collection_mapping.pot

hibernate-distribution-3.3.1.GA-dist.zip源码

      "    <element column=\"name\" type=\"string\"/>\n"
      "</set>\n"
      "\n"
      "<map name=\"holidays\" sort=\"my.custom.HolidayComparator\">\n"
      "    <key column=\"year_id\"/>\n"
      "    <map-key column=\"hol_name\" type=\"string\"/>\n"
      "    <element column=\"hol_date\" type=\"date\"/>\n"
      "</map>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:638
#, no-c-format
msgid "Allowed values of the <literal>sort</literal> attribute are <literal>unsorted</literal>, <literal>natural</literal> and the name of a class implementing <literal>java.util.Comparator</literal>."
msgstr ""

#. Tag: para
#: collection_mapping.xml:644
#, no-c-format
msgid "Sorted collections actually behave like <literal>java.util.TreeSet</literal> or <literal>java.util.TreeMap</literal>."
msgstr ""

#. Tag: para
#: collection_mapping.xml:649
#, no-c-format
msgid "If you want the database itself to order the collection elements use the <literal>order-by</literal> attribute of <literal>set</literal>, <literal>bag</literal> or <literal>map</literal> mappings. This solution is only available under JDK 1.4 or higher (it is implemented using <literal>LinkedHashSet</literal> or <literal>LinkedHashMap</literal>). This performs the ordering in the SQL query, not in memory."
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:658
#, no-c-format
msgid ""
      "<![CDATA[<set name=\"aliases\" table=\"person_aliases\" order-by=\"lower(name) asc\">\n"
      "    <key column=\"person\"/>\n"
      "    <element column=\"name\" type=\"string\"/>\n"
      "</set>\n"
      "\n"
      "<map name=\"holidays\" order-by=\"hol_date, hol_name\">\n"
      "    <key column=\"year_id\"/>\n"
      "    <map-key column=\"hol_name\" type=\"string\"/>\n"
      "    <element column=\"hol_date type=\"date\"/>\n"
      "</map>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:660
#, no-c-format
msgid "Note that the value of the <literal>order-by</literal> attribute is an SQL ordering, not a HQL ordering!"
msgstr ""

#. Tag: para
#: collection_mapping.xml:665
#, no-c-format
msgid "Associations may even be sorted by some arbitrary criteria at runtime using a collection <literal>filter()</literal>."
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:670
#, no-c-format
msgid "<![CDATA[sortedUsers = s.createFilter( group.getUsers(), \"order by this.name\" ).list();]]>"
msgstr ""

#. Tag: title
#: collection_mapping.xml:675
#, no-c-format
msgid "Bidirectional associations"
msgstr ""

#. Tag: para
#: collection_mapping.xml:677
#, no-c-format
msgid "A <emphasis>bidirectional association</emphasis> allows navigation from both \"ends\" of the association. Two kinds of bidirectional association are supported:"
msgstr ""

#. Tag: term
#: collection_mapping.xml:684
#, no-c-format
msgid "one-to-many"
msgstr ""

#. Tag: para
#: collection_mapping.xml:686
#, no-c-format
msgid "set or bag valued at one end, single-valued at the other"
msgstr ""

#. Tag: term
#: collection_mapping.xml:692
#, no-c-format
msgid "many-to-many"
msgstr ""

#. Tag: para
#: collection_mapping.xml:694
#, no-c-format
msgid "set or bag valued at both ends"
msgstr ""

#. Tag: para
#: collection_mapping.xml:703
#, no-c-format
msgid "You may specify a bidirectional many-to-many association simply by mapping two many-to-many associations to the same database table and declaring one end as <emphasis>inverse</emphasis> (which one is your choice, but it can not be an indexed collection)."
msgstr ""

#. Tag: para
#: collection_mapping.xml:710
#, no-c-format
msgid "Here's an example of a bidirectional many-to-many association; each category can have many items and each item can be in many categories:"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:715
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"Category\">\n"
      "    <id name=\"id\" column=\"CATEGORY_ID\"/>\n"
      "    ...\n"
      "    <bag name=\"items\" table=\"CATEGORY_ITEM\">\n"
      "        <key column=\"CATEGORY_ID\"/>\n"
      "        <many-to-many class=\"Item\" column=\"ITEM_ID\"/>\n"
      "    </bag>\n"
      "</class>\n"
      "\n"
      "<class name=\"Item\">\n"
      "    <id name=\"id\" column=\"ITEM_ID\"/>\n"
      "    ...\n"
      "\n"
      "    <!-- inverse end -->\n"
      "    <bag name=\"categories\" table=\"CATEGORY_ITEM\" inverse=\"true\">\n"
      "        <key column=\"ITEM_ID\"/>\n"
      "        <many-to-many class=\"Category\" column=\"CATEGORY_ID\"/>\n"
      "    </bag>\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:717
#, no-c-format
msgid "Changes made only to the inverse end of the association are <emphasis>not</emphasis> persisted. This means that Hibernate has two representations in memory for every bidirectional association, one link from A to B and another link from B to A. This is easier to understand if you think about the Java object model and how we create a many-to-many relationship in Java:"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:725
#, no-c-format
msgid ""
      "<![CDATA[\n"
      "category.getItems().add(item);          // The category now \"knows\" about the relationship\n"
      "item.getCategories().add(category);     // The item now \"knows\" about the relationship\n"
      "\n"
      "session.persist(item);                   // The relationship won't be saved!\n"
      "session.persist(category);               // The relationship will be saved]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:727
#, no-c-format
msgid "The non-inverse side is used to save the in-memory representation to the database."
msgstr ""

