Jsonl support

.gitignore

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

docs-src/main/userguide/importing_data.md

@@ -14,9 +14,10 @@ Tablesaw supports importing and exporting data to and from a variety of data typ
 | :----------------------------- | :----- | :----- |
 | CSV (and other delimited text) | Yes    | Yes    |
 | JSON                           | Yes    | Yes    |
+| JSONL                          | Yes    | Yes    |
 | RDBMS (via JDBC)               | Yes    |        |
 | Fixed Width Text               | Yes    | Yes    |
-| Excel                          | Yes    |        |
+| Excel                          | Yes    | Yes    |
 | HTML                           | Yes    | Yes    |
 
 ## Importing data
@@ -260,4 +261,4 @@ List<Table> tables=  xlsxReader.readMultiple(options);
 
 
 
-TODO
+TODO

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

@@ -0,0 +1,184 @@
+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 +1,127 @@
+package tech.tablesaw.io.jsonl;
+
+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 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 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) {
+    // no standard exists yet. taken from https://murex.rocks/types/jsonl.html#more-information
+    registry.registerExtension("jsonl", INSTANCE);
+    registry.registerMimeType("application/json-lines", INSTANCE);
+    registry.registerMimeType("application/jsonl", INSTANCE);
+    registry.registerMimeType("application/jsonlines", INSTANCE);
+    registry.registerMimeType("application/ldjson", INSTANCE);
+    registry.registerMimeType("application/ndjson", INSTANCE);
+    registry.registerMimeType("application/x-json-lines", INSTANCE);
+    registry.registerMimeType("application/x-jsonl", INSTANCE);
+    registry.registerMimeType("application/x-jsonlines", INSTANCE);
+    registry.registerMimeType("application/x-ldjson", INSTANCE);
+    registry.registerMimeType("application/x-ndjson", INSTANCE);
+    registry.registerMimeType("text/json-lines", INSTANCE);
+    registry.registerMimeType("text/jsonl", INSTANCE);
+    registry.registerMimeType("text/jsonlines", INSTANCE);
+    registry.registerMimeType("text/ldjson", INSTANCE);
+    registry.registerMimeType("text/ndjson", INSTANCE);
+    registry.registerMimeType("text/x-json-lines", INSTANCE);
+    registry.registerMimeType("text/x-jsonl", INSTANCE);
+    registry.registerMimeType("text/x-jsonlines", INSTANCE);
+    registry.registerMimeType("text/x-ldjson", INSTANCE);
+    registry.registerMimeType("text/x-ndjson", 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);
+    }
+  }
+}