example_parentchild.po

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#, no-c-format
msgid "And now, only one SQL <literal>INSERT</literal> would be issued!"
msgstr "And now, only one SQL <literal>INSERT</literal> would be issued!"

#. Tag: para
#: example_parentchild.xml:136
#, no-c-format
msgid ""
"To tighten things up a bit, we could create an <literal>addChild()</literal> "
"method of <literal>Parent</literal>."
msgstr ""
"To tighten things up a bit, we could create an <literal>addChild()</literal> "
"method of <literal>Parent</literal>."

#. Tag: programlisting
#: example_parentchild.xml:141
#, no-c-format
msgid ""
"<![CDATA[public void addChild(Child c) {\n"
"    c.setParent(this);\n"
"    children.add(c);\n"
"}]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:143
#, no-c-format
msgid "Now, the code to add a <literal>Child</literal> looks like"
msgstr "Now, the code to add a <literal>Child</literal> looks like"

#. Tag: programlisting
#: example_parentchild.xml:147
#, no-c-format
msgid ""
"<![CDATA[Parent p = (Parent) session.load(Parent.class, pid);\n"
"Child c = new Child();\n"
"p.addChild(c);\n"
"session.save(c);\n"
"session.flush();]]>"
msgstr ""

#. Tag: title
#: example_parentchild.xml:152
#, no-c-format
msgid "Cascading life cycle"
msgstr "Cascading life cycle"

#. Tag: para
#: example_parentchild.xml:154
#, no-c-format
msgid ""
"The explicit call to <literal>save()</literal> is still annoying. We will "
"address this by using cascades."
msgstr ""
"The explicit call to <literal>save()</literal> is still annoying. We will "
"address this by using cascades."

#. Tag: programlisting
#: example_parentchild.xml:159
#, no-c-format
msgid ""
"<![CDATA[<set name=\"children\" inverse=\"true\" cascade=\"all\">\n"
"    <key column=\"parent_id\"/>\n"
"    <one-to-many class=\"Child\"/>\n"
"</set>]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:161
#, no-c-format
msgid "This simplifies the code above to"
msgstr "This simplifies the code above to"

#. Tag: programlisting
#: example_parentchild.xml:165
#, no-c-format
msgid ""
"<![CDATA[Parent p = (Parent) session.load(Parent.class, pid);\n"
"Child c = new Child();\n"
"p.addChild(c);\n"
"session.flush();]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:167
#, no-c-format
msgid ""
"Similarly, we don't need to iterate over the children when saving or "
"deleting a <literal>Parent</literal>. The following removes <literal>p</"
"literal> and all its children from the database."
msgstr ""
"Similarly, we don't need to iterate over the children when saving or "
"deleting a <literal>Parent</literal>. The following removes <literal>p</"
"literal> and all its children from the database."

#. Tag: programlisting
#: example_parentchild.xml:172
#, no-c-format
msgid ""
"<![CDATA[Parent p = (Parent) session.load(Parent.class, pid);\n"
"session.delete(p);\n"
"session.flush();]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:174
#, no-c-format
msgid "However, this code"
msgstr "However, this code"

#. Tag: programlisting
#: example_parentchild.xml:178
#, no-c-format
msgid ""
"<![CDATA[Parent p = (Parent) session.load(Parent.class, pid);\n"
"Child c = (Child) p.getChildren().iterator().next();\n"
"p.getChildren().remove(c);\n"
"c.setParent(null);\n"
"session.flush();]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:180
#, no-c-format
msgid ""
"will not remove <literal>c</literal> from the database; it will ony remove "
"the link to <literal>p</literal> (and cause a <literal>NOT NULL</literal> "
"constraint violation, in this case). You need to explicitly <literal>delete()"
"</literal> the <literal>Child</literal>."
msgstr ""
"will not remove <literal>c</literal> from the database; it will ony remove "
"the link to <literal>p</literal> (and cause a <literal>NOT NULL</literal> "
"constraint violation, in this case). You need to explicitly <literal>delete()"
"</literal> the <literal>Child</literal>."

#. Tag: programlisting
#: example_parentchild.xml:186
#, no-c-format
msgid ""
"<![CDATA[Parent p = (Parent) session.load(Parent.class, pid);\n"
"Child c = (Child) p.getChildren().iterator().next();\n"
"p.getChildren().remove(c);\n"
"session.delete(c);\n"
"session.flush();]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:188
#, no-c-format
msgid ""
"Now, in our case, a <literal>Child</literal> can't really exist without its "
"parent. So if we remove a <literal>Child</literal> from the collection, we "
"really do want it to be deleted. For this, we must use <literal>cascade="
"\"all-delete-orphan\"</literal>."
msgstr ""
"Now, in our case, a <literal>Child</literal> can't really exist without its "
"parent. So if we remove a <literal>Child</literal> from the collection, we "
"really do want it to be deleted. For this, we must use <literal>cascade="
"\"all-delete-orphan\"</literal>."

#. Tag: programlisting
#: example_parentchild.xml:194
#, no-c-format
msgid ""
"<![CDATA[<set name=\"children\" inverse=\"true\" cascade=\"all-delete-orphan"
"\">\n"
"    <key column=\"parent_id\"/>\n"
"    <one-to-many class=\"Child\"/>\n"
"</set>]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:196
#, no-c-format
msgid ""
"Note: even though the collection mapping specifies <literal>inverse=\"true"
"\"</literal>, cascades are still processed by iterating the collection "
"elements. So if you require that an object be saved, deleted or updated by "
"cascade, you must add it to the collection. It is not enough to simply call "
"<literal>setParent()</literal>."
msgstr ""
"Note: even though the collection mapping specifies <literal>inverse=\"true"
"\"</literal>, cascades are still processed by iterating the collection "
"elements. So if you require that an object be saved, deleted or updated by "
"cascade, you must add it to the collection. It is not enough to simply call "
"<literal>setParent()</literal>."

