Add new option for rename response column names

clickhouse-client/src/main/java/com/clickhouse/client/config/ClickHouseClientOption.java

@@ -123,6 +123,11 @@ public enum ClickHouseClientOption implements ClickHouseOption {
      */
     MAX_THREADS_PER_CLIENT("max_threads_per_client", 0,
             "Size of thread pool for each client instance, 0 or negative number means the client will use shared thread pool."),
+    /**
+     * Method to rename response columns.
+     */
+    RENAME_RESPONSE_COLUMN("rename_response_column", ClickHouseRenameMethod.NONE,
+            "Method to rename response columns."),
     /**
      * Whether to enable retry.
      */

clickhouse-client/src/main/java/com/clickhouse/client/config/ClickHouseRenameMethod.java

@@ -0,0 +1,97 @@
+package com.clickhouse.client.config;
+
+import java.util.function.UnaryOperator;
+
+/**
+ * Methods for renaming.
+ */
+public enum ClickHouseRenameMethod {
+    /**
+     * No OP.
+     */
+    NONE(null),
+    /**
+     * Removes prefix including the dot. So "d.t.col1" becomes "col1" and "col2"
+     * remains the same.
+     */
+    REMOVE_PREFIX(s -> {
+        int index = s.lastIndexOf('.');
+        return index >= 0 ? s.substring(index + 1) : s;
+    }),
+
+    /**
+     * Replaces whitespace and underscore to camel case. So "a simple_column"
+     * becomes "aSimpleColumn" and "col_1 2" becomes "col12".
+     */
+    TO_CAMELCASE(s -> {
+        StringBuilder builder = new StringBuilder(s.length());
+        boolean toUpperCase = false;
+        for (char ch : s.toCharArray()) {
+            if (Character.isWhitespace(ch) || ch == '_') {
+                toUpperCase = true;
+            } else if (toUpperCase) {
+                builder.append(Character.toUpperCase(ch));
+                toUpperCase = false;
+            } else {
+                builder.append(ch);
+            }
+        }
+        return builder.toString();
+    }),
+    /**
+     * Removes prefix and replace whitespace and underscore to camel case.
+     */
+    TO_CAMELCASE_WITHOUT_PREFIX(s -> TO_CAMELCASE.rename(REMOVE_PREFIX.rename(s))),
+    /**
+     * Replaces whitespace and camel case to underscore. So "aSimpleColumn" becomes
+     * "a_simple_column" and "col12" becomes "col_12".
+     */
+    TO_UNDERSCORE(s -> {
+        StringBuilder builder = new StringBuilder(s.length() + 5);
+        int prev = -1; // 0 - normal, 1 - whitespace, 2 - upper case
+        for (char ch : s.toCharArray()) {
+            if (Character.isWhitespace(ch)) {
+                if (prev == 0) {
+                    builder.append('_');
+                }
+                prev = 1;
+            } else if (Character.isUpperCase(ch)) {
+                if (prev == 0) {
+                    builder.append('_').append(Character.toLowerCase(ch));
+                } else if (prev == 1) {
+                    builder.append(Character.toLowerCase(ch));
+                } else {
+                    builder.append(ch);
+                }
+                prev = 2;
+            } else {
+                builder.append(ch);
+                prev = 0;
+            }
+        }
+        return builder.toString();
+    }),
+    /**
+     * Removes prefix and replace whitespace and camel case to underscore.
+     */
+    TO_UNDERSCORE_WITHOUT_PREFIX(s -> TO_UNDERSCORE.rename(REMOVE_PREFIX.rename(s)));
+
+    private final UnaryOperator<String> renameFunc;
+
+    ClickHouseRenameMethod(UnaryOperator<String> renameFunc) {
+        this.renameFunc = renameFunc;
+    }
+
+    /**
+     * Rename the given name.
+     *
+     * @param name name to change
+     * @return non-null new name
+     */
+    public String rename(String name) {
+        if (name == null) {
+            name = "";
+        }
+        return renameFunc != null ? renameFunc.apply(name) : name;
+    }
+}

clickhouse-client/src/main/java/com/clickhouse/client/data/ClickHouseRowBinaryProcessor.java

