Jsonl support

.gitignore

@@ -31,3 +31,6 @@ bin/
 nbproject/private/
 nbactions.xml
 nb-configuration.xml
+
+# VSCode
+.vscode/

json/src/main/java/tech/tablesaw/io/json/JsonWriteOptions.java

@@ -3,6 +3,7 @@
 import java.io.Writer;
 import tech.tablesaw.io.Destination;
 import tech.tablesaw.io.WriteOptions;
+import tech.tablesaw.io.jsonl.JsonlWriteOptions;
 
 public class JsonWriteOptions extends WriteOptions {
 

json/src/main/java/tech/tablesaw/io/jsonl/JsonlReadOptions.java

@@ -0,0 +1,186 @@
+package tech.tablesaw.io.jsonl;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Reader;
+import java.io.StringReader;
+import java.net.URL;
+import java.time.format.DateTimeFormatter;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Function;
+
+import tech.tablesaw.api.ColumnType;
+import tech.tablesaw.io.ReadOptions;
+import tech.tablesaw.io.Source;
+
+public class JsonlReadOptions extends ReadOptions {
+
+    private final String path;
+
+  protected JsonlReadOptions(Builder builder) {
+    super(builder);
+    this.path = builder.path;
+  }
+
+    public static Builder builder(Source source) {
+        return new Builder(source);
+    }
+
+    public static Builder builder(File file) {
+        return new Builder(file).tableName(file.getName());
+    }
+
+    public static Builder builder(String fileName) {
+        return new Builder(new File(fileName));
+    }
+
+    public static Builder builder(URL url) throws IOException {
+        return new Builder(url);
+    }
+
+    public static Builder builderFromFile(String fileName) {
+        return new Builder(new File(fileName));
+    }
+
+    public static Builder builderFromString(String contents) {
+        return new Builder(new StringReader(contents));
+    }
+
+    public static Builder builderFromUrl(String url) throws IOException {
+        return new Builder(new URL(url));
+    }
+
+    public static Builder builder(InputStream stream) {
+        return new Builder(stream);
+    }
+
+    public static Builder builder(Reader reader) {
+        return new Builder(reader);
+    }
+
+    public String path() {
+        return path;
+    }
+
+    public static class Builder extends ReadOptions.Builder {
+
+        private String path;
+
+        protected Builder(Source source) {
+            super(source);
+        }
+
+        protected Builder(URL url) throws IOException {
+            super(url);
+        }
+
+        public Builder(File file) {
+            super(file);
+        }
+
+        protected Builder(Reader reader) {
+            super(reader);
+        }
+
+        protected Builder(InputStream stream) {
+            super(stream);
+        }
+
+        @Override
+        public JsonlReadOptions build() {
+            return new JsonlReadOptions(this);
+        }
+
+        // Override super-class setters to return an instance of this class
+
+        @Override
+        public Builder header(boolean header) {
+            super.header(header);
+            return this;
+        }
+
+        @Override
+        public Builder tableName(String tableName) {
+            super.tableName(tableName);
+            return this;
+        }
+
+        @Override
+        public Builder sample(boolean sample) {
+            super.sample(sample);
+            return this;
+        }
+
+        @Override
+        public Builder dateFormat(DateTimeFormatter dateFormat) {
+            super.dateFormat(dateFormat);
+            return this;
+        }
+
+        @Override
+        public Builder timeFormat(DateTimeFormatter timeFormat) {
+            super.timeFormat(timeFormat);
+            return this;
+        }
+
+        @Override
+        public Builder dateTimeFormat(DateTimeFormatter dateTimeFormat) {
+            super.dateTimeFormat(dateTimeFormat);
+            return this;
+        }
+
+        @Override
+        public Builder locale(Locale locale) {
+            super.locale(locale);
+            return this;
+        }
+
+        @Override
+        public Builder missingValueIndicator(String... missingValueIndicators) {
+            super.missingValueIndicator(missingValueIndicators);
+            return this;
+        }
+
+        @Override
+        public Builder minimizeColumnSizes() {
+            super.minimizeColumnSizes();
+            return this;
+        }
+
+        /**
+         * @param path the JSON Pointer path used to select a sub-tree in the main
+         *             document
+         */
+        public Builder path(String path) {
+            this.path = path;
+            return this;
+        }
+
+        @Override
+        public Builder columnTypes(ColumnType[] columnTypes) {
+            super.columnTypes(columnTypes);
+            return this;
+        }
+
+        @Override
+        public Builder columnTypes(Function<String, ColumnType> columnTypeFunction) {
+            super.columnTypes(columnTypeFunction);
+            return this;
+        }
+
+        @Override
+        public Builder columnTypesPartial(Function<String, Optional<ColumnType>> columnTypeFunction) {
+            super.columnTypesPartial(columnTypeFunction);
+            return this;
+        }
+
+        @Override
+        public Builder columnTypesPartial(Map<String, ColumnType> columnTypeByName) {
+            super.columnTypesPartial(columnTypeByName);
+            return this;
+        }
+    }
+}

