INT-3322 JDBC i-c-a SpEL Select ParameterSource
JIRA: https://jira.spring.io/browse/INT-3322 Support the use of an ExpressionEvaluatingSqlParameterSource from the ExpressionEvaluatingSqlParameterSourceFactory as the `select-sql-parameter-source` for an inbound channel adapter. Add documentation showing how to construct the bean. Add a mechanism to disable caching so that the expression is re-evaluated each time. However, the value should still be cached between the `hasValue()` and `getValue()` calls. INT-3322 Polishing; PR Comments
This commit is contained in:
Gary russell
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Artem Bilan
Artem Bilan
parent
98b46c61f3
commit
c73cc40e23
@@ -74,12 +74,65 @@
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channel="target" data-source="dataSource"
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update="update item set status=10 where id in (:id)" />]]></programlisting>
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<note>
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The parameters in the update query are specified with a colon (:) prefix to the name of a parameter (which in this case is an expression to be applied to each of the rows in the polled result set). This is a standard feature of the named parameter JDBC support in Spring JDBC combined with a convention (projection onto the polled result list) adopted in Spring Integration. The underlying Spring JDBC features limit the available expressions (e.g. most special characters other than period are disallowed), but since the target is usually a list of or an individual object addressable by simple bean paths this isn't unduly restrictive.
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</note> To change the parameter generation strategy you can inject a
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The parameters in the update query are specified with a colon (:)
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prefix to the name of a parameter (which in this case is an expression
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to be applied to each of the rows in the polled result set).
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This is a standard feature of the named parameter JDBC support in Spring JDBC
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combined with a convention (projection onto the polled result list)
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adopted in Spring Integration.
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The underlying Spring JDBC features limit the available expressions
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(e.g. most special characters other than period are disallowed),
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but since the target is usually a list of or an individual object addressable by simple bean paths this isn't unduly restrictive.
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</note>
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To change the parameter generation strategy you can inject a
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<classname>SqlParameterSourceFactory</classname> into the adapter to
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override the default behavior (the adapter has a
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<code>sql-parameter-source-factory</code> attribute).</para>
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<code>sql-parameter-source-factory</code> attribute). Spring Integration
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provides a <classname>ExpressionEvaluatingSqlParameterSourceFactory</classname> which
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will create a SpEL-based parameter source, with the results of the query as the
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<code>#root</code> object. (If <code>update-per-row</code> is true, the root object
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is the row). If the same parameter name appears multiple times in the update query, it
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is evaluated only one time, and its result is cached.
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</para>
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<para>
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You can also use a parameter source for the select query. In this case, since there is no "result"
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object to evaluate against, a single parameter source is used each time (rather than using a
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parameter source factory). Starting with <emphasis>version 4.0</emphasis>, you can use Spring
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to create a SpEL based parameter source as follows:
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</para>
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<programlisting language="xml"><![CDATA[<int-jdbc:inbound-channel-adapter query="select * from item where status=:status"
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channel="target" data-source="dataSource"
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select-sql-parameter-source="parameterSource" />
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<bean id="parameterSource" factory-bean="parameterSourceFactory"
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factory-method="createParameterSourceNoCache">
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<constructor-arg value="" />
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</bean>
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<bean id="parameterSourceFactory"
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class="o.s.integration.jdbc.ExpressionEvaluatingSqlParameterSourceFactory">
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<property name="parameterExpressions">
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<map>
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<entry key="status" value="@statusBean.which()" />
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</map>
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</property>
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</bean>
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<bean id="statusBean" class="foo.StatusDetermination" />]]></programlisting>
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<para>
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The <code>value</code> in each parameter expression can be any valid SpEL expression.
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The <code>#root</code> object for the expression evaluation is the
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constructor argument defined on the <code>parameterSource</code> bean. It is static
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for all evaluations (in this case, an empty String).
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</para>
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<important>
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Use the <code>createParameterSourceNoCache</code> factory method; otherwise the parameter source will
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cache the result of the evaluation. Also note that, because caching is disabled, if the same
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parameter name appears in the select query multiple times, it will be re-evaluated for each
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occurrence.
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</important>
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<section>
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<title>Polling and Transactions</title>
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@@ -355,7 +408,7 @@
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For more information, please see:
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</para>
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<para>
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<ulink url="http://dev.mysql.com/doc/refman/5.6/en/fractional-seconds.html"></ulink>
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<ulink url="http://dev.mysql.com/doc/refman/5.6/en/fractional-seconds.html"/>
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</para>
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<para>
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Also important, please ensure that you use an up-to-date version
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