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java.lang.Object org.apache.openjpa.jdbc.kernel.exps.GetColumn
public class GetColumn
Returns the SQL alias of the named column for use in a query. Note that
to retrieve columns in the table of the candidate object, you must
explicitly qualify the extension with this
, as demonstrated
in the second example below.
Examples:
"company.address.ext:getColumn (\"ID\") == 5"
"this.ext:getColumn (\"CLS\") == \"org.apache.openjpa.example.Person\""
Field Summary | |
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static String |
TAG
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Constructor Summary | |
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GetColumn()
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Method Summary | |
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void |
appendTo(SQLBuffer buf,
FilterValue target,
FilterValue[] args,
ClassMapping type,
JDBCStore store)
Append the SQL for this expression or value. |
Object |
evaluate(Object target,
Class targetClass,
Object[] args,
Class[] argClasses,
Object candidate,
StoreContext ctx)
Evaluate the given expression. |
boolean |
expectsArguments()
Return true if this extension expects arguments to act on. |
boolean |
expectsTarget()
Return true if this extension expects a target to act on. |
String |
getTag()
Return the tag that this extension listens for. |
Class |
getType(Class targetClass,
Class[] argClasses)
Return the expected type of the result of this listener. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final String TAG
Constructor Detail |
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public GetColumn()
Method Detail |
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public String getTag()
FilterListener
getTag
in interface FilterListener
public boolean expectsArguments()
FilterListener
field.ext:toUpperCase ()
.
expectsArguments
in interface FilterListener
public boolean expectsTarget()
FilterListener
field.ext:toUpperCase ()
acts on the target
field
but has no arguments, while another possible form,
ext:toUpperCase (field)
has no target but does have an
argument.
expectsTarget
in interface FilterListener
public Object evaluate(Object target, Class targetClass, Object[] args, Class[] argClasses, Object candidate, StoreContext ctx)
FilterListener
evaluate
in interface FilterListener
target
- the target object / field value to act on; will be
null if this extension does not expect a targettargetClass
- the expected class of the target; given in case
the target evaluates to null and typing is neededargs
- the values of the arguments given in the filter;
will be null if this extension does not expect an argumentargClasses
- the expected classes of the arguments; given in case
an argument evaluates to null and typing is neededcandidate
- the candidate object being evaluatedctx
- the persistence context
Boolean.TRUE
or Boolean.FALSE
public void appendTo(SQLBuffer buf, FilterValue target, FilterValue[] args, ClassMapping type, JDBCStore store)
JDBCFilterListener
appendTo
in interface JDBCFilterListener
buf
- the SQL buffer to append totarget
- the target to act on, or null if the listener
doesn't expect a targetargs
- the values of the arguments given in the filter, or
null if this listener doesn't expect argumentstype
- the class mapping for the query's candidate classstore
- the store that owns the querypublic Class getType(Class targetClass, Class[] argClasses)
FilterListener
getType
in interface FilterListener
targetClass
- the expected class of the target, or null if no targetargClasses
- the expected classes of the arguments, or null if
no arguments
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