#. Tag: title
#: example_parentchild.xml:206
#, no-c-format
msgid "Cascades and <literal>unsaved-value</literal>"
msgstr "Cascades and <literal>unsaved-value</literal>"

#. Tag: para
#: example_parentchild.xml:208
#, no-c-format
msgid ""
"Suppose we loaded up a <literal>Parent</literal> in one <literal>Session</"
"literal>, made some changes in a UI action and wish to persist these changes "
"in a new session by calling <literal>update()</literal>. The "
"<literal>Parent</literal> will contain a collection of childen and, since "
"cascading update is enabled, Hibernate needs to know which children are "
"newly instantiated and which represent existing rows in the database. Lets "
"assume that both <literal>Parent</literal> and <literal>Child</literal> have "
"genenerated identifier properties of type <literal>Long</literal>. Hibernate "
"will use the identifier and version/timestamp property value to determine "
"which of the children are new. (See <xref linkend=\"objectstate-saveorupdate"
"\"/>.) <emphasis>In Hibernate3, it is no longer necessary to specify an "
"<literal>unsaved-value</literal> explicitly.</emphasis>"
msgstr ""
"Suppose we loaded up a <literal>Parent</literal> in one <literal>Session</"
"literal>, made some changes in a UI action and wish to persist these changes "
"in a new session by calling <literal>update()</literal>. The "
"<literal>Parent</literal> will contain a collection of childen and, since "
"cascading update is enabled, Hibernate needs to know which children are "
"newly instantiated and which represent existing rows in the database. Lets "
"assume that both <literal>Parent</literal> and <literal>Child</literal> have "
"genenerated identifier properties of type <literal>Long</literal>. Hibernate "
"will use the identifier and version/timestamp property value to determine "
"which of the children are new. (See <xref linkend=\"objectstate-saveorupdate"
"\"/>.) <emphasis>In Hibernate3, it is no longer necessary to specify an "
"<literal>unsaved-value</literal> explicitly.</emphasis>"

#. Tag: para
#: example_parentchild.xml:220
#, no-c-format
msgid ""
"The following code will update <literal>parent</literal> and <literal>child</"
"literal> and insert <literal>newChild</literal>."
msgstr ""
"The following code will update <literal>parent</literal> and <literal>child</"
"literal> and insert <literal>newChild</literal>."

#. Tag: programlisting
#: example_parentchild.xml:225
#, no-c-format
msgid ""
"<![CDATA[//parent and child were both loaded in a previous session\n"
"parent.addChild(child);\n"
"Child newChild = new Child();\n"
"parent.addChild(newChild);\n"
"session.update(parent);\n"
"session.flush();]]>"
msgstr ""

#. Tag: para
#: example_parentchild.xml:227
#, no-c-format
msgid ""
"Well, that's all very well for the case of a generated identifier, but what "
"about assigned identifiers and composite identifiers? This is more "
"difficult, since Hibernate can't use the identifier property to distinguish "
"between a newly instantiated object (with an identifier assigned by the "
"user) and an object loaded in a previous session. In this case, Hibernate "
"will either use the timestamp or version property, or will actually query "
"the second-level cache or, worst case, the database, to see if the row "
"exists."
msgstr ""
"Well, that's all very well for the case of a generated identifier, but what "
"about assigned identifiers and composite identifiers? This is more "
"difficult, since Hibernate can't use the identifier property to distinguish "
"between a newly instantiated object (with an identifier assigned by the "
"user) and an object loaded in a previous session. In this case, Hibernate "
"will either use the timestamp or version property, or will actually query "
"the second-level cache or, worst case, the database, to see if the row "
"exists."

#. Tag: title
#: example_parentchild.xml:260
#, no-c-format
msgid "Conclusion"
msgstr "Conclusion"

#. Tag: para
#: example_parentchild.xml:262
#, no-c-format
msgid ""
"There is quite a bit to digest here and it might look confusing first time "
"around. However, in practice, it all works out very nicely. Most Hibernate "
"applications use the parent / child pattern in many places."
msgstr ""
"There is quite a bit to digest here and it might look confusing first time "
"around. However, in practice, it all works out very nicely. Most Hibernate "
"applications use the parent / child pattern in many places."

#. Tag: para
#: example_parentchild.xml:267
#, no-c-format
msgid ""
"We mentioned an alternative in the first paragraph. None of the above issues "
"exist in the case of <literal>&lt;composite-element&gt;</literal> mappings, "
"which have exactly the semantics of a parent / child relationship. "
"Unfortunately, there are two big limitations to composite element classes: "
"composite elements may not own collections, and they should not be the child "
"of any entity other than the unique parent."
msgstr ""
"We mentioned an alternative in the first paragraph. None of the above issues "
"exist in the case of <literal>&lt;composite-element&gt;</literal> mappings, "
"which have exactly the semantics of a parent / child relationship. "
"Unfortunately, there are two big limitations to composite element classes: "
"composite elements may not own collections, and they should not be the child "
"of any entity other than the unique parent."