org.datanucleus.query
Class QueryUtils

java.lang.Object
  org.datanucleus.query.QueryUtils

public class QueryUtils
extends java.lang.Object

Utilities for use in queries.

Field Summary

protected static java.lang.Class[]	classArrayObjectObject Convenience Class[] for parameter types in getMethod call.
protected static Localiser	LOCALISER Localiser for messages.

Constructor Summary

QueryUtils()

Method Summary

static boolean	compareExpressionValues(java.lang.Object left, java.lang.Object right, Expression.Operator op) Convenience method to compare two expression values against the specified operator.
static java.lang.Object	createResultObjectUsingArgumentedConstructor(java.lang.Class resultClass, java.lang.Object[] fieldValues, java.lang.Class[] fieldTypes) Convenience method to create an instance of the result class with the provided field values, using a constructor taking the arguments.
static java.lang.Object	createResultObjectUsingDefaultConstructorAndSetters(java.lang.Class resultClass, java.lang.String[] resultFieldNames, java.lang.reflect.Field[] resultFields, java.lang.Object[] fieldValues) Convenience method to create an instance of the result class with the provided field values, using the default constructor and setting the fields using either public fields, or setters, or a put method.
static java.lang.Object	createResultObjectUsingDefaultConstructorAndSetters(java.lang.Class resultClass, java.lang.String[] resultFieldNames, java.util.Map resultClassFieldNames, java.lang.Object[] fieldValues) Convenience method to create an instance of the result class with the provided field values, using the default constructor and setting the fields using either public fields, or setters, or a put method.
static boolean	expressionHasNotOperator(Expression expr) Convenience method to return if there is a NOT operator in the expression.
static boolean	expressionHasOrOperator(Expression expr) Convenience method to return if there is an OR operator in the expression.
static java.lang.String[]	getExpressionsFromString(java.lang.String str) Convenience method to split an expression string into its constituent parts where separated by commas.
static java.lang.String	getKeyForQueryResultsCache(Query query, java.util.Map params) Convenience method to generate the "key" for storing the query results of a query with parameters.
static ParameterExpression	getParameterExpressionForPosition(Expression rootExpr, int pos) Convenience method to return the ParameterExpression for the specified position if found in the expression tree starting at
static java.lang.reflect.Method	getPublicPutMethodForResultClass(java.lang.Class resultClass) Convenience method to return the put(Object, Object method for the result class.
static java.lang.reflect.Method	getPublicSetMethodForFieldOfResultClass(java.lang.Class resultClass, java.lang.String fieldName, java.lang.Class fieldType) Convenience method to return the setXXX method for a field of the result class.
static java.lang.String	getStringValue(java.lang.Object obj) Convenience method to get the String value for an Object.
static java.lang.String	getStringValueForExpression(Expression expr, java.util.Map parameters) Convenience method to get the String value for an Expression.
static java.lang.Object	getValueForParameterExpression(java.util.Map parameterValues, ParameterExpression paramExpr) Convenience method to get the value for a ParameterExpression.
static boolean	queryParameterTypesAreCompatible(java.lang.Class cls1, java.lang.Class cls2)
static boolean	queryReturnsSingleRow(Query query) Convenience method to return whether the query should return a single row.
static boolean	resultClassIsSimple(java.lang.String className) Utility to return if the passed result class is a simple type with a single value.
static boolean	resultClassIsUserType(java.lang.String className) Utility to return if the passed result class is a user-type, and so requires fields matching up.
static boolean	resultHasOnlyAggregates(java.lang.String result) Convenience method to return if the "result" clause from a java string-based query language includes only aggregates.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOCALISER

protected static final Localiser LOCALISER

Localiser for messages.

classArrayObjectObject

protected static java.lang.Class[] classArrayObjectObject

Convenience Class[] for parameter types in getMethod call.

Constructor Detail

QueryUtils

public QueryUtils()

Method Detail

resultClassIsUserType

public static boolean resultClassIsUserType(java.lang.String className)

Utility to return if the passed result class is a user-type, and so requires fields matching up.

Parameters:

className - the class name looked for

Returns:

Whether it is a user class

resultClassIsSimple

public static boolean resultClassIsSimple(java.lang.String className)

Utility to return if the passed result class is a simple type with a single value. Checks the class name against the supported "simple" JDOQL result-class types.

Parameters:

className - the class name looked for

Returns:

Whether the result class is "simple".

resultHasOnlyAggregates

public static boolean resultHasOnlyAggregates(java.lang.String result)

Convenience method to return if the "result" clause from a java string-based query language includes only aggregates. This provides useful information when determining if the results will be a single row.

Parameters:

result - The result required

Returns:

Whether it has only aggregates

queryReturnsSingleRow

public static boolean queryReturnsSingleRow(Query query)

Convenience method to return whether the query should return a single row.

Returns:

Whether it represents a unique row

createResultObjectUsingArgumentedConstructor

public static java.lang.Object createResultObjectUsingArgumentedConstructor(java.lang.Class resultClass,
                                                                            java.lang.Object[] fieldValues,
                                                                            java.lang.Class[] fieldTypes)

Convenience method to create an instance of the result class with the provided field values, using a constructor taking the arguments. If the returned object is null there is no constructor with the correct signature. Tries to find a constructor taking the required arguments. Uses the fieldTypes first (if specified), then (if not specified) uses the type of the fieldValues, otherwise uses Object as the argument type.

