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/*
* RetrieveDesc.java
*
* Created on March 3, 2000
*/
package com.sun.jdo.spi.persistence.support.sqlstore;
/**
* <P>This interface represents a retrieve descriptor used by an application
* to retrieve container-managed entity beans from a persistent store. It
* allows you specify which persistent fields an application wants to retrieve.
* In addition, it allows an application to specify sophisticated constraints
* on its object retrieval.
*/
public interface RetrieveDesc extends ActionDesc {
/**
* The addResult method is used to specify which fields should be
* returned in a persistent object. If the field requested is a
* reference to another persistent object then a RetrieveDesc may be
* provided which describes which fields of the referenced object
* should be returned and, optionally, constraints on it.
* The parameter <code>projection</code> specifies, if the field
* specified by <code>name</code> should be projected.
*
* @param name The name of the field to return.
* @param foreignConstraint
* RetrieveDesc describing fields and constraints for a referenced object.
* @param projection Specifies, if this is a projection.
*/
public void addResult(String name, RetrieveDesc foreignConstraint, boolean projection);
/**
* The addResult method can be used to specify <it>global</it>
* query attributes that don't end up in the where clause.
* Aggregate functions and the distinct op code are examples for
* those query options. The result type defines the object to be
* returned by an aggregate query. In case of distinct the result
* type should be FieldTypeEnumeration.NOT_ENUMERATED. The method
* might be called twice, in case of a JDOQL query having both an
* aggregate and distinct:
* query.setResult("avg (distinct salary)");
* ->
* retrieveDesc.addResult(OP_AVG, FieldTypeEnumeration.DOUBLE);
* retrieveDesc.addResult(OP_DISTINCT, FieldTypeEnumeration.NOT_ENUMERATED);
* retrieveDesc.addResult("salary", null, true);
*
* @param opCode The operation code.
* @param resultType The object type returned by aggregate queries.
* @see com.sun.jdo.spi.persistence.utility.FieldTypeEnumeration
*/
public void addResult(int opCode, int resultType);
/**
* <P>Adds a constraint on the persistent field specified by
* <code>name</code>. The valid values for <code>operation
* </code> are defined in <b>ActionDesc</b>. The parameter
* <code>value</code> specifies the constraint value.
* <P>By default, multiple constraints are implicitly ANDed together.
* If the applications want to OR together the constraints,
* it can explicitly add <b>OP_OR</b> constraints. For example,
* to OR together two constraints, an application can do the following:
* <PRE>
* addConstraint("field1", ActionDesc.OP_EQ, "field1Value");
* addConstraint("field2", ActionDesc.OP_EQ, "field2Value");
* addConstraint(null, ActionDesc.OP_OR, null);
* </PRE>
* <P>The important thing to note about the above example is
* that the constraints are processed in postfix order, so
* the above example should be read as
* <PRE>
* (field1 == "field1Value") OR (field2 == "field2Value")
* </PRE>
*/
public void addConstraint(String name, int operation, Object value);
/**
* <P>Adds a constraint on the foreign field specified by
* <code>name</code>. This method is used to specify a relationship
* navigation on field <code>name</code> to the class represented by
* the retrieve descriptor <code>foreignConstraint</code>.
* If <code>name</code> is null, an unrelated constraint is added.
* A constraint is unrelated, if there is neither a foreign field
* nor a local field connecting to the retrieve descriptor
* <code>foreignConstraint</code>.
*/
void addConstraint(String name, RetrieveDesc foreignConstraint);
/**
* <P>Adds a constraint on the field specified by <code>name</code>.
* This method is useful e.g. for comparisons of local fields with field of a related object:
* emp.addConstraint("lastName", ActionDesc.OP_EQ, mgr, lastName");
* compares the employee's lastName field with the lastName field of the related manager.
*/
void addConstraint(String name, int operator, RetrieveDesc foreignConstraint, String foreignFieldName);
/**
* Sets a navigational id on the retrieve descriptor.
* This id will be used to discriminate different retrieve descriptors which
* use the same navigational field.
*/
void setNavigationalId(Object navigationalId);
/** Sets the prefetchEnabled option.
*
* The prefetchEnabled option specifies whether prefetch of relationship
* fields should be enabled for this retrieve descriptor. The prefetch
* is enabled by default if such fields are part of DFG. A user needs
* to explicitely disable prefetch for any particular query if the related
* instances will not be used in this transaction.
*
* @param prefetchEnabled the setting of the prefetchEnabled option.
*/
void setPrefetchEnabled(boolean prefetchEnabled);
}