I have a json lets say json 1
[
{
"id": "123",
"testname": "test123",
"name": "John Doe",
"active": true,
"type": "test6"
}
{
"id": "456",
"testname": "test564",
"name": "Ship Therasus",
"active": true,
"type": "test7"
}
.... some 100 entries
]
and json 2 some like below
[
{
"id": "123",
"country": "USA",
"state": "KA",
"age": 24,
"group": "g1"
}
{
"id": "456",
"country": "UK",
"state": "MA",
"age": 28,
"group": "G2"
}
...... 100 entries
]
Now Id is the constant thing between json1 and json2 I want to make a resultant json something like below lets call json3.I want to match the id and get country and state from json2 and append to json 1.I am not looking for code but if i do brute force it takes 100* 100 and hence performance issues. is there any better way to handle this in less complexity?
[
{
"id": "123",
"testname": "test123",
"name": "John Doe",
"active": true,
"type": "test6",
"country":"USA",
"state":"KA"
}
{
"id": "456",
"testname": "test564",
"name": "Ship Therasus",
"active": true,
"type": "test7",
"country":"UK",
"state":"MA"
}
]
The best approach to this problem is O(size(json1 || json2)), because inherently you will have to go through atleast one of the json lists fully to loop through all of the IDs. If you have a constant time lookup (like a hashmap, keyed by the ID), you will be able to pull the information about that specific ID. Honestly I'm not familiar enough with json to suggest a data structure to use, but I know in Java, hashmaps are a frequently used constant time lookup. The best approach would be:
Loop through one json list
Pull out the ID from each entry in this list
Look up the information from the other json list using the same ID
Combine all the information in a resulting json list
Although this answer is somewhat vague, I hope it helps.
Without making any assumptions, I can't think of any way to avoid the O(n^2) complexity based on the given information.
However, if your arrays were already sorted by the object id, you could speed it up by iterating over the array.
var json3 = [];
for(var i = 0; i < json1.length; i++) {
json3.push($.extend({}, json1[i], json2[i]));
}
If you have control over the data structure, an object that is keyed by the id would be much easier to work with than an array:
e.g.
json1 = {
"123": {"testname": "test123", ...},"456": {...}
}
Then your code would simply
var json3 = {};
for(var id in json1) {
json3[id] = $.extend({}, json1[id], json2[id]));
}
Related
I'm developing an Android application that needs to contact an API REST that gives a JSON structured as follow
{
"TEST1": [
{
"delegate": true,
"unit": "mmHg",
"code": "DIA",
"read": true,
"write": true
},
{
"delegate": true,
"unit": "mmHg",
"code": "SYS",
"read": true,
"write": true
}
],
"TEST2": [
{
"delegate": true,
"unit": "°C",
"code": "TEMPERATURE",
"read": true,
"write": true
}
]}
Now I thought to map the inner object in the array as a simple Java Object (e.g MyObject) with 5 fields, but how can I map the entire Object when I do the retrofit call? I don't think that
List<List<MyObject>>
would fit this case since I need to know the keys ("TEST1", "TEST2").
Any help will be appreciated
Maybe the best choice is to map the response in a JsonObject and then take the values with
JsonArray test1 = jsonObject.getAsJsonArray("TEST1");
you could use a counter based on the response's length to make it more dynamic like:
int testCounter = 0;
JsonArray test1 = jsonObject.getAsJsonArray("TEST");
inside a loop of course
For example, I have a index named 'student':
{
"id": "100",
"name": "Frank"
}
then there is another index named 'grade':
{
"id": "1"
"score": 95,
"studentId": "100"
}
how can I use one query to get a page of student and sort by score?
Can I use join query to search these two indices like MySQL?
This is what I want to get:
{
"id": "100",
"name": "Frank",
"score": "95"
},
{
...
}
Unfortunately no. Gotta normalize your data since joins are not possible in ES. More at elastic.co/guide/en/elasticsearch/guide/current/relations.html
i wanna retrieve map(ArrayList) according to the key, help me with the code below
public class MainActivity extends AppCompatActivity {
Map<String,ArrayList<Model>> map=new ArrayMap<>(); <----
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
......
.....
for (int j=0;j<jsonArray.length();j++)
{
JSONObject tempObj=jsonArray.getJSONObject(j);
String price =tempObj.getString("price");
String product=tempObj.getString("Product");
String qty=tempObj.getString("Qty");
modelList.add(new Model(id,price,product,qty,date));
map.put(key,modelList); <----
modelList.clear();
}
......
......
//here to retrieve that map in the same mainactivity
CODE....??????? <----
here is my json where those months are dynamic (jan, april, jun,...they are not constant).
