString(0);
// ... do something with JSON string
}
If you want to represent them as the list of objects, then it could be easier to add square brackets before & after iteration, and put comma between JSON objects, like this:
ResultSet rs = session.execute("select json * from test.jtest ;");
int i = 0;
System.out.print("[");
for (Row row : rs) {
if (i > 0)
System.out.print(",");
i++;
String json = row.getString(0);
System.out.print(json);
}
System.out.println("]");
Or you can write custom serializer for ResultSet, and put conversion task into it:
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addSerializer(ResultSet.class, new ResultSetSerializer());
mapper.registerModule(module);
rs = session.execute("select * from test.jtest ;");
String json = mapper.writeValueAsString(rs);
System.out.println("'" + json + "'");
This is much more complex task (you need correctly handle collections, user-defined types etc.), but you may have better control over serialization.
Full code is available at this gist. Please note that JSON serializer handles only NULL, boolean & int types - everything else is treated as string. But it's enough to understand an idea.
Related
I'm trying to parse Json in VBA.
I'm collecting data from an API that returns a json format in a string.
I use JsonConverter to parse my string.
Now when i want to search on it, i got an error 13 incompatibility type.
See my Java API below :
#GetMapping("/rest/collectData/excel/exportAll")
public HashMap<Object, Object> collectAll(){
HashMap<Object, Object> result = new HashMap<>();
String sql = "SELECT affair_code AS codeAffair, name, amount, end_date AS state FROM service_record WHERE affair_code IS NOT NULL AND affair_code != ''";
List<Map<String, Object>> allServiceRecords = jdbcTemplate.queryForList(sql);
if(allServiceRecords != null && allServiceRecords.size() >0){
result.put("result", true);
for(Map<String, Object> serviceRecord : allServiceRecords){
HashMap<Object, Object> details = new HashMap<>();
if(result.containsKey(serviceRecord.get("codeAffair"))){
details.put("alone", false);
details.put("message", "Plusieurs prestations ont été trouvées.");
} else {
details.put("alone", true);
details.put("name", (String) serviceRecord.get("name"));
details.put("amount", (Double) serviceRecord.get("amount"));
details.put("state", ((Date) serviceRecord.get("state")).compareTo(new Date()) < 0 ? "En cours" : "Clos");
}
result.put(serviceRecord.get("codeAffair"), details);
}
} else{
result.put("result", false);
result.put("error", "La liste n'est pas définie, ou vide.");
}
return result;
}
It returns json :
{"03-045251":{"alone":true,"amount":0.0,"name":"name1","state":"En cours"},"03_05494":{"alone":true,"amount":16743.0,"name":"name2","state":"En cours"}}
First, i execute sql request to collect my data and put it in a map.
Then, i send this map to my excel VBA.
Now see my VBA :
Sub JsonDataSqwal()
firstRow = Range("A" & 11).End(xlDown).Row
lastRow = Range("A" & Rows.Count).End(xlUp).Row
Dim httpObject As Object
Set httpObject = CreateObject("MSXML2.XMLHTTP")
sUrl = "http://localhost/rest/collectData/excel/exportAll"
sRequest = sUrl
httpObject.Open "GET", sRequest, False
httpObject.send
sGetResult = httpObject.responseText
If Not IsNull(sGetResult) Then
Dim oJson As Object
JsonConverter.JsonOptions.AllowUnquotedKeys = True
Set oJson = JsonConverter.ParseJson(sGetResult)
Dim i As Long
For i = firstRow To lastRow
Dim codeAffString As String
codeAffString = Cells(i, 4)
Debug.Print oJson(codeAffString)("name")
Next i
End If
End Sub
For the moment, i try to print my data. the loop collects values from a column, which contains all my codeAffair as 00_00000 or 00-00000
It is this data that i try to use in my vba code with the var codeAffString.
When i execute my code, i'm always getting error 13 about type incompatibility.
To solve this, i tried many things :
to add quote to my var
To rename my HashMap as HashMap<String, Object>
To allow unquoting keys
To change my back office program
To replace my value like """" + codeAffairString + """"
To replace my var with a fix String "00_00000". It works in this case.
To check the type of my var with VarTyp function which returns 8 for String index.
Now i Have no other idea to solve my problem..
If someone see where is my mistake..
Thank you !
