com.google.code.morphia.utils.FieldName Maven / Gradle / Ivy

Go to download
package com.google.code.morphia.utils;


import java.lang.IllegalStateException;
import java.lang.reflect.Field;


/**
 * Handy class to test if a certain FieldName is available in a class. Usage: If you add {@code public static final String _foo =
 * FieldName.of("foo"); }
 * 
 * you´ll see an Exception on loading the class. A nice side-effect: if you use this in Queries like {@code
 * q.field(MyEntity._foo).equal("bar") }
 * 
 * your IDE is able to track this usage. Using FieldName does not at all replace query validation.
 *
 * @author [email protected]
 */
public class FieldName {
  public static String of(final String name) {
    return of(callingClass(), name);
  }

  public static String of(final Class clazz, final String name) {
    Assert.parameterNotNull(clazz, "clazz");
    Assert.parameterNotNull(name, "name");
    if (hasField(clazz, name)) {
      return name;
    }
    throw new FieldNameNotFoundException("Field called '" + name + "' on class '" + clazz + "' was not found.");
  }

  private static boolean hasField(final Class clazz, final String name) {
    final Field[] fa = ReflectionUtils.getDeclaredAndInheritedFields(clazz, true);
    for (final Field field : fa) {
      if (name.equals(field.getName())) {
        return true;
      }
    }
    return false;
  }

  private static Class callingClass() throws IllegalStateException {
    return callingClass(FieldName.class);
  }

  private static Class callingClass(final Class... classesToExclude) {
    final StackTraceElement[] stackTrace = new Exception().getStackTrace();
    for (final StackTraceElement e : stackTrace) {
      final String c = e.getClassName();

      boolean exclude = false;
      for (final Class ec : classesToExclude) {
        exclude |= c.equals(ec.getName());
      }
      if (!exclude) {
        return forName(c);
      }
    }
    throw new IllegalStateException();

  }

  private static Class forName(final String c) {
    try {
      return Class.forName(c);
    } catch (ClassNotFoundException e) {
      throw new RuntimeException("Error when getting class for name '" + c + "'");
    }
  }

  public static class FieldNameNotFoundException extends RuntimeException {
    public FieldNameNotFoundException(final String msg) {
      super(msg);
    }
  }

}