How to use third party rest api json data to create Opportunity in salesforce?

Question

I have JSON something like below and my code is written for an update as well as an insert but if I'm trying to insert another set of records it will only go to update since I iterating only OppMap which is nothing but Opportunity Records. what I want is when I try to insert another set some values match with project id needs to update and the remaining value need to insert in Opportunity

[
   {
      "OWNER_TYPE":"Government",
      "ProjectId":"001"
   },
   {
      "OWNER_TYPE":"Government",
      "ProjectId":"002"
   }
]
    List<object> arr =(List<object>)JSON.deserializeUntyped(response.getBody()); 
List<Opportunity> opList = new List<Opportunity>();
List<Opportunity> opListUpd = new List<Opportunity>();
Map<String,Object> mp_StrObj = new Map<String,Object>();
Map<String,Object> newMap = new Map<String,Object>();

for(object obj :arr)
{
    mp_StrObj = (Map<string,Object>)obj;
    newMap.put(string.valueof(mp_StrObj.get('ProjectId')),mp_StrObj);
    
}
system.debug('val'+newMap); 
    System.debug('mp_StrObj'+mp_StrObj);
Map<String, Opportunity> OppMap = new Map<String, Opportunity>([SELECT Id,RecordTypeId,Name,CloseDate,StageName,ProjectId FROM Opportunity WHERE ProjectId IN :newMap.keySet()]);

for (String eachIdFromMap : newMap.keyset())
{
    System.debug('clsDataMap'+newMap);
    System.debug('e'+eachIdFromMap);
    System.debug('OppMap'+OppMap);
    if(!OppMap.isEmpty()){
        for(Opportunity le:OppMap.values())
        {
            if(!OppMap.isEmpty() && le.ProjectId== eachIdFromMap)
            {
                System.debug('update'); 
                
                le.CloseDate=Date.today();
                le.RecordTypeId='01228000001HoFFAA0';
                le.Name='Testupd'+String.valueof(mp_StrObj.get('PROJECTID'));
                le.StageName='S0 - Prospecting';
                opListUpd.add(le);
            }
            else
            {
              Opportunity Opp = new Opportunity();
              Opp.CloseDate=Date.today();
               Opp.Name='Test'+String.valueof(mp_StrObj.get('PROJECTID'));
              Opp.StageName='S0 - Prospecting';
               opList.add(Opp);
             }
        }
    }
    if(OppMap.isEmpty())
    {
        System.debug('insert');
    Opportunity Opp = new Opportunity();
    Opp.CloseDate=Date.today();
    Opp.Name='Test'+String.valueof(mp_StrObj.get('PROJECTID'));
    Opp.StageName='S0 - Prospecting';
    opList.add(Opp);
    }
    System.debug('opListUpd'+opListUpd);
    System.debug('opList'+opList);
    if(opListUpd.size()>0)
    {
        update opListUpd;
    }
    if (opList.size()>0){
        insert opList;
    }

Answer 1

We can't give you specific code, as you've not asked a specific question. In the most general sense, you will:

Make the Callout

Use HttpRequest, Http, and HttpResponse to build, send, and receive a response from the external service.

Parse the Data

You will then use the JSON class to parse your response, typically via deserialize or deserializeUntyped, depending on your needs.

Create the Record

You will then create the record in Apex.

Without more details, we don't be able to help you much further. Everything you need to know is out there, but you will need to do some reading.