Access SymbolTable methods field using Rest Tooling API

Question

String endpointUrl = URL.getSalesforceBaseUrl().toExternalForm() +
                     + '/services/data/v38.0/tooling/query/? + 
                     + q=Select+Id,Name,SymbolTable,Body+From+ApexClass+where+Id= Apex class salesforce id';

I am able to get following information through above query using tooling api :

SymbolTable={constructors=(), externalReferences=(), id=01p2800000E0Fc2AAF, innerClasses=(), interfaces=(), key=01p2800000E0Fc2AAF, methods=({annotations=(), location={column=41, line=4}, modifiers=(static, public), name=getItems, parameters=(), references=(), returnType=LIST, type=null}, {annotations=(), location={column=35, line=12}, modifiers=(static, public), name=saveItem, parameters=({name=item, type=Camping_Item__c}), references=(), returnType=Camping_Item__c, type=null}), name=CampingListController, namespace=null, parentClass=, ...},

I want to fetch symbol Table field methods explicitly to know the methods in apex class and its parameters. Any idea how to parse the SymbolTable fields?

I have referred following document : link

Answer 1

If you feed the response payload into JSON2Apex, it will give you a bit of a beast. In this case, if you only care about method names, you can simplify it quite a bit. Here are the class definitions you would need in order to deserialize:

class QueryResult
{
    final List<Record> records;
}
class Record
{
    final SymbolTable symbolTable;
}
class SymbolTable
{
    final List<Method> methods;
}
class Method
{
    final String name;
    final List<Parameter> parameters;
}
class Parameter
{
    final String name, type;
}

If you plug the above into Execute Anonymous, you can add this script and get the method names for a particular class:

String baseUrl = URL.getSalesforceBaseUrl().toExternalForm();
String path = '/services/data/v38.0/tooling/query/?q=';
String query = 'Select+Id,Name,SymbolTable,Body+From+ApexClass+WHERE+Name=\'DML\'';

HttpRequest request = new HttpRequest();
request.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionId());
request.setEndpoint(baseUrl + path + query);
request.setMethod('GET');

QueryResult result = (QueryResult)JSON.deserialize(
    new Http().send(request).getBody(), QueryResult.class
);

List<Method> methods = result.records[0].symbolTable.methods;
// now you have all methods with their name and parameters

Set<String> methodNames = new Set<String>();
for (Method method : methods) methodNames.add(method.name);
// now you have unique method names