@@ -25,6 +25,8 @@
 import com.clickhouse.client.ClickHouseSerializer;
 import com.clickhouse.client.ClickHouseValue;
 import com.clickhouse.client.ClickHouseValues;
+import com.clickhouse.client.config.ClickHouseClientOption;
+import com.clickhouse.client.config.ClickHouseRenameMethod;
 
 /**
  * Data processor for handling {@link ClickHouseFormat#RowBinary} and
@@ -521,10 +523,12 @@ protected List<ClickHouseColumn> readColumns() throws IOException {
             names[i] = input.readUnicodeString();
         }
 
+        ClickHouseRenameMethod m = (ClickHouseRenameMethod) config
+                .getOption(ClickHouseClientOption.RENAME_RESPONSE_COLUMN);
         List<ClickHouseColumn> columns = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
             // a bit risky here - what if ClickHouse support user type?
-            columns.add(ClickHouseColumn.of(names[i], input.readAsciiString()));
+            columns.add(ClickHouseColumn.of(m.rename(names[i]), input.readAsciiString()));
         }
 
         return columns;

clickhouse-client/src/main/java/com/clickhouse/client/data/ClickHouseTabSeparatedProcessor.java

@@ -20,6 +20,8 @@
 import com.clickhouse.client.ClickHouseRecord;
 import com.clickhouse.client.ClickHouseSerializer;
 import com.clickhouse.client.ClickHouseValue;
+import com.clickhouse.client.config.ClickHouseClientOption;
+import com.clickhouse.client.config.ClickHouseRenameMethod;
 import com.clickhouse.client.data.tsv.ByteFragment;
 
 public class ClickHouseTabSeparatedProcessor extends ClickHouseDataProcessor {
@@ -288,10 +290,12 @@ protected List<ClickHouseColumn> readColumns() throws IOException {
                     buf.lastByte() == getTextHandler().rowDelimiter ? buf.length() - 1 : buf.length());
             types = toStringArray(typesFragment, getTextHandler().colDelimiter);
         }
-        List<ClickHouseColumn> list = new ArrayList<>(cols.length);
 
+        ClickHouseRenameMethod m = (ClickHouseRenameMethod) config
+                .getOption(ClickHouseClientOption.RENAME_RESPONSE_COLUMN);
+        List<ClickHouseColumn> list = new ArrayList<>(cols.length);
         for (int i = 0; i < cols.length; i++) {
-            list.add(ClickHouseColumn.of(cols[i], types == null ? "Nullable(String)" : types[i]));
+            list.add(ClickHouseColumn.of(m.rename(cols[i]), types == null ? "Nullable(String)" : types[i]));
         }
 
         return list;

clickhouse-client/src/test/java/com/clickhouse/client/ClientIntegrationTest.java

@@ -23,6 +23,7 @@
 import java.util.stream.Collectors;
 
 import com.clickhouse.client.config.ClickHouseClientOption;
+import com.clickhouse.client.config.ClickHouseRenameMethod;
 import com.clickhouse.client.config.ClickHouseSslMode;
 import com.clickhouse.client.data.BinaryStreamUtils;
 import com.clickhouse.client.data.ClickHouseBigDecimalValue;
@@ -93,6 +94,18 @@ protected Object[][] getCompressionMatrix() {
                 new Object[] { false, true } };
     }
 
+    @DataProvider(name = "renameMethods")
+    protected Object[][] getRenameMethods() {
+        return new Object[][] {
+                new Object[] { null, "a b c", " ", "d.E_f" },
+                new Object[] { ClickHouseRenameMethod.NONE, "a b c", " ", "d.E_f" },
+                new Object[] { ClickHouseRenameMethod.REMOVE_PREFIX, "a b c", " ", "E_f" },
+                new Object[] { ClickHouseRenameMethod.TO_CAMELCASE, "aBC", "", "d.EF" },
+                new Object[] { ClickHouseRenameMethod.TO_CAMELCASE_WITHOUT_PREFIX, "aBC", "", "EF" },
+                new Object[] { ClickHouseRenameMethod.TO_UNDERSCORE, "a_b_c", "", "d._e_f" },
+                new Object[] { ClickHouseRenameMethod.TO_UNDERSCORE_WITHOUT_PREFIX, "a_b_c", "", "E_f" }, };
+    }
+
     @DataProvider(name = "simpleTypeProvider")
     protected Object[][] getSimpleTypes() {
         return new Object[][] {
@@ -1073,6 +1086,21 @@ public void testInsertWithInputFunction() throws Exception {
         }
     }
 