Just a quick test:
I used the JSON string you gave and the value you gave for codeAffString to build a minimal reproducible example and it does not produce any errors:
Sub test()
Const JsonString As String = "{""03-045251"":{""alone"":true,""amount"":0.0,""name"":""name1"",""state"":""En cours""},""03_05494"":{""alone"":true,""amount"":16743.0,""name"":""name2"",""state"":""En cours""}}"
Const codeAffString As String = "03-045251"
Dim oJson As Object
JsonConverter.JsonOptions.AllowUnquotedKeys = True
Set oJson = JsonConverter.ParseJson(JsonString)
Debug.Print oJson(codeAffString)("name") ' outputs name1
End Sub
The error you describe occurs if codeAffString cannot be found in the JSON.
Test it by the following in your code:
For i = firstRow To lastRow
Dim codeAffString As String
codeAffString = Cells(i, 4)
If IsEmpty(oJson(codeAffString)) Then
Debug.Print codeAffString & " does not exist in the json"
Else
Debug.Print oJson(codeAffString)("name")
End If
Next i
TLDR:
I want to update certain value of a JsonNode key dependsOn and return the result as a JsonNode. Currently I'm converting the value to a String, slicing the characters and then using ObjectMapper to convert the string back to JsonNode
I have a json object like shown below
{
"name": "somename",
"type": "sometype",
"description": "some desc",
"properties": {
"path": "some path",
"dependsOn": [
"ABC:zzz","DEF:sdc","GHI:ere"
],
"checkpoint": "some checkpoint",
"format": "some format",
"output": "some output",
"table": "some table"
}
}
I'm currently parsing the above json data and fetching the dependsOn as JsonNode element (as shown below)
JsonNode components = model.get("properties");
JsonNode dependsOn = components.get("dependsOn");
When I print dependsOn it looks like this "["ABC:zzz","DEF:sdc","GHI:ere"]"
My requirement was to strip everything after : from the dependsOn array
This below code helped me to convert the JsonNode to String and then strip :whatever then convert it back to JsonNode
if (dependsOn != null && !dependsOn.isEmpty()) {
String dependsOnString =
components
.get("dependsOn")
.get(0)
.textValue()
.substring(
0,
(components.get("dependsOn").get(0).textValue().lastIndexOf(":") != -1)
? components.get("dependsOn").get(0).textValue().lastIndexOf(":")
: components.get("dependsOn").get(0).textValue().length());
ObjectMapper mapper = new ObjectMapper();
dependsOn = mapper.readTree("[\"" + dependsOnString + "\"]");
}
Input:
"["ABC:zzz","DEF:sdc","GHI:ere"]"
Output
"["ABC","DEF:sdc","GHI:ere"]"
Above code only strip the first element of the array I can loop and perform the same for rest of the elements though. But I have a couple of questions regarding whatever I'm trying to do
Firstly, am I doing this in a right way or is there a simpler
technique to do this? instead of converting it to string and then
again to JsonNode..
Next, I've only done this to the first element of the array
and I want to loop through and do this for all the elements of the array. Is there a simpler solution to this instead of using a for/while loop?
This should work, without convert to string and parse again to jsonNode
JsonNode prop = node.get("properties");
JsonNode arrayCopy = prop.get("dependsOn").deepCopy();
var array = ((ObjectNode)prop).putArray("dependsOn");
IntStream.range(0, arrayCopy.size())
.forEach(index -> {
String elem = arrayCopy.get(index).asText();
String finalElem = elem.substring(0,elem.contains(":") ? elem.lastIndexOf(':') : elem.length());
array.add(finalElem);
});
Since my usecase suggests my dependsOn value should not be overridden at node level, I had to convert the JsonNode to String and then used the regular expression matcher to replace :xyz with an empty string in each element then convert it back to JsonNode
String pattern = ":[a-zA-Z]+";
String newDependsOn = dependsOn.toString().replaceAll(pattern, "");
ObjectMapper mapper = new ObjectMapper();
dependsOn = mapper.readTree(newDependsOn);
#Gautham's solution did work too but what I think is it was overriding at the root and the old value wasn't available anymore outside the loop
You can iterate the dependsOn after casting it to ArrayNode and set value to it:
ArrayNode array = ((ArrayNode) dependsOn);
List<String> newValues = new ArrayList<>();
for(int i=0;i<array.size();i++) {
newValues.add(array.get(i).asText().split(":")[0]);
}
array.removeAll();
newValues.forEach(array::add);
EDIT: If you don't want your original dependsOn to be updated then use:
JsonNode copy = dependsOn.deepCopy();
// or you could invoke `deepCopy` on the `ArrayNode` as well
Now pass this copy object for slicing operation. So that the original json remains unchanged.
I am reading table from postgreSQL DB and populating all columns and its values in a json object.