{
"response": "success",
"servicecode": "134",
"forecast": {
"month": {
"jan": [
{
"id": "1",
"price": "12",
"Product": "1086",
"Qty": "14"
},
{
"id": "2",
"price": "19",
"Product": "1746",
"Qty": "45"
}
],
"april": [
{
"id": "3",
"price": "89",
"Product": "1986",
"Qty": "15"
},
{
"id": "1",
"price": "12",
"Product": "1086",
"Qty": "145"
}
],
"jun": [
{
"id": "81",
"price": "132",
"Product": "17086",
"Qty": "1445"
},
{
"id": "11",
"price": "132",
"Product": "10786",
"Qty": "1445"
}
]
}
},
"message": "Competitor Sales."
}
what i did is i took all the response separately with the key and stored in MAp, now what i want to do is to display the array in according to month in View pager. so tell me map'll do good or any alternative....
You're definitely on the right idea with maps, since you're able to assign each month an object.
However, you may want to consider using a LinkedHashMap instead of an ArrayMap because a LinkedHashMap preserves the insertion order, while ArrayMap's docs does not mention preserving insertion order anywhere.
The reason preserving insertion is important is because the months object in the JSON are presented in the order that you want to display it in. Therefore, if you parse "January" first, it will be guaranteed to be at the front of the Map.
You can declare and initialize a LinkedHashMap as follows:
Map<String, ArrayList<Model>> map = new LinkedHashMap<>();
I am assuming that you have correctly parsed this json into your objects, since you did not say anything in regards to the map being incorrectly populated, and by the placement of your arrows "<-----"
Now, for the code to actually use the Map.
for (String monthName : map.keySet()) {
ArrayList<Model> modelArray = map.get(monthName);
//now do whatever your view pager needs to do with this Model and its fields
for (Model model : modelArray) {
String price = model.getPrice(); //if you have a getter
String product = model.product; //if the field is public
}
}
Notes:
Using the LinkedHashMap's keyset is valid because the documentation guarantees that the keyset will be in insertion order. Also, this SO answer also confirms this fact.
I personally recommend GSON for parsing JSON objects, but since you seem to be okay with the parsing, this is not a big deal.
If you put ArrayMap correctly, you could get it as below:
Model model = map.get("april");
String id = model.id;
String price = model.price;
.....
You should ensure the key variable in your codes is a month name.
Is the month the key of your map?
If so, then you could simply define a list of months and retrieve the values accordingly, something like this:
for(String month: Arrays.asList("jan", "feb", "mar", "apr", "...")) {
if(map.containsKey(month)) { //skip months if not present
//--> code here
Model model = map.get(month);
}
}
I am trying to traverse through this JSON using Jackson.
ObjectNode dd = (ObjectNode) definition.get("views").get("joins");
It returns a NullPointerException.
Tried out multiple ways using ArrayNode also but the error still exists.
Basically it is not able to find the ArrayNode "joins".
Can someone help and let me know where I am making the mistake?
Below is the JSON.
{
"id": "SmartVitalSigns",
"type": {
"Age": "12"
},
"views": [{
"type": "Ind",
"query": {
"type": "query",
"name": "Height"
},
"joins": [{
"type": "in",
"definition": "Obj",
"link": {
"type": "element",
"definition": "Nation"
}
}]
}]
}
In your main object, the value of views is an array. If you know that it has only one element, you can access it via definition.get("views").elements().next().get("joins").
Note that joins is an array, too, so you also need to access its element(s) in a similar way.
I have a json file which has following structure:
{
"Otions": true
"Plastic": ""
"Houses": {
7: {
"name": "Akash Bhawan"
"MemBers": 3
"children": 1
}-
8: {
"name": "Ashiyana"
"memBers": 4
"children": 2
}-
9: {
"name": "Faruks Nest"
"memBers": 5
"children": 1
}-
The objects inside Houses are variable and can increase or decrease accordingly and also change names.
How ever the fieds "name", "members", "children" are the only fields and will always be there
i am using gson to parse
#SerializedName("Otions")
private String Options;
#SerializedName("Plastic")
private String plastics;
#SerializedName("Houses")
private Houses houses;
i want to know if there is a way we can i can store differently named objects in a hashtable or some other way?
If you can't change the structure then you have to make house as Hashmap of int to object. For Example:-
HashMap<int, Object> House;
And that object will have elements like name, memBers, details.
Houses should be a map like this.
private HashMap houses.
Since the 3: indicates an index-structure. Gson will create the nested objects as needed.
Please make "house" as bunch of array instead of objects.
{
"Options": true,
"Plastics": "",
"house": [{
"name": "Akash Bhawan",
"MemBers": 3,
"children": 1
}, {
"name": "Ashiyana",
"memBers": 4,
"children": 2
}, {
"name": "Faruks Nest",
"memBers": 5,
"children": 1
}]
}
You should do something like (as said in my comment):
JSONObject jsonHouses = jsonObject.getJSONObject("Houses");
Iterator<String> keys = jsonHouses.keys(); //this will be array of "7", "8", "9"
if (keys.hasNext()) {
JSONObject singleHouseObject = jsonHouses.getJSONObject(keys.next());
//now do whatever you want to do with singleHouseObject.
//this is the object which has "name", "MemBers", "children"
}