inheritance_mapping.pot

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

#. Tag: para
#: inheritance_mapping.xml:194
#, no-c-format
msgid "The limitation of this approach is that if a property is mapped on the superclass, the column name must be the same on all subclass tables. (We might relax this in a future release of Hibernate.) The identity generator strategy is not allowed in union subclass inheritance, indeed the primary key seed has to be shared accross all unioned subclasses of a hierarchy."
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:203
#, no-c-format
msgid "If your superclass is abstract, map it with <literal>abstract=\"true\"</literal>. Of course, if it is not abstract, an additional table (defaults to <literal>PAYMENT</literal> in the example above) is needed to hold instances of the superclass."
msgstr ""

#. Tag: title
#: inheritance_mapping.xml:213
#, no-c-format
msgid "Table per concrete class, using implicit polymorphism"
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:215
#, no-c-format
msgid "An alternative approach is to make use of implicit polymorphism:"
msgstr ""

#. Tag: programlisting
#: inheritance_mapping.xml:219
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"CreditCardPayment\" table=\"CREDIT_PAYMENT\">\n"
      "    <id name=\"id\" type=\"long\" column=\"CREDIT_PAYMENT_ID\">\n"
      "        <generator class=\"native\"/>\n"
      "    </id>\n"
      "    <property name=\"amount\" column=\"CREDIT_AMOUNT\"/>\n"
      "    ...\n"
      "</class>\n"
      "\n"
      "<class name=\"CashPayment\" table=\"CASH_PAYMENT\">\n"
      "    <id name=\"id\" type=\"long\" column=\"CASH_PAYMENT_ID\">\n"
      "        <generator class=\"native\"/>\n"
      "    </id>\n"
      "    <property name=\"amount\" column=\"CASH_AMOUNT\"/>\n"
      "    ...\n"
      "</class>\n"
      "\n"
      "<class name=\"ChequePayment\" table=\"CHEQUE_PAYMENT\">\n"
      "    <id name=\"id\" type=\"long\" column=\"CHEQUE_PAYMENT_ID\">\n"
      "        <generator class=\"native\"/>\n"
      "    </id>\n"
      "    <property name=\"amount\" column=\"CHEQUE_AMOUNT\"/>\n"
      "    ...\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:221
#, no-c-format
msgid "Notice that nowhere do we mention the <literal>Payment</literal> interface explicitly. Also notice that properties of <literal>Payment</literal> are mapped in each of the subclasses. If you want to avoid duplication, consider using XML entities (e.g. <literal>[ &lt;!ENTITY allproperties SYSTEM \"allproperties.xml\"&gt; ]</literal> in the <literal>DOCTYPE</literal> declartion and <literal>&amp;allproperties;</literal> in the mapping)."
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:231
#, no-c-format
msgid "The disadvantage of this approach is that Hibernate does not generate SQL <literal>UNION</literal>s when performing polymorphic queries."
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:236
#, no-c-format
msgid "For this mapping strategy, a polymorphic association to <literal>Payment</literal> is usually mapped using <literal>&lt;any&gt;</literal>."
msgstr ""

#. Tag: programlisting
#: inheritance_mapping.xml:241
#, no-c-format
msgid ""
      "<![CDATA[<any name=\"payment\" meta-type=\"string\" id-type=\"long\">\n"
      "    <meta-value value=\"CREDIT\" class=\"CreditCardPayment\"/>\n"
      "    <meta-value value=\"CASH\" class=\"CashPayment\"/>\n"
      "    <meta-value value=\"CHEQUE\" class=\"ChequePayment\"/>\n"
      "    <column name=\"PAYMENT_CLASS\"/>\n"
      "    <column name=\"PAYMENT_ID\"/>\n"
      "</any>]]>"
msgstr ""

#. Tag: title
#: inheritance_mapping.xml:246
#, no-c-format
msgid "Mixing implicit polymorphism with other inheritance mappings"
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:248
#, no-c-format
msgid "There is one further thing to notice about this mapping. Since the subclasses are each mapped in their own <literal>&lt;class&gt;</literal> element (and since <literal>Payment</literal> is just an interface), each of the subclasses could easily be part of another inheritance hierarchy! (And you can still use polymorphic queries against the <literal>Payment</literal> interface.)"
msgstr ""

