How to validate an expression in Apache Calcite - apache-calcite

Question

I want to know how to validate a expression in Calcite. I create a schema and add my table into it, then I want to use Validator to validate a SqlNode which is from an expression. Here is the code.
public class DummyTable extends AbstractTable {
private final String tableName;
public DummyTable(String tableName) {
this.tableName = tableName;
}
#Override
public RelDataType getRowType(RelDataTypeFactory typeFactory) {
RelDataTypeFactory.Builder builder = typeFactory.builder();
builder.add("a", SqlTypeName.BIGINT);
builder.add("b", SqlTypeName.BIGINT);
return builder.build();
}
public String getTableName() {
return tableName;
}
}
public class ConditionValidator {
private final String sql;
private final SchemaPlus rootSchema;
private final FrameworkConfig frameworkConfig;
private final RelDataTypeFactory relDataTypeFactory;
private final CalciteCatalogReader catalogReader;
private final SqlOperatorTable sqlOperatorTable;
private final SqlValidator validator;
public ConditionValidator(String sql) {
this.sql = sql;
SchemaPlus rootSchema = Frameworks.createRootSchema(true);
DummyTable testTable = new DummyTable("test_table");
rootSchema.add(testTable.getTableName(), testTable);
this.rootSchema = rootSchema;
this.frameworkConfig = Frameworks.newConfigBuilder()
.parserConfig(SqlParser.config()
.withLex(Lex.MYSQL)
.withConformance(SqlConformanceEnum.DEFAULT))
.defaultSchema(rootSchema)
.operatorTable(SqlStdOperatorTable.instance())
.build();
this.relDataTypeFactory = new SqlTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
Properties properties = new Properties();
properties.setProperty(CalciteConnectionProperty.CASE_SENSITIVE.camelName(), "true");
this.catalogReader = new CalciteCatalogReader(
CalciteSchema.from(rootSchema),
CalciteSchema.from(rootSchema).path(rootSchema.getName()),
relDataTypeFactory,
new CalciteConnectionConfigImpl(properties));
this.sqlOperatorTable = SqlOperatorTables.chain(frameworkConfig.getOperatorTable(), catalogReader);
this.validator = SqlValidatorUtil.newValidator(sqlOperatorTable, catalogReader, relDataTypeFactory, frameworkConfig.getSqlValidatorConfig());
}
public SqlNode validate() {
SqlParser sqlParser = SqlParser.create(sql, frameworkConfig.getParserConfig());
SqlNode sqlNode;
try {
sqlNode = sqlParser.parseExpression();
} catch (Exception e) {
throw new RuntimeException(e);
}
SqlNode validate = validator.validate(sqlNode);
return validate;
}
}
And now I can validate a SqlNode from a SQL query, for example, when input sql is "select a, b from test_table where a > 1 and b = 1", validation is ok (if validating a query, you should use the way below to parse the sql:
sqlNode = sqlParser.parseQuery(); // not 'sqlParser.parseExpression();
).
However, when I validate an expression like "a > 1 and b = 1", such an exception occurs: "Column 'a' not found in any table". I assume there maybe something wrong with validate scope, but I can't find the solution. Can someone help me? Thanks a lot!