Json stdout

app/gui/src/main/java/org/mobilitydata/gtfsvalidator/app/gui/GtfsValidatorApp.java

@@ -35,6 +35,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Optional;
 import java.util.ResourceBundle;
 import javax.swing.BorderFactory;
 import javax.swing.Box;
@@ -371,6 +372,7 @@ private void runValidation() {
   private ValidationRunnerConfig buildConfig() throws URISyntaxException {
     ValidationRunnerConfig.Builder config = ValidationRunnerConfig.builder();
     config.setPrettyJson(true);
+    config.setStdoutOutput(false);
 
     String gtfsInput = gtfsInputField.getText();
     if (gtfsInput.isBlank()) {
@@ -386,7 +388,7 @@ private ValidationRunnerConfig buildConfig() throws URISyntaxException {
     if (outputDirectory.isBlank()) {
       throw new IllegalStateException("outputDirectoryField is blank");
     }
-    config.setOutputDirectory(Path.of(outputDirectory));
+    config.setOutputDirectory(Optional.of(Path.of(outputDirectory)));
 
     Object numThreads = numThreadsSpinner.getValue();
     if (numThreads instanceof Integer) {

app/gui/src/main/java/org/mobilitydata/gtfsvalidator/app/gui/ValidationDisplay.java

@@ -18,9 +18,9 @@ void handleResult(ValidationRunnerConfig config, ValidationRunner.Status status)
       handleError();
     }
 
-    Path reportPath = config.htmlReportPath();
+    Path reportPath = config.htmlReportPath().orElse(null);
     if (status == ValidationRunner.Status.SYSTEM_ERRORS) {
-      reportPath = config.systemErrorsReportPath();
+      reportPath = config.systemErrorsReportPath().orElse(null);
     }
 
     try {

app/gui/src/test/java/org/mobilitydata/gtfsvalidator/app/gui/GtfsValidatorAppTest.java

@@ -66,7 +66,7 @@ public void testValidationConfig() throws URISyntaxException {
 
     ValidationRunnerConfig config = configCaptor.getValue();
     assertThat(config.gtfsSource()).isEqualTo(new URI("http://transit/gtfs.zip"));
-    assertThat(config.outputDirectory()).isEqualTo(Path.of("/path/to/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/path/to/output"));
     assertThat(config.numThreads()).isEqualTo(1);
     assertThat(config.countryCode().isUnknown()).isTrue();
   }
@@ -84,7 +84,7 @@ public void testValidationConfigWithAdvancedOptions() throws URISyntaxException
 
     ValidationRunnerConfig config = configCaptor.getValue();
     assertThat(config.gtfsSource()).isEqualTo(new URI("http://transit/gtfs.zip"));
-    assertThat(config.outputDirectory()).isEqualTo(Path.of("/path/to/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/path/to/output"));
     assertThat(config.numThreads()).isEqualTo(5);
     assertThat(config.countryCode().getCountryCode()).isEqualTo("US");
   }

cli/build.gradle

@@ -38,6 +38,9 @@ shadowJar {
         // from minimization.
         exclude(project(':main'))
         exclude(dependency(libs.httpclient5.get().toString()))
+        // Keep SLF4J implementation to avoid warnings
+        // Note that SLF4J comes from some transitive dependencies
+        exclude(dependency('org.slf4j:slf4j-jdk14'))
     }
     // Change the JAR name from 'main' to 'gtfs-validator'
     archiveBaseName = rootProject.name
@@ -55,6 +58,7 @@ dependencies {
     implementation libs.flogger
     implementation libs.flogger.system.backend
     implementation libs.guava
+    implementation libs.slf4j.jul
 
     testImplementation libs.junit
     testImplementation libs.truth

cli/src/main/java/org/mobilitydata/gtfsvalidator/cli/Arguments.java

@@ -23,6 +23,7 @@
 import java.nio.file.Path;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
+import java.util.Optional;
 import org.mobilitydata.gtfsvalidator.input.CountryCode;
 import org.mobilitydata.gtfsvalidator.runner.ValidationRunnerConfig;
 
@@ -38,8 +39,7 @@ public class Arguments {
 
   @Parameter(
       names = {"-o", "--output_base"},
-      description = "Base directory to store the outputs",
-      required = true)
+      description = "Base directory to store the outputs (required if not using --stdout)")
   private String outputBase;
 
