I have the following data structure in an array from Neo4j.

DATA: [
  {
    "keys": [
      "J"
    ],
    "length": 1,
    "_fields": [
      {
        "identity": {
          "low": 9,
          "high": 0
        },
        "labels": [
          "Journal"
        ],
        "properties": {
          "body": "123"
        },
        "elementId": "9"
      }
    ],
    "_fieldLookup": {
      "J": 0
    }
  },
  {
    "keys": [
      "J"
    ],
    "length": 1,
    "_fields": [
      {
        "identity": {
          "low": 6,
          "high": 0
        },
        "labels": [
          "Journal"
        ],
        "properties": {
          "name": "Journal 221204",
          "body": "<p>Test!</p>",
          "lastEdit": "221204_03:53:02 PM",
          "createdOn": "221204_03:45:33 PM"
        },
        "elementId": "6"
      }
    ],
    "_fieldLookup": {
      "J": 0
    }
  }
]

I am trying to loop over the array, add specific data to a new array (finalList), and return the new array with this code.

// Allow require
import { createRequire } from "module";
const require = createRequire(import.meta.url);

require('dotenv').config()

var neo4j = require('neo4j-driver')

let finalList = [];

export default async function Database(query) {
  const Neo4jUser = process.env.Neo4jUser;
  const Neo4jPass = process.env.Neo4jPass;

  const uri = "";

  try {
    const driver = neo4j.driver(uri, neo4j.auth.basic(Neo4jUser, Neo4jPass));
    let session = driver.session();

    let result = await session.run(query);
    
    let records = Object.values(result)[0];
  
    console.log(Object.keys(records).length);

    if (Object.keys(records).length === 1) {
      let record = Object.values(records)[0];
        
      let fields = record._fields;

      let fields2 = fields[0];
      
      let properties = fields2.properties;

      console.log(properties);

      return properties;
    };

    if (Object.keys(records).length >= 2) {
      let count = Object.keys(records).length;

      console.log(2);

      console.log(count);

      let get_properties = async (records, countTimes) => {
        let record = Object.values(records)[countTimes];
        
        let fields = record._fields;
  
        let fields2 = fields[0];
        
        let properties = fields2.properties;
  
        console.log(properties);
  
        return properties;
      };

      let countTimes = 0;

      while (countTimes < count) {
        let node = get_properties(records, countTimes);

        finalList.concat(node.then());

        countTimes  
      };

      console.log(finalList);

      console.log(`DATA: ${records}`);
      
      return finalList
    };
  } 
  catch (err) {

    if (err.name == "Neo4jError") {
      node = "No Database found"
      return node;
    }
    else {
      console.log(err);
    }
  };
};

Every time I run the code, finalList is returned empty.

How can I add the appropriate data to an array and have it returned inside the function?

I understand that I am having a problem with the scope of finalArray inside the function, as I am not able to have finalList.concat "save" the data, but I am unable to find a solution to my problem after my research.

Also, can anyone suggest a more efficient way of sorting the data than what I have above?

Any help is appreciated!

CodePudding user response：

The problem is that node.then() doesn't return anything, so there is nothing to concat. Instead you would have to either pass a callback to .then() which will handle concatenating the lists or use await to wait till the value returned from get_properties() is resolved and then concat the lists.

I would suggest something like this,

// Function to asynchronously concat the lists
const async_concat = async(oldList, value) => {
  return oldList.concat(value);
}

// Make sure finalList is not const
var finalList = [];

while (countTimes < count) {
  // await the value of node and asynchronously concat the lists
  let node = await get_properties(records, countTimes);
  finalList = await async_concat(finalList, node);
  countTimes  
};