custom metata in apex used for field mapping

to store this information. Ideally you will need to have the following fields and you can build upon this.

1. Source Object - Name of the data source. Could be either a standard custom object, a JSON key.
2. Source Field - Specific field on the source if applicable
3. Source Datatype - Datatype of the field for type conversion
4. Target Object - API Name of the target Salesforce object
5. Target Field - API name of the field on the target Salesforce object
6. Target Datatype - Datatype of the field for type conversion

Once you build this, you will need to leverage Dynamic DML from Dynamic Apex (

)to create an Sobject instance at runtime based on the mapping and then put incoming data values to the appropriate target Sobject fields. Sample code is as below and you can build on it.

public class DataMappingService{
    //Constrcutor
    public DataMappingService(){}
	public void insertDynamic(String SobjectTypeName){
		//Create the instance of the object based on the custom settings
        Schema.SObjectType targetType = Schema.getGlobalDescribe().get(typeName);
        if (targetType == null){
            //throw an exception
        }
        //Dynamic instantitation of Sobject
        Sobject sobjectInstance = targetType.newSObject();
        //Assign source data values to the dynamic Sobject instance fields
		for(String fieldName :<List of fieldnames from Custom Settings>){
			sobjectInstance.put(fieldName, <Your data value>)
		}
		//Insert the data
		Database.insert(sobjectInstance);
    }
}