node-red-contrib-jsonfilter/filter.js

Node-RED node that filters only required fields from objects in a JSON Array

"use strict";
module.exports = function (RED) {
    function Filter(config) {
        RED.nodes.createNode(this, config);
        this.fields = config.fields;
        var node = this;

	  function isEmptyObject(obj) {
			return !Object.keys(obj).length;
		}

	  function getKeys(data){

	  var keyList=Object.keys(data[0]);	  
      return keyList;

	  } 

	  
		
	   function lookUpAllKeys(fieldArray,data){

        var list=Object.keys(data[0]);

		
		var nonMatchingKeys =[];
		var match;   

              
		for(var j in fieldArray){
        

        match=false;  

		for(var i=0;i<list.length;i++){

		            
	    if (list[i].replace(/\s+/g, '').toUpperCase() === fieldArray[j].replace(/\s+/g, '').toUpperCase()){           
                match=true;          
		   }

		} 
		if(match === false ){
		  
           nonMatchingKeys.push(fieldArray[j]); 
		   
		}	
		     

       }
        return nonMatchingKeys;
      }

     

        this.on('input', function (msg) {
            if (node.cache === undefined) {
                node.cache = [];
            }
					
            var fieldArray = node.fields.split(",");

						
			var data = msg.payload;


			if(isEmptyObject(data))
			{
				node.error('Empty Input received in JSON Filter');
				return;

			} else{
				                                   
                var jsonStr=JSON.stringify(data);
				             
                try {
            
				 var parsedJson= JSON.parse(jsonStr); 			
				
			} catch (e) {
					
					node.error({"JSON Error in JSON Filter ":e});		
					return;
			} 

            }

            
		      
			var invalidKeys=[];

         
			invalidKeys=lookUpAllKeys(fieldArray,data);


			if(invalidKeys.length !== 0){
			
			node.error({"The following Fields in JSON Filter configuration does not have a match in the Data Headers ":invalidKeys});
			return;

			}
	 	
						
			var outputArray = [];

			var keyList=getKeys(data);

						
			for(var i = 0; i < data.length; i++) {

				var obj = data[i];
				
				var record = {};
				
				for(var j = 0; j < fieldArray.length; j++) { 
		  
        
                for(var k=0;k<keyList.length;k++){
			                				
				 
				if (keyList[k].replace(/\s+/g, '').toUpperCase() === fieldArray[j].replace(/\s+/g, '').toUpperCase()){ 
            

				record[fieldArray[j].trim()] = obj[keyList[k].trim()];
              
				break;   

		       }
              
	    	} 

				}

				outputArray.push(record);
			}
			msg.payload = outputArray;
            node.send(msg);	
			return;				
        });
    }
    RED.nodes.registerType("JSONFilter", Filter);
};