How do I extract unique data from Hyperledger Composer using query or js

Question

I want to get unique data from a duplicates data at Hyperledger Composer. How can I achieve this?

suppose I have a data like this

     [
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "1",
 "dataType" : "in",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "2",
 "dataType": "in",
 "productName": “A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "BABA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "3",
 "dataType": "out",
 "productName": "C",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "4",
 "dataType": "in",
 "productName": "C",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "5",
 "dataType": "out",
 "productName": "B",
 "quantity": 1,
 "country": "Unknown",
 "owner": "BABA"
}
] 

what I want to get is a list of unique Product name.

So the result I want maybe something like this

 [
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "1",
 "dataType" : "in",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "3",
 "dataType": "out",
 "productName": "C",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "5",
 "dataType": "out",
 "productName": "B",
 "quantity": 1,
 "country": "Unknown",
 "owner": "BABA"
}
] 

I don't really care about the sequence. I just want to know what productName do I have in my database.

I think this needs something to do with the logic.js part. I can do queries and get the data using post method. But I don't know how to do that using logic.js

I don't know how to get the data from logic.js. The example at official page only delete or trade. They don't return a new data.

any help is appreciated. I want to know how to send data using the js.

Answer 1

The js code to get the unique productname from your data would be

const data =[
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "1",
 "dataType" : "in",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "3",
 "dataType": "out",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "5",
 "dataType": "out",
 "productName": "B",
 "quantity": 1,
 "country": "Unknown",
 "owner": "BABA"
}
];

const distinctProductName = [...new Set(data.map(x => x.productName))];

You will have your distinct ProductName in distinctProductName but you won't have the details of product. From your questions, it didnot feel necessary too. If you need the details too, you could do something like

const data =[
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "1",
 "dataType" : "in",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "3",
 "dataType": "out",
 "productName": "A",
 "quantity": 1,
 "country": "Unknown",
 "owner": "GAGA"
},
{
 "$class": "org.stock.mynetwork.Commodity",
 "time": "5",
 "dataType": "out",
 "productName": "B",
 "quantity": 1,
 "country": "Unknown",
 "owner": "BABA"
}
];

const result = Array.from(new Set(data.map(x => x.productName)))
                    .map(productName => {
                             return{
                                    productName: productName,
                                    dataType : data.find(x => x.productName ===productName).dataType
                                   //you can obtain other values as I obtained dataType
                                   };
                              });

You will have your data in result.