One of the column in postgre is of type json. So the output has lot of escape characters. like below for key dummykeyname.
{
"XY": "900144",
"id": 1,
"date": 1556167980000,
"type": "XX50",
"dummykeyname": {
"type": "json",
"value": "{\"XXXX\": 14445.0, \"YYYY\": 94253.0}"
}
}
I want the output to look like
"value": "{"XXXX": 14445.0, "YYYY": 94253.0}"
Code i used is
JSONArray entities = new JSONArray();
var rm = (RowMapper<?>) (ResultSet result, int rowNum) -> {
while (result.next()) {
JSONObject entity = new JSONObject();
ResultSetMetaData metadata = result.getMetaData();
int columnCount = metadata.getColumnCount() + 1;
IntStream.range(1, columnCount).forEach(nbr -> {
try {
entity.put(result.getMetaData().getColumnName(nbr), result.getObject(nbr));
} catch (SQLException e) {
LOGGER.error(e.getMessage());
}
});
entities.add(entity);
}
return entities;
};
Library used:
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
Please guide me where am i going wrong.
Take a different approach.
1) first create a pojo of the required columns
ex : if your table has 4 columns
id, name, country, mobile create a class Employee and populate the class using rowmapper available in spring jdbc.
2) create a class EmployeeList, which has List , add each Employee objects created out of rowmapper to declared list.
3) use
a) ObjectMapper mapper = new ObjectMapper();
b) mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
c) mapper.writeValueAsString(EmployeeListobjects);
I am working on a Java api - using Spring Boot - I would like to create a controller that exports data from the db - into a csv that a user can download.
This is an example of what I have making Json responses.
// get chart
#SuppressWarnings("unchecked")
public Object getChart() {
// build clean object
JSONObject contents = new JSONObject();
//inverse bubble chart
JSONObject chart = new JSONObject();
chart.put("label", "250 applicants");
chart.put("value", 120);
contents.put("chart", chart);
contents.put("number", "0202 000 000");
JSONObject json = new JSONObject();
json.put("contents", contents);
return json;
}
I've seen this example -- but its being called from a reactjs framework - so not sure how I would fetch the HttpServletResponse?
Create and Download CSV file Java(Servlet)
would I invoke the api as usual?
//api/getMyCsv
#SuppressWarnings("unchecked")
#RequestMapping(value = {"/api/getMyC"}, method = RequestMethod.GET)
#CrossOrigin(origins = {"*"})
public ResponseEntity<?> getHome(
//HttpServletRequest request
) throws Exception {
JSONObject chart = getChart();
JSONArray data = new JSONArray();
data.add(chart);
//create empty response
JSONObject response = new JSONObject();
//create success response
response.put("data", data);
response.put("status", "success");
response.put("msg", "fetched csv");
return new ResponseEntity<>(response, HttpStatus.OK);
}
so with the react - using axios
export function fetchCsv(data) {
let url = "http://www.example.com/api/getMyC";
return function (dispatch) {
axios.get(url, {
params: data
})
.then(function (response) {
response = response.data.data;
dispatch(alertSuccess(response));
})
.catch(function (error) {
dispatch(alertFail(error));
});
}
}
CSV is just comma separated values right?
So, you can represent a row of data for example, as a class.
Take an address:
30 my street, my town, my country
if I wanted to represent that data as a class, and later as CSV data I'd make a class something like this:
public class AddressCSV{
private String street;
private String town;
private String country;
public AddressCSV(String street, String town, String country){
this.street = street;
this.town = town;
this.country = country;
}
// getters and setters here
// here you could have a method called generateCSV() for example
// or you could override the toString() method like this
#Override
public String toString(){
return street + "," + town + "," + country + "\n"; // Add the '\n' if you need a new line
}
}
Then you use it the same way as your JSONObject, except instead of returning the whole object you do return address.toString();
This is a very simple example of course. Checkout the StringBuilder class if your have a lot of things to build.
Overriding the toString() method means you can do things like pass your object like System.out.printline(address) and it will print the CSV.
The Spring way to help (un)marshaling data is to implement and register an HttpMessageConverter.
You could implement one that specifically handles MediaType text/csv, and supports whatever object types you decide to implement, e.g.
List<List<?>> - Row is a list of values, auto-converted to string.
List<Object[]> - Row is an array of values, auto-converted to string.
List<String[]> - Row is an array of string values.
List<?> - Row is an bean object, field names added as header row.
You may even implement your own field annotations to control column order and header row values.
You could also make it understand JAXB and/or JSON annotations.