   @Parameter(
@@ -110,6 +110,11 @@ public class Arguments {
       description = "Skips check for new validator version")
   private boolean skipValidatorUpdate = false;
 
+  @Parameter(
+      names = {"--stdout"},
+      description = "Output JSON report to stdout instead of writing to files (conflicts with -o)")
+  private boolean stdoutOutput = false;
+
   ValidationRunnerConfig toConfig() throws URISyntaxException {
     ValidationRunnerConfig.Builder builder = ValidationRunnerConfig.builder();
     if (input != null) {
@@ -121,7 +126,10 @@ ValidationRunnerConfig toConfig() throws URISyntaxException {
       }
     }
     if (outputBase != null) {
-      builder.setOutputDirectory(Path.of(outputBase));
+      builder.setOutputDirectory(Optional.of(Path.of(outputBase)));
+    } else if (stdoutOutput) {
+      // When using stdout, no output directory is needed
+      builder.setOutputDirectory(Optional.empty());
     }
     if (countryCode != null) {
       builder.setCountryCode(CountryCode.forStringOrUnknown(countryCode));
@@ -141,6 +149,7 @@ ValidationRunnerConfig toConfig() throws URISyntaxException {
     builder.setNumThreads(numThreads);
     builder.setPrettyJson(pretty);
     builder.setSkipValidatorUpdate(skipValidatorUpdate);
+    builder.setStdoutOutput(stdoutOutput);
     return builder.build();
   }
 
@@ -160,6 +169,10 @@ public boolean getExportNoticeSchema() {
     return exportNoticeSchema;
   }
 
+  public boolean getStdoutOutput() {
+    return stdoutOutput;
+  }
+
   /**
    * @return true if CLI parameter combination is legal, otherwise return false
    */
@@ -185,6 +198,16 @@ public boolean validate() {
       return false;
     }
 
+    if (stdoutOutput && outputBase != null) {
+      logger.atSevere().log("Cannot use --stdout with --output_base. Use one or the other.");
+      return false;
+    }
+
+    if (outputBase == null && !stdoutOutput) {
+      logger.atSevere().log("Must provide either --output_base or --stdout");
+      return false;
+    }
+
     return true;
   }
 

