Examples of org.apache.metamodel.DataContext

org.apache.metamodel.DataContext
A DataContext represents the central entry point for interactions with datastores. The DataContext contains of the structure of data (in the form of schemas) and interactions (in the form of queries) with data. @author Kasper Sørensen

    Column fooColumn = source.getColumnByQualifiedLabel("schema.table.foo");
    assertNotNull(fooColumn);


    Map<Column, TypeConverter<?, ?>> converters = new HashMap<Column, TypeConverter<?, ?>>();
    converters.put(fooColumn, new StringToIntegerConverter());
    DataContext converted = Converters.addTypeConverter(source, fooColumn,
        new StringToIntegerConverter());


    // only select "bar" which is not converted
    Table table = converted.getDefaultSchema().getTableByName("table");
    Query query = converted.query().from(table).select("bar").toQuery();
    assertEquals("SELECT table.bar FROM schema.table", query.toSql());


    DataSet ds = converted.executeQuery(query);
    assertEquals(InMemoryDataSet.class, ds.getClass());


  }

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        if (delegate == null) {
            throw new UnsupportedOperationException("Unsupported DataContext type: " + _type);
        }


        final DataContext dataContext = delegate.createDataContext(this);
        if (dataContext == null) {
            throw new IllegalStateException("Factory method failed to produce a non-null DataContext instance");
        }


        return dataContext;

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                .readFileAsString(targetFile).replaceAll("\n", "!LINEBREAK!"));
    }


    public void testHandlingOfEmptyLinesMultipleLinesSupport() throws Exception {
        // test with multiline values
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_with_empty_lines.csv"),
                new CsvConfiguration(1, false, true));
        testHandlingOfEmptyLines(dc);
    }

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        testHandlingOfEmptyLines(dc);
    }


    public void testHandlingOfEmptyLinesSingleLinesSupport() throws Exception {
        // test with only single line values
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_with_empty_lines.csv"),
                new CsvConfiguration(1, false, false));
        testHandlingOfEmptyLines(dc);
    }

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        assertFalse(ds.next());
        ds.close();
    }


    public void testEmptyFileNoHeaderLine() throws Exception {
        DataContext dc = new CsvDataContext(new File("src/test/resources/empty_file.csv"), new CsvConfiguration(
                CsvConfiguration.NO_COLUMN_NAME_LINE));
        assertEquals(1, dc.getDefaultSchema().getTableCount());


        Table table = dc.getDefaultSchema().getTables()[0];
        assertEquals("empty_file.csv", table.getName());
        assertEquals(0, table.getColumnCount());
    }

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        assertEquals("empty_file.csv", table.getName());
        assertEquals(0, table.getColumnCount());
    }


    public void testUnexistingHeaderLine() throws Exception {
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_people.csv"), new CsvConfiguration(20));
        assertEquals(1, dc.getDefaultSchema().getTableCount());


        Table table = dc.getDefaultSchema().getTables()[0];
        assertEquals("csv_people.csv", table.getName());
        assertEquals(0, table.getColumnCount());
    }

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    }


    public void testInconsistentColumns() throws Exception {
        CsvConfiguration conf = new CsvConfiguration(CsvConfiguration.DEFAULT_COLUMN_NAME_LINE, "UTF8", ',', '"', '\\',
                true);
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_inconsistent_columns.csv"), conf);
        DataSet ds = dc.query().from("csv_inconsistent_columns.csv").select("hello").and("world").execute();
        assertTrue(ds.next());
        assertTrue(ds.next());


        try {
            ds.next();

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        assertTrue(ds.next());
        assertFalse(ds.next());
    }


    public void testApproximatedCountSmallFile() throws Exception {
        DataContext dc = new CsvDataContext(new File("src/test/resources/csv_people.csv"));


        Table table = dc.getDefaultSchema().getTables()[0];
        Query q = dc.query().from(table).selectCount().toQuery();
        SelectItem selectItem = q.getSelectClause().getItem(0);
        selectItem.setFunctionApproximationAllowed(true);


        DataSet ds = dc.executeQuery(q);
        assertTrue(ds.next());
        Object[] values = ds.getRow().getValues();
        assertEquals(1, values.length);
        assertEquals(9, ((Long) ds.getRow().getValue(selectItem)).intValue());
        assertEquals(9, ((Long) values[0]).intValue());

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        assertEquals("[michael]", Arrays.toString(result.get(0)));
        assertEquals("[hillary]", Arrays.toString(result.get(1)));
    }


    public void testGetFromInputStream() throws Exception {
        DataContext dc = null;


        // repeat this step a few times to test temp-file creation, see Ticket
        // #437
        for (int i = 0; i < 5; i++) {
            File file = new File("src/test/resources/tickets.csv");
            FileInputStream inputStream = new FileInputStream(file);
            dc = new CsvDataContext(inputStream, new CsvConfiguration());
        }


        Schema schema = dc.getDefaultSchema();
        String name = schema.getTable(0).getName();
        assertTrue(name.startsWith("metamodel"));
        assertTrue(name.endsWith("csv"));


        // Test two seperate reads to ensure that the temp file is working

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        doTicketFileTests(dc);
    }


    public void testMultilineExample() throws Exception {
        File file = new File("src/test/resources/tickets.csv");
        DataContext dc = new CsvDataContext(file);
        Schema schema = dc.getDefaultSchema();
        Table table = schema.getTableByName("tickets.csv");
        Column descColumn = table.getColumnByName("_description");


        assertNotNull(table);
        assertNotNull(descColumn);

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org.apache.metamodel.convert.ConvertedDataSetInterceptorTest

org.apache.metamodel.convert.Converters

org.apache.metamodel.csv.CsvBigFileMemoryTest

org.apache.metamodel.csv.CsvDataContextTest

org.apache.metamodel.excel.ExcelDataContextTest

org.apache.metamodel.fixedwidth.FixedWidthDataContextTest

org.apache.metamodel.intercept.InterceptableDataContextTest

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org.apache.metamodel.jdbc.DerbyTest

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