[UC CLI] Make table read honor --output json/jsonPretty

examples/cli/src/main/java/io/unitycatalog/cli/TableCli.java

@@ -57,7 +57,7 @@ public static void handle(CommandLine cmd, ApiClient apiClient, String authToken
         output = getTable(tablesApi, json);
         break;
       case CliUtils.READ:
-        output = readTable(temporaryCredentialsApi, tablesApi, json);
+        output = readTable(temporaryCredentialsApi, tablesApi, json, cmd);
         break;
       case CliUtils.WRITE:
         output = writeTable(temporaryCredentialsApi, tablesApi, json);
@@ -220,8 +220,11 @@ private static String getTable(TablesApi tablesApi, JSONObject json)
   }
 
   private static String readTable(
-      TemporaryCredentialsApi temporaryCredentialsApi, TablesApi tablesApi, JSONObject json)
-      throws ApiException {
+      TemporaryCredentialsApi temporaryCredentialsApi,
+      TablesApi tablesApi,
+      JSONObject json,
+      CommandLine cmd)
+      throws ApiException, JsonProcessingException {
     String fullTableName = json.getString(CliParams.FULL_NAME.getServerParam());
     TableInfo info =
         tablesApi.getTable(
@@ -242,6 +245,15 @@ private static String readTable(
               new GenerateTemporaryTableCredential()
                   .tableId(tableId)
                   .operation(TableOperation.READ));
+      boolean jsonOutput =
+          cmd.hasOption(CliUtils.OUTPUT)
+              && ("json".equals(cmd.getOptionValue(CliUtils.OUTPUT))
+                  || "jsonPretty".equals(cmd.getOptionValue(CliUtils.OUTPUT)));
+      if (jsonOutput) {
+        return objectWriter.writeValueAsString(
+            DeltaKernelUtils.readDeltaTableAsRecords(
+                info.getStorageLocation(), temporaryCredentials, maxResults));
+      }
       return DeltaKernelUtils.readDeltaTable(
           info.getStorageLocation(), temporaryCredentials, maxResults);
     } catch (Exception e) {

examples/cli/src/main/java/io/unitycatalog/cli/delta/DeltaKernelUtils.java

@@ -25,7 +25,9 @@
 import io.unitycatalog.client.model.ColumnInfo;
 import io.unitycatalog.client.model.TemporaryCredentials;
 import java.net.URI;
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -209,6 +211,32 @@ public static String readDeltaTable(
     }
   }
 
+  public static List<Map<String, String>> readDeltaTableAsRecords(
+      String tablePath, TemporaryCredentials temporaryCredentials, int maxResults) {
+    Engine engine = getEngine(URI.create(tablePath), temporaryCredentials);
+    try {
+      Table table = Table.forPath(engine, substituteSchemeForS3(tablePath));
+      Snapshot snapshot = table.getLatestSnapshot(engine);
+      StructType readSchema = snapshot.getSchema();
+      ScanBuilder scanBuilder = snapshot.getScanBuilder().withReadSchema(readSchema);
+      List<Row> rowData =
+          DeltaKernelReadUtils.readData(engine, readSchema, scanBuilder.build(), maxResults);
+
+      List<Map<String, String>> records = new ArrayList<>();
+      for (Row row : rowData) {
+        Map<String, String> record = new LinkedHashMap<>();
+        for (int colOrdinal = 0; colOrdinal < readSchema.length(); colOrdinal++) {
+          String colName = readSchema.at(colOrdinal).getName();
+          record.put(colName, DeltaKernelReadUtils.getValue(row, colOrdinal));
+        }
+        records.add(record);
+      }
+      return records;
+    } catch (Exception e) {
+      throw new IllegalArgumentException("Failed to read Delta table", e);
+    }
+  }
+
   // TODO : INTERVAL, CHAR and NULL, ARRAY, MAP, STRUCT
   public static StructType getSchema(List<ColumnInfo> columns) {
     StructType structType = new StructType();