com.mongodb.jdbc.MongoSQLResultSetMetaData Maven / Gradle / Ivy

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JDBC Driver for MongoDB Atlas SQL interface
There is a newer version: 2.2.0
package com.mongodb.jdbc;

import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MongoSQLResultSetMetaData extends MongoResultSetMetaData implements ResultSetMetaData {
    private static class NameSpace {
        String datasource;
        String columnLabel;

        NameSpace(String datasource, String columnLabel) {
            this.datasource = datasource;
            this.columnLabel = columnLabel;
        }
    }

    private static class DatasourceAndIndex {
        String datasource;
        int index;

        DatasourceAndIndex(String datasource, int index) {
            this.datasource = datasource;
            this.index = index;
        }
    }

    // A mapping from columnLabel name to datasource name and index.
    private Map columnLabels;
    // A mapping from index position to NameSpace (datasource, columnLabel).
    private List columnIndices;
    // A mapping from index position to ColumnTypeInfo.
    private List columnInfo;

    // This gets the datasource for a given columnLabel, and is used
    // in MongoSQLResultSet to retrieve data by label.
    String getDatasource(String columnLabel) {
        return columnLabels.get(columnLabel).datasource;
    }

    private void assertDatasourceSchema(MongoJsonSchema schema) throws SQLException {
        // A Datasource Schema must be an Object Schema, and unlike Object Schemata in general,
        // the properties field cannot be null.
        if (!schema.isObject() || schema.properties == null) {
            throw new SQLException("ResultSetMetaData json schema must be object with properties");
        }
    }

    private void processDataSource(
            MongoJsonSchema schema, String datasource, boolean sortFieldsAlphabetically)
            throws SQLException {
        MongoJsonSchema datasourceSchema = schema.properties.get(datasource);
        assertDatasourceSchema(datasourceSchema);

        String[] fields = datasourceSchema.properties.keySet().toArray(new String[0]);
        if (sortFieldsAlphabetically) {
            Arrays.sort(fields);
        }

        for (String field : fields) {
            MongoJsonSchema columnSchema = datasourceSchema.properties.get(field);
            BsonTypeInfo columnBsonTypeInfo = columnSchema.getBsonTypeInfo();
            int nullability = datasourceSchema.getColumnNullability(field);
            columnIndices.add(new NameSpace(datasource, field));
            columnInfo.add(
                    new MongoSQLColumnInfo(datasource, field, columnBsonTypeInfo, nullability));
            if (!columnLabels.containsKey(field)) {
                columnLabels.put(
                        field, new DatasourceAndIndex(datasource, columnIndices.size() - 1));
            }
        }
    };

    public MongoSQLResultSetMetaData(MongoJsonSchema schema, boolean sortFieldsAlphabetically)
            throws SQLException {
        assertDatasourceSchema(schema);

        columnLabels = new HashMap();
        columnIndices = new ArrayList();
        columnInfo = new ArrayList();

        String[] datasources = schema.properties.keySet().toArray(new String[0]);
        Arrays.sort(datasources);

        for (String datasource : datasources) {
            processDataSource(schema, datasource, sortFieldsAlphabetically);
        }
    }

    public int getColumnPositionFromLabel(String label) {
        return columnLabels.get(label).index;
    }

    public boolean hasColumnWithLabel(String label) {
        return columnLabels.containsKey(label);
    }

    @Override
    public MongoColumnInfo getColumnInfo(int column) throws SQLException {
        checkBounds(column);
        return columnInfo.get(column - 1);
    }

    @Override
    public int getColumnCount() throws SQLException {
        return columnIndices.size();
    }
}