json/src/main/java/tech/tablesaw/io/jsonl/JsonlReader.java

@@ -0,0 +1,110 @@
+package tech.tablesaw.io.jsonl;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
+import com.github.wnameless.json.flattener.JsonFlattener;
+
+import tech.tablesaw.api.Table;
+import tech.tablesaw.io.DataReader;
+import tech.tablesaw.io.ReadOptions;
+import tech.tablesaw.io.ReaderRegistry;
+import tech.tablesaw.io.RuntimeIOException;
+import tech.tablesaw.io.Source;
+import tech.tablesaw.io.TableBuildingUtils;
+
+public class JsonlReader implements DataReader<JsonlReadOptions> {
+
+    private static final JsonlReader INSTANCE = new JsonlReader();
+    private static final ObjectMapper mapper = new ObjectMapper();
+
+    static {
+        register(Table.defaultReaderRegistry);
+    }
+
+    public static void register(ReaderRegistry registry) {
+        registry.registerExtension("jsonl", INSTANCE);
+        registry.registerMimeType("text/jsonl", INSTANCE);
+        registry.registerMimeType("application/jsonl+json", INSTANCE);
+        registry.registerOptions(JsonlReadOptions.class, INSTANCE);
+    }
+
+    @Override
+    public Table read(JsonlReadOptions options) {
+        ObjectReader stream = mapper.readerFor(JsonNode.class);
+        try {
+            Reader reader = options.source().createReader(null);
+            JsonParser parser = stream.createParser(reader);
+            Iterator<JsonNode> iter = stream.readValues(parser);
+            return convertObjects(iter, options);
+        } catch (IOException e) {
+            throw new RuntimeIOException(e);
+        }
+    }
+
+    private Table convertObjects(Iterator<JsonNode> iter, ReadOptions options) {
+        // flatten each object inside the array
+        StringBuilder result = new StringBuilder("[");
+        boolean first = true;
+        for (; iter.hasNext();) {
+            JsonNode rowObj = iter.next();
+            String flattenedRow = null;
+            try {
+                flattenedRow = JsonFlattener.flatten(mapper.writeValueAsString(rowObj));
+            } catch (JsonProcessingException e) {
+                throw new RuntimeIOException(e);
+            }
+            if (!first) {
+                result.append(",");
+            }
+            first = false;
+            result.append(flattenedRow);
+        }
+        String flattenedJsonString = result.append("]").toString();
+        JsonNode flattenedJsonObj = null;
+        try {
+            flattenedJsonObj = mapper.readTree(flattenedJsonString);
+        } catch (JsonProcessingException e) {
+            throw new RuntimeIOException(e);
+        }
+
+        Set<String> colNames = new LinkedHashSet<>();
+        for (JsonNode row : flattenedJsonObj) {
+            Iterator<String> fieldNames = row.fieldNames();
+            while (fieldNames.hasNext()) {
+                colNames.add(fieldNames.next());
+            }
+        }
+
+        List<String> columnNames = new ArrayList<>(colNames);
+        List<String[]> dataRows = new ArrayList<>();
+        for (JsonNode node : flattenedJsonObj) {
+            String[] arr = new String[columnNames.size()];
+            for (int i = 0; i < columnNames.size(); i++) {
+                if (node.has(columnNames.get(i))) {
+                    arr[i] = node.get(columnNames.get(i)).asText();
+                } else {
+                    arr[i] = null;
+                }
+            }
+            dataRows.add(arr);
+        }
+
+        return TableBuildingUtils.build(columnNames, dataRows, options);
+    }
+
+    @Override
+    public Table read(Source source) {
+        return read(JsonlReadOptions.builder(source).build());
+    }
+}

json/src/main/java/tech/tablesaw/io/jsonl/JsonlWriteOptions.java

@@ -0,0 +1,31 @@
+package tech.tablesaw.io.jsonl;
+
+import java.io.Writer;
+import tech.tablesaw.io.Destination;
+import tech.tablesaw.io.WriteOptions;
+
+public class JsonlWriteOptions extends WriteOptions {
+
+  private JsonlWriteOptions(Builder builder) {
+    super(builder);
+  }
+
+  public static Builder builder(Writer writer) {
+    return new Builder(new Destination(writer));
+  }
+
+  public static Builder builder(Destination destination) {
+    return new Builder(destination);
+  }
+
+  public static class Builder extends WriteOptions.Builder {
+
+    protected Builder(Destination destination) {
+      super(destination);
+    }
+
+    public JsonlWriteOptions build() {
+      return new JsonlWriteOptions(this);
+    }
+  }
+}