AbstractDataContext (MetaModel 5.3.1 API)

java.lang.Object
- org.apache.metamodel.AbstractDataContext

All Implemented Interfaces:

DataContext

Direct Known Subclasses:

CompositeDataContext, JdbcDataContext, OpenOfficeDataContext, QueryPostprocessDataContext
```
@InterfaceStability.Evolving
public abstract class AbstractDataContext
extends Object
implements DataContext
```
Abstract implementation of the DataContext interface. Provides convenient implementations of all trivial and datastore-independent methods.

Constructor Summary

Constructors
Constructor and Description

AbstractDataContext()

Constructors
Constructor and Description
`AbstractDataContext()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`CompiledQuery`	`compileQuery(Query query)` Compiles a query, preparing it for reuse.
`DataSet`	`executeQuery(CompiledQuery compiledQuery, Object... values)` Executes a compiled query with given values as parameters.
`DataSet`	`executeQuery(String queryString)` Parses and executes a string-based SQL query.
`Column`	`getColumnByQualifiedLabel(String columnName)` Finds a column in the DataContext based on a fully qualified column label.
`Schema`	`getDefaultSchema()` Gets the default schema of this DataContext.
`protected abstract String`	`getDefaultSchemaName()` Gets the name of the default schema.
`Schema`	`getSchemaByName(String name)` Gets a schema by a specified name.
`protected abstract Schema`	`getSchemaByNameInternal(String name)` Gets a specific schema from the non-abstract implementation.
`List<String>`	`getSchemaNames()` m Gets the names of all schemas within this DataContext.
`protected abstract List<String>`	`getSchemaNamesInternal()` Gets schema names from the non-abstract implementation.
`List<Schema>`	`getSchemas()` Gets all schemas within this DataContext.
`Table`	`getTableByQualifiedLabel(String tableName)` Finds a table in the DataContext based on a fully qualified table label.
`protected boolean`	`isQualifiedPathDelim(char c)`
`protected void`	`onSchemaCacheRefreshed()` Method invoked when schemas have been refreshed using `refreshSchemas()`.
`Query`	`parseQuery(String queryString)` Parses a string-based SQL query and produces a corresponding `Query` object.
`InitFromBuilder`	`query()` Starts building a query using the query builder API.
`DataContext`	`refreshSchemas()` Enforces a refresh of the schemas.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.metamodel.DataContext
executeQuery

- Constructor Detail
  - AbstractDataContext
```
public AbstractDataContext()
```
- Method Detail
  - refreshSchemas
```
public final DataContext refreshSchemas()
```
    Enforces a refresh of the schemas. If not refreshed, cached schema objects may be used.
    
    Specified by:
    
    refreshSchemas in interface DataContext
    
    Returns:
    
    this DataContext
  - onSchemaCacheRefreshed
```
protected void onSchemaCacheRefreshed()
```
    Method invoked when schemas have been refreshed using refreshSchemas(). Can be overridden to add callback functionality in subclasses.
  - getSchemas
```
public final List<Schema> getSchemas()
                              throws MetaModelException
```
    Gets all schemas within this DataContext.
    
    Specified by:
    
    getSchemas in interface DataContext
    
    Returns:
    
    the schemas in this data context. Schemas are cached for reuse in many situations so if you want to update the schemas, use the refreshSchemas() method.
    
    Throws:
    
    MetaModelException - if an error occurs retrieving the schema model
  - getSchemaNames
```
public final List<String> getSchemaNames()
                                  throws MetaModelException
```
    m Gets the names of all schemas within this DataContext.
    
    Specified by:
    
    getSchemaNames in interface DataContext
    
    Returns:
    
    an array of valid schema names
    
    Throws:
    
    MetaModelException - if an error occurs retrieving the schema model
  - getDefaultSchema
```
public final Schema getDefaultSchema()
                              throws MetaModelException
```
    Gets the default schema of this DataContext.
    
    Specified by:
    
    getDefaultSchema in interface DataContext
    
    Returns:
    
    the schema that you are most probable to be interested in. The default schema is determined by finding the schema with most available of tables. In a lot of situations there will only be a single available schema and in that case this will of course be the schema returned.
    
    Throws:
    
    MetaModelException - if an error occurs retrieving the schema model
  - query
```
public final InitFromBuilder query()
```
    Starts building a query using the query builder API. This way of building queries is the preferred approach since it provides a more type-safe approach to building API's as well as allows the DataContext implementation to be aware of the query building process.
    
    Specified by:
    
    query in interface DataContext
    
    Returns:
    
    a query builder component at the initial position in building a query.
  - parseQuery
```
public Query parseQuery(String queryString)
                 throws MetaModelException
```
    Parses a string-based SQL query and produces a corresponding Query object.
    