With such a converter in place, it's now easy to write Controller methods returning CSV:
#GetMapping(path="/api/getMyC", produces="text/csv")
public List<String[]> getMyCAsCsv() {
List<Object[]> csv = Arrays.asList(
new Object[] { "First Name", "Last Name", "Age" },
new Object[] { "John" , "Doe" , 33 },
new Object[] { "Jane" , "Smith" , 29 }
);
return csv;
}
DO NOT try doing basic String trickery because the address, especially the street is bound to contain characters such as commas, quotes or line endings. This can easily mess up the CSV output. These characters need to be properly escaped in order to generate a parseable CSV output. Use a CSV library for that instead.
Example with univocity-parsers:
ResultSet rs = queryDataFromYourDb();
StringWriter output = new StringWriter(); //writing to a String to make things easy
CsvRoutines csvRoutine = new CsvRoutines();
csvRoutine.write(rs, output);
System.out.println(output.toString());
For performance, can write to an OutputStream directly and add more stuff to it after dumping your ResultSet into CSV. In such case you will want to keep the output open for writing. In this case call:
csvRoutine.setKeepResourcesOpen(true);
Before writing the ResultSet. You'll have to close the resultSet after writing.
Disclaimer: I'm the author of this library. It's open-source and free.
The JSON string is as follows
{
"rank":"-text_relevance",
"match-expr":"(label 'star wars')",
"hits":{
"found":7,
"start":0,
"hit":[
{"id":"tt1185834",
"data":{
"actor":["Abercrombie, Ian","Baker, Dee","Burton, Corey"],
"title":["Star Wars: The Clone Wars"]
}
},
.
.
.
{"id":"tt0121766",
"data":{
"actor":["Bai, Ling","Bryant, Gene","Castle-Hughes, Keisha"],
"title":["Star Wars: Episode III - Revenge of the Sith"]
}
}
]
},
"info":{
"rid":"b7c167f6c2da6d93531b9a7b314ad030b3a74803b4b7797edb905ba5a6a08",
"time-ms":2,
"cpu-time-ms":0
}
}
It has many fields, but I just have want the Data field. This won't work:
mapper.readvalue(jsonString,Data.class);
How do I make Jackson read just the "Data" field?
Jackson 2.3 now has a JsonPointer class you can use. There's a simple example in their quick overview for the release.
Usage is simple: for JSON like
{
"address" : { "street" : "2940 5th Ave", "zip" : 980021 },
"dimensions" : [ 10.0, 20.0, 15.0 ]
}
you could use expressions like:
JsonNode root = mapper.readTree(src);
int zip =root.at("/address/zip").asIntValue();
double height = root.add("/dimensions/1").asDoubleValue();// assuming it's the second number in there
I think that the easiest way to do this is using the Jackson TreeModel: let Jackson parse the JSON input into a JsonNode object that you then query, assuming some knowledge of the data structure. This way you can ignore most of the data, walking down the JsonNodes to the data that you want.
// String input = The JSON data from your question
ObjectMapper mapper = new ObjectMapper();
JsonNode rootNode = mapper.readValue(input.getBytes(), JsonNode.class);
// can also use ArrayNode here, but JsonNode allows us to get(index) line an array:
JsonNode hits = rootNode.get("hits");
// can also use ObjectNodes here:
JsonNode oneHit = null;
JsonNode dataObj = null;
int idx = 0;
Data data = null;
if (hits != null)
{
hits = hits.get("hit");
if (hits != null)
{
while ((oneHit = hits.get(idx)) != null)
{
dataObj = oneHit.get("data");
System.out.println("Data[" + idx + "]: " + dataObj);
idx++;
}
}
}
Output:
Data[0]: {"id":"tt1185834","data":{"actor":["Abercrombie, Ian","Baker, Dee","Burton, Corey"],"title":["Star Wars: The Clone Wars"]}}
Data[1]: {"id":"tt0121766","data":{"actor":["Bai, Ling","Bryant, Gene","Castle-Hughes, Keisha"],"title":["Star Wars: Episode III - Revenge of the Sith"]}}
You can still use your Data class implementation, but I believe this will require getting the String representing each data - as above relying on toString, or using JsonNode.getText() - and re-parsing it using the ObjectMapper:
mapper.readValue(dataArray, Data.class));
The alternative is to use the Jackson Streaming Model, and intercept the nodes yourself until you see the part of the input that marks the beginning of each data element, then consume the string and call objectMapper.readValue on the contents, for each string.
Json-path could be a very good alternative for such a requirement - if you are okay with a solution other than Jackson that is: http://code.google.com/p/json-path/