Apex Anon - Scan for External IDs

scan-for-external-ids.java

List<SObjectType> types = new List<SObjectType> {
  Account.getSObjectType(),
  Contact.getSObjectType(),
  Opportunity.getSObjectType(),
  Lead.getSObjectType()
};

List<Field> fields = new List<Field>();
for (SObjectType t : types) {
  Schema.DescribeSObjectResult dsor = t.getDescribe();
  Map<String, Schema.SObjectField> fieldMap = dsor.fields.getMap();

  for (String key : fieldMap.keySet()) {
    Schema.DescribeFieldResult dfr = fieldMap.get(key).getDescribe();

    if (dfr.isExternalId()) {
      fields.add(new Field(dsor.name, dfr.name, dfr.getType(), true));
    }
  }
}

System.debug(String.format('Found {0} External Ids', new List<Integer> { fields.size() }));
System.debug(fields);

class Field {
  String sobjectName { get; set; }
  String fieldName { get; set; }
  DisplayType fieldType { get; set; }
  Boolean isExternalId { get; set; }

  Field(String obj, String f, Schema.DisplayType t, Boolean isExternalId) {
    sobjectName = obj;
    fieldName = f;
    fieldType = t;
    this.isExternalId = isExternalId;
  }
}