    Specified by:
    
    parseQuery in interface DataContext
    
    Parameters:
    
    queryString - the SQL query to parse
    
    Returns:
    
    a Query object corresponding to the SQL query.
    
    Throws:
    
    MetaModelException - in case the parsing was unsuccesful.
  - compileQuery
```
public CompiledQuery compileQuery(Query query)
                           throws MetaModelException
```
    Description copied from interface: DataContext
    
    Compiles a query, preparing it for reuse. Often times compiled queries have a performance improvement when executed, but at the cost of a preparation time penalty. Therefore it is adviced to use compiled queries when the same query is to be fired multiple times. Compiled queries can contain QueryParameters as operands in the WHERE clause, making it possible to reuse the same query with different parameter values.
    
    Specified by:
    
    compileQuery in interface DataContext
    
    Parameters:
    
    query - the query object to execute, possibly holding one or more QueryParameters.
    
    Returns:
    
    the CompiledQuery after preparing the query
    
    Throws:
    
    MetaModelException - if preparing the query is unsuccesful
    
    See Also:
    
    CompiledQuery, QueryParameter
  - executeQuery
```
public DataSet executeQuery(CompiledQuery compiledQuery,
                            Object... values)
```
    Description copied from interface: DataContext
    
    Executes a compiled query with given values as parameters.
    
    Specified by:
    
    executeQuery in interface DataContext
    
    Parameters:
    
    compiledQuery - the compiledQuery object to execute
    
    values - the values for parameters in the CompiledQuery.
    
    Returns:
    
    the DataSet produced from executing the query.
  - executeQuery
```
public final DataSet executeQuery(String queryString)
                           throws MetaModelException
```
    Parses and executes a string-based SQL query. This method is essentially equivalent to calling first DataContext.parseQuery(String) and then DataContext.executeQuery(Query) with the parsed query.
    
    Specified by:
    
    executeQuery in interface DataContext
    
    Parameters:
    
    queryString - the SQL query to parse
    
    Returns:
    
    the DataSet produced from executing the query
    
    Throws:
    
    MetaModelException - if either parsing or executing the query produces an exception
  - getSchemaByName
```
public final Schema getSchemaByName(String name)
                             throws MetaModelException
```
    Gets a schema by a specified name.
    
    Specified by:
    
    getSchemaByName in interface DataContext
    
    Parameters:
    
    name - the name of the desired schema
    
    Returns:
    
    the Schema with the specified name or null if no such schema exists
    
    Throws:
    
    MetaModelException - if an error occurs retrieving the schema model
  - getColumnByQualifiedLabel
```
public final Column getColumnByQualifiedLabel(String columnName)
```
    Finds a column in the DataContext based on a fully qualified column label. The qualified label consists of the the schema, table and column name, delimited by a dot (.).
    
    Specified by:
    
    getColumnByQualifiedLabel in interface DataContext
    
    Returns:
    
    a column that matches the qualified label, or null if no such column exists
  - getTableByQualifiedLabel
```
public final Table getTableByQualifiedLabel(String tableName)
```
    Finds a table in the DataContext based on a fully qualified table label. The qualified label consists of the the schema and table name, delimited by a dot (.).
    
    Specified by:
    
    getTableByQualifiedLabel in interface DataContext
    
    Returns:
    
    a table that matches the qualified label, or null if no such table exists
  - isQualifiedPathDelim
```
protected boolean isQualifiedPathDelim(char c)
```
  - getSchemaNamesInternal
```
protected abstract List<String> getSchemaNamesInternal()
```
    Gets schema names from the non-abstract implementation. These schema names will be cached except if the refreshSchemas() method is called.
    
    Returns:
    
    an array of schema names.
  - getDefaultSchemaName
```
protected abstract String getDefaultSchemaName()
```
    Gets the name of the default schema.
    
    Returns:
    
    the default schema name.
  - getSchemaByNameInternal
```
protected abstract Schema getSchemaByNameInternal(String name)
```
    Gets a specific schema from the non-abstract implementation. This schema object will be cached except if the refreshSchemas() method is called.
    
    Parameters:
    
    name - the name of the schema to get
    
    Returns:
    
    a schema object representing the named schema, or null if no such schema exists.

Class AbstractDataContext

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.metamodel.DataContext

Constructor Detail

AbstractDataContext

Method Detail

refreshSchemas

onSchemaCacheRefreshed

getSchemas

getSchemaNames

getDefaultSchema

query

parseQuery

compileQuery

executeQuery

executeQuery

getSchemaByName

getColumnByQualifiedLabel

getTableByQualifiedLabel

isQualifiedPathDelim

getSchemaNamesInternal

getDefaultSchemaName

getSchemaByNameInternal