public class QueryHelper extends Object
QueryHelper is a utility class that provides a set of factory methods used for building instances of Filter
or ValueExtractor
.
The QueryHelper API accepts a String that specifies the creation of rich Filters in a format similar to SQL WHERE
clauses. For example, the String "street = 'Main' and state = 'TX'"
will create a tree of Filters similar to the following Java code:
new AndFilter(
new EqualsFilter("getStreet","Main"),
new EqualsFilter("getState","TX"));
The following keywords are currently supported (words between brackets are optional):
=, >, >=, <, <=, <>, [ NOT ] BETWEEN, [ NOT ] LIKE, [ NOT ] IN, IS [ NOT ] NULL , CONTAINS [ ALL | ANY ]
(AND, OR, NOT)
true, false
, and null
ReflectionExtractor
. Additionally, the "."
operator will use ChainedExtractor
. Pseudo functions key()
and value()
may be used to specify the use of a key as in "key() between 10 and 50"
. The value()
pseudo function is a shorthand for IdentityExtractor
.
Query bind variables are supported in two forms. One form is a "?"
followed by a position number; for example: "dept = ?1 and serviceCode in [10,20,30]"
. For this usage, supply an Object array of parameters to createFilter(String, Object[])
. Note: this scheme treats 1 as the starting index into the array.
Additionally, named bind parameters are supported. The above example could be: "dept = :deptNum and serviceCode in :myList"
. This style requires the use of a Map with createFilter(String, Map)
. Both forms can be used in the same specification.
The factory methods catch a number of Exceptions from the implementation stages and subsequently may throw an unchecked FilterBuildingException
.
Modifier and Type | Field and Description |
---|---|
protected static CoherenceQueryLanguage |
f_language
The default
CoherenceQueryLanguage used by this QueryHelper when no language is provided to methods. |
Constructor and Description |
---|
QueryHelper() |
Modifier and Type | Method and Description |
---|---|
static ValueExtractor |
createExtractor(String s)
Make a new ValueExtractor from the given String.
|
static ValueExtractor |
createExtractor(String sQuery, CoherenceQueryLanguage language)
Make a new ValueExtractor from the given String.
|
static Filter |
createFilter(String sWhereClause)
Make a new Filter from the given String.
|
static Filter |
createFilter(String sWhereClause, Map mapBindings)
Make a new Filter from the given String.
|
static Filter |
createFilter(String sWhereClause, Object[] aBindings)
Make a new Filter from the given String.
|
static Filter |
createFilter(String sWhereClause, Object[] aBindings, Map mapBindings)
Make a new Filter from the given String.
|
static Filter |
createFilter(String sWhereClause, Object[] aBindings, Map mapBindings, CoherenceQueryLanguage language)
Make a new Filter from the given String.
|
static Object |
executeStatement(String sStatement)
Execute a CohQL statement.
|
static Object |
executeStatement(String sStatement, ExecutionContext context)
Execute a CohQL statement.
|
protected static Term |
parse(String sQuery)
Return the
Term representing the AST produced by parsing the specified CohQL query String. |
protected static Term |
parse(String sQuery, CoherenceQueryLanguage language)
Return the
Term representing the AST produced by parsing the specified CohQL query String. |
protected static final CoherenceQueryLanguage f_language
CoherenceQueryLanguage
used by this QueryHelper when no language is provided to methods.public static Filter createFilter(String sWhereClause)
sWhereClause
- a String in the Coherence Query Language representing a FilterFilterBuildingException
- may be thrownpublic static Filter createFilter(String sWhereClause, Object[] aBindings)
sWhereClause
- a String in the Coherence Query Language representing a FilteraBindings
- the array of Objects to use for Bind variablesFilterBuildingException
- may be thrownpublic static Filter createFilter(String sWhereClause, Map mapBindings)
sWhereClause
- a String in the Coherence Query Language representing a FiltermapBindings
- the Map of Objects to use for Bind variablesFilterBuildingException
- may be thrownpublic static Filter createFilter(String sWhereClause, Object[] aBindings, Map mapBindings)
sWhereClause
- a String in the Coherence Query Language representing a FilteraBindings
- the array of Objects to use for Bind variablesmapBindings
- the Map of Objects to use for Bind variablesFilterBuildingException
- may be thrownpublic static Filter createFilter(String sWhereClause, Object[] aBindings, Map mapBindings, CoherenceQueryLanguage language)
sWhereClause
- a String in the Coherence Query Language representing a FilteraBindings
- the array of Objects to use for indexed Bind variablesmapBindings
- the Map of Objects to use for named Bind variableslanguage
- the CoherenceQueryLanguage instance to useFilterBuildingException
- may be thrownpublic static ValueExtractor createExtractor(String s)
s
- a String in the Coherence Query Language representing a ValueExtractorFilterBuildingException
- may be thrownpublic static ValueExtractor createExtractor(String sQuery, CoherenceQueryLanguage language)
sQuery
- a String in the Coherence Query Language representing a ValueExtractorlanguage
- the CoherenceQueryLanguage instance to useFilterBuildingException
- may be thrownprotected static Term parse(String sQuery)
Term
representing the AST produced by parsing the specified CohQL query String.sQuery
- the CohQL query to be parsedprotected static Term parse(String sQuery, CoherenceQueryLanguage language)
Term
representing the AST produced by parsing the specified CohQL query String. This method takes a CoherenceQueryLanguage parameter which allows CohQL customisations to be applied to the CohQL syntax.sQuery
- the CohQL query to be parsedlanguage
- the CoherenceQueryLanguage instance to usepublic static Object executeStatement(String sStatement)
Return Type | Query Description |
---|---|
Cache entry value | If the statement is an INSERT operation the previous entry for the given key will be returned; otherwise null |
Number |
If the query is an aggregation that returns a single numerical value; for example: count() , avg() , max() , min() |
Map |
If query has a grouping |
Collection |
For all other SELECT , DELETE , UPDATE statements |
null |
If the query returns no results or for create/delete index or drop/create cache, or backup/restore |
sStatement
- a Coherence Query Language statementRuntimeException
- if an invalid query is providedpublic static Object executeStatement(String sStatement, ExecutionContext context)
Return Type | Query Description |
---|---|
Cache entry value | If the statement is an INSERT operation the previous entry for the given key will be returned; otherwise null |
Number |
If the query is an aggregation that returns a single numerical value; for example: count() , avg() , max() , min() |
Map |
If query has a grouping |
Collection |
For all other SELECT , DELETE , UPDATE statements |
null |
If the query returns no results or for create/delete index or drop/create cache, or backup/restore |
sStatement
- a Coherence Query Language statementcontext
- the ExecutionContext
to useRuntimeException
- if an invalid query is provided