#. Tag: para
#: collection_mapping.xml:731
#, no-c-format
msgid "You may define a bidirectional one-to-many association by mapping a one-to-many association to the same table column(s) as a many-to-one association and declaring the many-valued end <literal>inverse=\"true\"</literal>."
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:737
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"Parent\">\n"
      "    <id name=\"id\" column=\"parent_id\"/>\n"
      "    ....\n"
      "    <set name=\"children\" inverse=\"true\">\n"
      "        <key column=\"parent_id\"/>\n"
      "        <one-to-many class=\"Child\"/>\n"
      "    </set>\n"
      "</class>\n"
      "\n"
      "<class name=\"Child\">\n"
      "    <id name=\"id\" column=\"child_id\"/>\n"
      "    ....\n"
      "    <many-to-one name=\"parent\" \n"
      "        class=\"Parent\" \n"
      "        column=\"parent_id\"\n"
      "        not-null=\"true\"/>\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:739
#, no-c-format
msgid "Mapping one end of an association with <literal>inverse=\"true\"</literal> doesn't affect the operation of cascades, these are orthogonal concepts!"
msgstr ""

#. Tag: title
#: collection_mapping.xml:747
#, no-c-format
msgid "Bidirectional associations with indexed collections"
msgstr ""

#. Tag: para
#: collection_mapping.xml:748
#, no-c-format
msgid "A bidirectional association where one end is represented as a <literal>&lt;list&gt;</literal> or <literal>&lt;map&gt;</literal> requires special consideration. If there is a property of the child class which maps to the index column, no problem, we can continue using <literal>inverse=\"true\"</literal> on the collection mapping:"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:755
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"Parent\">\n"
      "    <id name=\"id\" column=\"parent_id\"/>\n"
      "    ....\n"
      "    <map name=\"children\" inverse=\"true\">\n"
      "        <key column=\"parent_id\"/>\n"
      "        <map-key column=\"name\" \n"
      "            type=\"string\"/>\n"
      "        <one-to-many class=\"Child\"/>\n"
      "    </map>\n"
      "</class>\n"
      "\n"
      "<class name=\"Child\">\n"
      "    <id name=\"id\" column=\"child_id\"/>\n"
      "    ....\n"
      "    <property name=\"name\" \n"
      "        not-null=\"true\"/>\n"
      "    <many-to-one name=\"parent\" \n"
      "        class=\"Parent\" \n"
      "        column=\"parent_id\"\n"
      "        not-null=\"true\"/>\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:757
#, no-c-format
msgid "But, if there is no such property on the child class, we can't think of the association as truly bidirectional (there is information available at one end of the association that is not available at the other end). In this case, we can't map the collection <literal>inverse=\"true\"</literal>. Instead, we could use the following mapping:"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:764
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"Parent\">\n"
      "    <id name=\"id\" column=\"parent_id\"/>\n"
      "    ....\n"
      "    <map name=\"children\">\n"
      "        <key column=\"parent_id\"\n"
      "            not-null=\"true\"/>\n"
      "        <map-key column=\"name\" \n"
      "            type=\"string\"/>\n"
      "        <one-to-many class=\"Child\"/>\n"
      "    </map>\n"
      "</class>\n"
      "\n"
      "<class name=\"Child\">\n"
      "    <id name=\"id\" column=\"child_id\"/>\n"
      "    ....\n"
      "    <many-to-one name=\"parent\" \n"
      "        class=\"Parent\" \n"
      "        column=\"parent_id\"\n"
      "        insert=\"false\"\n"
      "        update=\"false\"\n"
      "        not-null=\"true\"/>\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: collection_mapping.xml:766
#, no-c-format
msgid "Note that in this mapping, the collection-valued end of the association is responsible for updates to the foreign key. TODO: Does this really result in some unnecessary update statements?"
msgstr ""

#. Tag: title
#: collection_mapping.xml:774
#, no-c-format
msgid "Ternary associations"
msgstr ""

#. Tag: para
#: collection_mapping.xml:776
#, no-c-format
msgid "There are three possible approaches to mapping a ternary association. One is to use a <literal>Map</literal> with an association as its index:"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:781
#, no-c-format
msgid ""
      "<![CDATA[<map name=\"contracts\">\n"
      "    <key column=\"employer_id\" not-null=\"true\"/>\n"
      "    <map-key-many-to-many column=\"employee_id\" class=\"Employee\"/>\n"
      "    <one-to-many class=\"Contract\"/>\n"
      "</map>]]>"
msgstr ""

#. Tag: programlisting
#: collection_mapping.xml:783
#, no-c-format