#. Tag: programlisting
#: inheritance_mapping.xml:256
#, no-c-format
msgid ""
      "<![CDATA[<class name=\"CreditCardPayment\" table=\"CREDIT_PAYMENT\">\n"
      "    <id name=\"id\" type=\"long\" column=\"CREDIT_PAYMENT_ID\">\n"
      "        <generator class=\"native\"/>\n"
      "    </id>\n"
      "    <discriminator column=\"CREDIT_CARD\" type=\"string\"/>\n"
      "    <property name=\"amount\" column=\"CREDIT_AMOUNT\"/>\n"
      "    ...\n"
      "    <subclass name=\"MasterCardPayment\" discriminator-value=\"MDC\"/>\n"
      "    <subclass name=\"VisaPayment\" discriminator-value=\"VISA\"/>\n"
      "</class>\n"
      "\n"
      "<class name=\"NonelectronicTransaction\" table=\"NONELECTRONIC_TXN\">\n"
      "    <id name=\"id\" type=\"long\" column=\"TXN_ID\">\n"
      "        <generator class=\"native\"/>\n"
      "    </id>\n"
      "    ...\n"
      "    <joined-subclass name=\"CashPayment\" table=\"CASH_PAYMENT\">\n"
      "        <key column=\"PAYMENT_ID\"/>\n"
      "        <property name=\"amount\" column=\"CASH_AMOUNT\"/>\n"
      "        ...\n"
      "    </joined-subclass>\n"
      "    <joined-subclass name=\"ChequePayment\" table=\"CHEQUE_PAYMENT\">\n"
      "        <key column=\"PAYMENT_ID\"/>\n"
      "        <property name=\"amount\" column=\"CHEQUE_AMOUNT\"/>\n"
      "        ...\n"
      "    </joined-subclass>\n"
      "</class>]]>"
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:258
#, no-c-format
msgid "Once again, we don't mention <literal>Payment</literal> explicitly. If we execute a query against the <literal>Payment</literal> interface - for example, <literal>from Payment</literal> - Hibernate automatically returns instances of <literal>CreditCardPayment</literal> (and its subclasses, since they also implement <literal>Payment</literal>), <literal>CashPayment</literal> and <literal>ChequePayment</literal> but not instances of <literal>NonelectronicTransaction</literal>."
msgstr ""

#. Tag: title
#: inheritance_mapping.xml:273
#, no-c-format
msgid "Limitations"
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:275
#, no-c-format
msgid "There are certain limitations to the \"implicit polymorphism\" approach to the table per concrete-class mapping strategy. There are somewhat less restrictive limitations to <literal>&lt;union-subclass&gt;</literal> mappings."
msgstr ""

#. Tag: para
#: inheritance_mapping.xml:282
#, no-c-format
msgid "The following table shows the limitations of table per concrete-class mappings, and of implicit polymorphism, in Hibernate."
msgstr ""

#. Tag: title
#: inheritance_mapping.xml:288
#, no-c-format
msgid "Features of inheritance mappings"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:300
#, no-c-format
msgid "Inheritance strategy"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:301
#, no-c-format
msgid "Polymorphic many-to-one"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:302
#, no-c-format
msgid "Polymorphic one-to-one"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:303
#, no-c-format
msgid "Polymorphic one-to-many"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:304
#, no-c-format
msgid "Polymorphic many-to-many"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:305
#, no-c-format
msgid "Polymorphic <literal>load()/get()</literal>"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:306
#, no-c-format
msgid "Polymorphic queries"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:307
#, no-c-format
msgid "Polymorphic joins"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:308
#, no-c-format
msgid "Outer join fetching"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:313
#, no-c-format
msgid "table per class-hierarchy"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:314 inheritance_mapping.xml:325 inheritance_mapping.xml:336
#, no-c-format
msgid "&lt;many-to-one&gt;"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:315 inheritance_mapping.xml:326 inheritance_mapping.xml:337
#, no-c-format
msgid "&lt;one-to-one&gt;"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:316 inheritance_mapping.xml:327
#, no-c-format
msgid "&lt;one-to-many&gt;"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:317 inheritance_mapping.xml:328 inheritance_mapping.xml:339
#, no-c-format
msgid "&lt;many-to-many&gt;"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:318 inheritance_mapping.xml:329 inheritance_mapping.xml:340
#, no-c-format
msgid "s.get(Payment.class, id)"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:319 inheritance_mapping.xml:330 inheritance_mapping.xml:341 inheritance_mapping.xml:352
#, no-c-format
msgid "from Payment p"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:320 inheritance_mapping.xml:331 inheritance_mapping.xml:342
#, no-c-format
msgid "from Order o join o.payment p"
msgstr ""

#. Tag: emphasis
#: inheritance_mapping.xml:321 inheritance_mapping.xml:332 inheritance_mapping.xml:343
#, no-c-format
msgid "supported"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:324
#, no-c-format
msgid "<entry>table per subclass</entry>"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:335
#, no-c-format
msgid "table per concrete-class (union-subclass)"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:338
#, no-c-format
msgid "<literal>&lt;one-to-many&gt;</literal> (for <literal>inverse=\"true\"</literal> only)"
msgstr ""

#. Tag: entry
#: inheritance_mapping.xml:346
#, no-c-format
msgid "table per concrete class (implicit polymorphism)"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:347
#, no-c-format
msgid "&lt;any&gt;"
msgstr ""

#. Tag: emphasis
#: inheritance_mapping.xml:348 inheritance_mapping.xml:349 inheritance_mapping.xml:353 inheritance_mapping.xml:354
#, no-c-format
msgid "not supported"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:350
#, no-c-format
msgid "&lt;many-to-any&gt;"
msgstr ""

#. Tag: literal
#: inheritance_mapping.xml:351
#, no-c-format
msgid "s.createCriteria(Payment.class).add( Restrictions.idEq(id) ).uniqueResult()"
msgstr ""