+    @Test(dataProvider = "renameMethods", groups = "integration")
+    public void testRenameResponseColumns(ClickHouseRenameMethod m, String col1, String col2, String col3)
+            throws Exception {
+        ClickHouseNode server = getServer();
+        try (ClickHouseClient client = getClient();
+                ClickHouseResponse resp = client.connect(server)
+                        .format(ClickHouseFormat.RowBinaryWithNamesAndTypes)
+                        .option(ClickHouseClientOption.RENAME_RESPONSE_COLUMN, m)
+                        .query("select 1 `a b c`, 2 ` `, 3 `d.E_f`").execute().get()) {
+            Assert.assertEquals(resp.getColumns().get(0).getColumnName(), col1);
+            Assert.assertEquals(resp.getColumns().get(1).getColumnName(), col2);
+            Assert.assertEquals(resp.getColumns().get(2).getColumnName(), col3);
+        }
+    }
+
     @Test(groups = "integration")
     public void testTempTable() throws Exception {
         ClickHouseNode server = getServer();

clickhouse-client/src/test/java/com/clickhouse/client/config/ClickHouseRenameMethodTest.java

@@ -0,0 +1,58 @@
+package com.clickhouse.client.config;
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class ClickHouseRenameMethodTest {
+    @Test(groups = { "unit" })
+    public void testRenameNullOrEmptyString() {
+        for (ClickHouseRenameMethod m : ClickHouseRenameMethod.values()) {
+            Assert.assertEquals(m.rename(null), "");
+            Assert.assertEquals(m.rename(""), "");
+        }
+    }
+
+    @Test(groups = { "unit" })
+    public void testNone() {
+        Assert.assertEquals(ClickHouseRenameMethod.NONE.rename("\t \n \r"), "\t \n \r");
+        Assert.assertEquals(ClickHouseRenameMethod.NONE.rename("test 1 2 3"), "test 1 2 3");
+    }
+
+    @Test(groups = { "unit" })
+    public void testRemovePrefix() {
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("\t \n \r"), "\t \n \r");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("test 1 2 3"), "test 1 2 3");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("test.1 2 3"), "1 2 3");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("test.1.2.3"), "3");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename(".test"), "test");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("test."), "");
+        Assert.assertEquals(ClickHouseRenameMethod.REMOVE_PREFIX.rename("."), "");
+    }
+
+    @Test(groups = { "unit" })
+    public void testCamelCase() {
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename("\t \n \r"), "");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename("test 1 2 3"), "test123");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename("test oNE Two_three"), "testONETwoThree");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename("test"), "test");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename(" test"), "Test");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE.rename("test "), "test");
+
+        Assert.assertEquals(ClickHouseRenameMethod.TO_CAMELCASE_WITHOUT_PREFIX.rename("a.test_col"), "testCol");
+    }
+
+    @Test(groups = { "unit" })
+    public void testUnderscore() {
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("\t \n \r"), "");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("TEST"), "TEST");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("Test"), "Test");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("TestONE"), "Test_oNE");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("Test ONE"), "Test_oNE");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("Test  oneTwo"), "Test_one_two");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("testOnetWo"), "test_onet_wo");
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE.rename("test12Three"), "test12_three");
+
+        Assert.assertEquals(ClickHouseRenameMethod.TO_UNDERSCORE_WITHOUT_PREFIX.rename("a.t.est1\t 2Three"),
+                "est1_2_three");
+    }
+}