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 /*
  * Copyright 2007 Daniel Spiewak
  * 
  * Licensed under the Apache License, Version 2.0 (the "License"); 
  * you may not use this file except in compliance with the License. 
  * You may obtain a copy of the License at
  * 
  *	    http://www.apache.org/licenses/LICENSE-2.0 
  * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.java.ao.schema;

Superinterface to all field name converters; designed to impose conventions upon the auto-conversion of method names to database fields. The idea behind this is to allow user-specified field name conventions and standards rather than always enforcing ActiveObjects's idea of "good naming".

Every net.java.ao.EntityManager contains a single field name converter which the entire library uses when performing operations. Any third-party code which interacts with database fields can also make use of this class. However, it's significantly harder to do so because Java doesn't support method literals.

Most new implementations of field name converters should extend AbstractFieldNameConverter rather than implementing this interface directly. This allows third-party converters to take advantage of boiler-plate conversion code which would otherwise have to be duplicated in every converter.

Author(s):
Daniel Spiewak
public interface FieldNameConverter {

Generates a field name to correspond with the specified method. The algorithm used must not only be aware of the defined conventions (such as getters and setters) but also the annotations sometimes used to override the field name explicitly. AO will not test for these annotations separately from the field name converter.

Parameters:
method The method for which a corresponding field name must be generated.
Returns:
A database field name which corresponds to the given method.
	public String getName(Method method);

Generates a secondary field name which corresponds with the polymorphic type flag for the field corresponding to the specified method. If the method in question does not represent a polymorphic field, this method may return any value, or null. For most use-cases, the return value of this method will be identical to that of the getName(java.lang.reflect.Method) method with a conventional suffix (usually "Type" or "_type") to indicate that it is a polymorphic flag. Polymorphic fields are the only scenario in which two fields will correspond to a single method.

An example of a table with a polymorphic flagging field could be taken as follows (MySQL DDL):

CREATE TABLE comments (
     id INTEGER NOT NULL AUTO_INCREMENT,
     title VARCHAR(45),
     text TEXT,
     commentableID INTEGER,
     commentableType VARCHAR(255),
     PRIMARY KEY(id)
 );

Notice the absence of foreign key constraint on the commentableID field. This is because this table has a one-to-many mapping with potentially numerous tables which can be described as "commentable". Thus, commentableID and commentableType describe a polymorphic one-to-many relationship within the database.

Parameters:
method The method for which a corresponding field name must be generated.
Returns:
A database field name which corresponds to the given method.
	public String getPolyTypeName(Method method);
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