Parameters:

resultClass - The class of results that need creating

fieldValues - The field values

fieldTypes - The field types (optional). If specified needs same number as fieldValues

Returns:

The result class object

createResultObjectUsingDefaultConstructorAndSetters

public static java.lang.Object createResultObjectUsingDefaultConstructorAndSetters(java.lang.Class resultClass,
                                                                                   java.lang.String[] resultFieldNames,
                                                                                   java.util.Map resultClassFieldNames,
                                                                                   java.lang.Object[] fieldValues)

Convenience method to create an instance of the result class with the provided field values, using the default constructor and setting the fields using either public fields, or setters, or a put method. If one of these parts is not found in the result class the returned object is null.

Parameters:

resultClass - Result class that we need to create an object of

resultFieldNames - Names of the fields in the results

resultClassFieldNames - Map of the result class fields, keyed by the field name

fieldValues - The field values

Returns:

The result class object

createResultObjectUsingDefaultConstructorAndSetters

public static java.lang.Object createResultObjectUsingDefaultConstructorAndSetters(java.lang.Class resultClass,
                                                                                   java.lang.String[] resultFieldNames,
                                                                                   java.lang.reflect.Field[] resultFields,
                                                                                   java.lang.Object[] fieldValues)

Convenience method to create an instance of the result class with the provided field values, using the default constructor and setting the fields using either public fields, or setters, or a put method. If one of these parts is not found in the result class the returned object is null.

Parameters:

resultClass - Result class that we need to create an object of

resultFieldNames - Names of the fields in the results

resultFields - (java.lang.reflect.)Field objects for the fields in the results

fieldValues - The field values

Returns:

The result class object

getPublicSetMethodForFieldOfResultClass

public static java.lang.reflect.Method getPublicSetMethodForFieldOfResultClass(java.lang.Class resultClass,
                                                                               java.lang.String fieldName,
                                                                               java.lang.Class fieldType)

Convenience method to return the setXXX method for a field of the result class.

Parameters:

resultClass - The result class

fieldName - Name of the field

fieldType - The type of the field being set

Returns:

The setter method

getPublicPutMethodForResultClass

public static java.lang.reflect.Method getPublicPutMethodForResultClass(java.lang.Class resultClass)

Convenience method to return the put(Object, Object method for the result class.

Parameters:

resultClass - The result class

Returns:

The put(Object, Object) method

getExpressionsFromString

public static java.lang.String[] getExpressionsFromString(java.lang.String str)

Convenience method to split an expression string into its constituent parts where separated by commas. This is used in the case of, for example, a result specification, to get the column definitions.

Parameters:

str - The expression string

Returns:

The expression parts

getValueForParameterExpression

public static java.lang.Object getValueForParameterExpression(java.util.Map parameterValues,
                                                              ParameterExpression paramExpr)

Convenience method to get the value for a ParameterExpression.

Parameters:

parameterValues - Input parameter values keyed by the parameter name/position

paramExpr - Expression

Returns:

The value in the object for this expression

getStringValue

public static java.lang.String getStringValue(java.lang.Object obj)

Convenience method to get the String value for an Object. Currently String, Character and Number are supported.

Parameters:

obj - Object

Returns:

The String value for the Object

getStringValueForExpression

public static java.lang.String getStringValueForExpression(Expression expr,
                                                           java.util.Map parameters)

Convenience method to get the String value for an Expression. Currently only ParameterExpression and Literal are supported.

Parameters:

expr - Expression

parameters - Input parameters

Returns:

The String value in the object for this expression

compareExpressionValues

public static boolean compareExpressionValues(java.lang.Object left,
                                              java.lang.Object right,
                                              Expression.Operator op)

Convenience method to compare two expression values against the specified operator. Returns true if "left {operator} right" is true. The operator can be <, >, <=, <=, ==, !=.

Parameters:

left - Left object

right - Right object

op - Operator

Returns:

Whether the comparison is true

Throws:

NucleusException - if the comparison is impossible

expressionHasOrOperator

public static boolean expressionHasOrOperator(Expression expr)

Convenience method to return if there is an OR operator in the expression. Allows for hierarchical expressions, navigating down through the expression tree.

Parameters:

expr - The expression

Returns:

Whether there is an OR

expressionHasNotOperator

public static boolean expressionHasNotOperator(Expression expr)

Convenience method to return if there is a NOT operator in the expression. Allows for hierarchical expressions, navigating down through the expression tree.

Parameters:

expr - The expression

Returns:

Whether there is a NOT

getParameterExpressionForPosition

public static ParameterExpression getParameterExpressionForPosition(Expression rootExpr,
                                                                    int pos)

Convenience method to return the ParameterExpression for the specified position if found in the expression tree starting at

rootExpr

Parameters:

rootExpr - The expression

pos - The position

Returns:

The ParameterExpression (if found)

queryParameterTypesAreCompatible

public static boolean queryParameterTypesAreCompatible(java.lang.Class cls1,
                                                       java.lang.Class cls2)

getKeyForQueryResultsCache

public static java.lang.String getKeyForQueryResultsCache(Query query,
                                                          java.util.Map params)

Convenience method to generate the "key" for storing the query results of a query with parameters. The key will be of the form

 JDOQL:SELECT FROM myClass WHERE myFilter:123456
 

where "123456" is the hashCode of the parameters for the query

Parameters:

query - The query

params - The params

Returns:

The key