Examples with SparqlColumnInfo org.apache.jena.jdbc.results.metadata.columns.SparqlColumnInfo used on opensource projects

Example 1 with SparqlColumnInfo

use of org.apache.jena.jdbc.results.metadata.columns.SparqlColumnInfo in project jena by apache.

the class SelectResultsMetadata method makeColumns.

/**
     * Makes column information for SELECT results
     * 
     * @param results
     *            Result Set
     * @param rset
     *            Underlying SPARQL results
     * @return Column information
     * @throws SQLException
     *             Thrown if the column information cannot be created
     */
private static ColumnInfo[] makeColumns(JenaResultSet results, ResultSetPeekable rset) throws SQLException {
    List<String> vars = rset.getResultVars();
    ColumnInfo[] columns = new ColumnInfo[vars.size()];
    int level = JdbcCompatibility.normalizeLevel(results.getJdbcCompatibilityLevel());
    boolean columnsAsStrings = JdbcCompatibility.shouldTypeColumnsAsString(level);
    boolean columnsDetected = JdbcCompatibility.shouldDetectColumnTypes(level);
    Binding b = null;
    if (columnsDetected) {
        if (rset.hasNext()) {
            b = rset.peekBinding();
        } else {
            // If we were supposed to detect columns but there is no data
            // available then we will just fallback to typing everything as
            // strings
            columnsAsStrings = true;
            columnsDetected = false;
        }
    }
    for (int i = 0; i < columns.length; i++) {
        if (!columnsAsStrings && !columnsDetected) {
            // Low compatibility, report columns as being typed as
            // JAVA_OBJECT with ARQ Node as the column class
            columns[i] = new SparqlColumnInfo(vars.get(i), Types.JAVA_OBJECT, columnNullable);
            LOGGER.info("Low JDBC compatibility, column " + vars.get(i) + " is being typed as Node");
        } else if (columnsAsStrings) {
            // Medium compatibility, report columns as being typed as
            // NVARCHAR with String as the column class
            columns[i] = new StringColumn(vars.get(i), columnNullable);
            LOGGER.info("Medium JDBC compatibility, column " + vars.get(i) + " is being typed as String");
        } else if (columnsDetected) {
            // High compatibility, detect columns types based on first row
            // of results
            columns[i] = JdbcCompatibility.detectColumnType(vars.get(i), b.get(Var.alloc(vars.get(i))), true);
            LOGGER.info("High compatibility, column " + vars.get(i) + " was detected as being of type " + columns[i].getClassName());
        } else {
            throw new SQLFeatureNotSupportedException("Unknown JDBC compatibility level was set");
        }
    }
    return columns;
}

Example 2 with SparqlColumnInfo

use of org.apache.jena.jdbc.results.metadata.columns.SparqlColumnInfo in project jena by apache.

the class TripleResultsMetadata method makeColumns.

/**
     * Gets the columns for CONSTRUCT/DESCRIBE results
     * 
     * @param results
     *            Results
     * @param ts
     *            Underlying triples
     * @param subjLabel
     *            Label for subject column, use {@code null} to omit the subject
     *            column
     * @param predLabel
     *            Label for predicate column, use {@code null} to omit the
     *            predicate column
     * @param objLabel
     *            Label for object column, use {@code null} to omit the object
     *            column
     * 
     * @return Column Information
     * @throws SQLException
     */
private static ColumnInfo[] makeColumns(JenaResultSet results, PeekIterator<Triple> ts, String subjLabel, String predLabel, String objLabel) throws SQLException {
    int numColumns = 0;
    if (subjLabel != null)
        numColumns++;
    if (predLabel != null)
        numColumns++;
    if (objLabel != null)
        numColumns++;
    ColumnInfo[] columns = new ColumnInfo[numColumns];
    // Figure out column names
    String[] names = new String[numColumns];
    names[0] = subjLabel != null ? subjLabel : (predLabel != null ? predLabel : objLabel);
    if (numColumns > 1) {
        names[1] = subjLabel != null && predLabel != null ? predLabel : objLabel;
    }
    if (numColumns == 3) {
        names[2] = objLabel;
    }
    int level = JdbcCompatibility.normalizeLevel(results.getJdbcCompatibilityLevel());
    boolean columnsAsStrings = JdbcCompatibility.shouldTypeColumnsAsString(level);
    boolean columnsDetected = JdbcCompatibility.shouldDetectColumnTypes(level);
    Triple t = null;
    Node[] values = new Node[numColumns];
    if (columnsDetected) {
        if (ts.hasNext()) {
            // Need to peek the first Triple and grab appropriate nodes
            t = ts.peek();
            if (numColumns == NUM_COLUMNS) {
                values[0] = t.getSubject();
                values[1] = t.getPredicate();
                values[2] = t.getObject();
            } else {
                values[0] = subjLabel != null ? t.getSubject() : (predLabel != null ? t.getPredicate() : t.getObject());
                if (numColumns > 1) {
                    values[1] = subjLabel != null && predLabel != null ? t.getPredicate() : t.getObject();
                }
            }
        } else {
            // If we were supposed to detect columns but there is no data
            // available then we will just fallback to typing everything as
            // strings
            columnsAsStrings = true;
            columnsDetected = false;
        }
    }
    for (int i = 0; i < columns.length; i++) {
        if (!columnsAsStrings && !columnsDetected) {
            // Low compatibility, report columns as being typed as
            // JAVA_OBJECT with ARQ Node as the column class
            columns[i] = new SparqlColumnInfo(names[i], Types.JAVA_OBJECT, columnNoNulls);
            LOGGER.info("Low JDBC compatibility, column " + names[i] + " is being typed as Node");
        } else if (columnsAsStrings) {
            // Medium compatibility, report columns as being typed as
            // NVARChar with String as the column class
            columns[i] = new StringColumn(names[i], columnNoNulls);
            LOGGER.info("Medium JDBC compatibility, column " + names[i] + " is being typed as String");
        } else if (columnsDetected) {
            // High compatibility, detect columns types based on first row
            // of results
            columns[i] = JdbcCompatibility.detectColumnType(names[i], values[i], false);
            LOGGER.info("High compatibility, column " + names[i] + " was detected as being of type " + columns[i].getClassName());
        } else {
            throw new SQLFeatureNotSupportedException("Unknown JDBC compatibility level was set");
        }
    }
    return columns;
}