incorrect signature: void getDescribe() from the type Schema.DescribeFieldResult

Question

For the following 2 lines I am getting getting the error: Method does not exist or incorrect signature: void getDescribe() from the type Schema.DescribeFieldResult

Schema.DescribeFieldResult fieldResult = Schema.SObjectType.Case.fields.Type.getDescribe();

Schema.DescribeFieldResult fieldResult = Schema.SObjectType.Case.fields.Subtype__c.getDescribe();

I do not understand the error. Seems Like Type is a reserved word.

Answer 1

Schema.sObjectType is a DescribesObjectResult, which is why you need to use fields to get to the fields. If you want to get the field token, use <sobjectType>.<fieldName>.

The two following pieces of code are equivalent with regards to the DescribeFieldResult variable.

sObjectField field = Account.Type;
DescribeFieldResult describe = field.getDescribe();

DescribeFieldResult describe = sObjectType.Account.fields.Type;

Answer 2

Well, Type is the name of a class (and not one of the reserved keywords), but that's not the issue here.

Schema.SObjectType.Case.fields.Type and Schema.SObjectType.Case.fields.Subtype__c are already of type Schema.DescribeFieldResult as demonstrated in the example of using fields in the DescribeSObjectResult documentation

Schema.DescribeFieldResult dfr = Schema.SObjectType.Account.fields.Name;

DescribeFieldResult doesn't have a getDescribe() method (which makes sense, since it would just return itself).

The somewhat confusing bit is that while fields.<field api name> results in a DescribeFieldResult
fields.getMap() returns a Map<String, Schema.SObjectField>

So if you would use Schema.SObjectType.Case.fields.getMap().get('Type'), then you would need to follow that up with .getDescribe() to get the DescribeFieldResult.