code: function (Schema, fieldName, parent) {
  		var schema = new Schema();
  		var name = fieldName.replace(this.KEY_FIELD_REG_EXP, this._patchFormat(schema));
  
  		return parent.field(name).like(schema);
  	}
docs: parse fieldKey to field schema.
  add field schema to parent schema
  
  @method
  @private
  @param {String#constructor} Schema
  @param {String} fieldName
  @param {Schema} parent
  @returns {Schema} child field schema