cli/src/test/java/org/mobilitydata/gtfsvalidator/cli/ArgumentsTest.java

@@ -18,10 +18,10 @@
 
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth8.assertThat;
-import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 import com.beust.jcommander.JCommander;
-import com.beust.jcommander.ParameterException;
 import java.io.File;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -45,7 +45,7 @@ public void shortNameShouldInitializeArguments() throws URISyntaxException {
     new JCommander(underTest).parse(commandLineArgumentAsStringArray);
     ValidationRunnerConfig config = underTest.toConfig();
     assertThat(config.gtfsSource()).isEqualTo(toFileUri("/tmp/gtfs.zip"));
-    assertThat((Object) config.outputDirectory()).isEqualTo(Path.of("/tmp/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/tmp/output"));
     assertThat(config.countryCode()).isEqualTo(CountryCode.forStringOrUnknown("au"));
     assertThat(config.numThreads()).isEqualTo(4);
     assertThat(config.validationReportFileName()).matches("report.json");
@@ -72,7 +72,7 @@ public void shortNameShouldInitializeArguments_url() throws URISyntaxException {
     new JCommander(underTest).parse(commandLineArgumentAsStringArray);
     ValidationRunnerConfig config = underTest.toConfig();
     assertThat(config.gtfsSource()).isEqualTo(new URI("http://host/gtfs.zip"));
-    assertThat((Object) config.outputDirectory()).isEqualTo(Path.of("/tmp/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/tmp/output"));
     assertThat(config.countryCode()).isEqualTo(CountryCode.forStringOrUnknown("au"));
     assertThat(config.numThreads()).isEqualTo(4);
     assertThat(config.storageDirectory()).hasValue(Path.of("/tmp/storage"));
@@ -95,7 +95,7 @@ public void longNameShouldInitializeArguments() throws URISyntaxException {
     new JCommander(underTest).parse(commandLineArgumentAsStringArray);
     ValidationRunnerConfig config = underTest.toConfig();
     assertThat(config.gtfsSource()).isEqualTo(toFileUri("/tmp/gtfs.zip"));
-    assertThat((Object) config.outputDirectory()).isEqualTo(Path.of("/tmp/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/tmp/output"));
     assertThat(config.countryCode()).isEqualTo(CountryCode.forStringOrUnknown("ca"));
     assertThat(config.numThreads()).isEqualTo(4);
     assertThat(config.validationReportFileName()).matches("report.json");
@@ -131,7 +131,7 @@ public void longNameShouldInitializeArguments_url() throws URISyntaxException {
     new JCommander(underTest).parse(commandLineArgumentAsStringArray);
     ValidationRunnerConfig config = underTest.toConfig();
     assertThat(config.gtfsSource()).isEqualTo(new URI("http://host/gtfs.zip"));
-    assertThat((Object) config.outputDirectory()).isEqualTo(Path.of("/tmp/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/tmp/output"));
     assertThat(config.countryCode()).isEqualTo(CountryCode.forStringOrUnknown("ca"));
     assertThat(config.numThreads()).isEqualTo(4);
     assertThat(config.storageDirectory()).hasValue(Path.of("/tmp/storage"));
@@ -152,7 +152,7 @@ public void numThreadsShouldHaveDefaultValueIfNotProvided() throws URISyntaxExce
     new JCommander(underTest).parse(commandLineArgumentAsStringArray);
     ValidationRunnerConfig config = underTest.toConfig();
     assertThat(config.gtfsSource()).isEqualTo(toFileUri("/tmp/gtfs.zip"));
-    assertThat((Object) config.outputDirectory()).isEqualTo(Path.of("/tmp/output"));
+    assertThat(config.outputDirectory()).hasValue(Path.of("/tmp/output"));
     assertThat(config.countryCode()).isEqualTo(CountryCode.forStringOrUnknown("ca"));
     assertThat(config.numThreads()).isEqualTo(1);
   }
@@ -182,7 +182,7 @@ public void noUrlNoInput_long_isNotValid() {
 
   @Test
   public void noArguments_isNotValid() {
-    assertThrows(ParameterException.class, () -> validateArguments(new String[] {}));
+    assertThat(validateArguments(new String[] {})).isFalse();
   }
 
   @Test
@@ -259,4 +259,39 @@ public void exportNoticesSchema_schemaAndValidation() {
     assertThat(args.getExportNoticeSchema()).isTrue();
     assertThat(args.abortAfterNoticeSchemaExport()).isFalse();
   }
+
+  @Test
+  public void testStdoutOutput() {
+    String[] commandLineArgumentAsStringArray = {"--input", "test.zip", "--stdout"};
+
+    Arguments args = new Arguments();
+    new JCommander(args).parse(commandLineArgumentAsStringArray);
+
+    assertTrue(args.validate());
+    assertTrue(args.getStdoutOutput());
+  }
+
+  @Test
+  public void testStdoutOutputWithOutputBaseConflict() {
+    String[] commandLineArgumentAsStringArray = {
+      "--input", "test.zip",
+      "--output_base", "/tmp/output",
+      "--stdout"
+    };
+
+    Arguments args = new Arguments();
+    new JCommander(args).parse(commandLineArgumentAsStringArray);
+
+    assertFalse(args.validate());
+  }
+
+  @Test
+  public void testStdoutOutputWithoutInput() {
+    String[] commandLineArgumentAsStringArray = {"--stdout"};
+
+    Arguments args = new Arguments();
+    new JCommander(args).parse(commandLineArgumentAsStringArray);
+
+    assertFalse(args.validate());
+  }
 }

docs/USAGE.md

@@ -26,6 +26,7 @@
 | `-e`       | `--system_errors_report_name` | Optional               | Name of the system errors report (including `.json` extension).                                                                                                                                                                                               |
 | `-n`       | `--export_notices_schema`     | Optional               | Export notice schema as a json file.                                                                                                                                                                                                                          |
 | `-p`       | `--pretty`                    | Optional               | Pretty JSON validation report. If specified, the JSON validation report will be printed using JSON Pretty print. This does not impact data parsing.                                                                                                           |
+| `--stdout` | `--stdout`                    | Optional               | Output JSON report to stdout instead of writing to files. Use with `-i` or `-u` but not with `-o`. Enables piping to tools like `jq`.                                                                                                                          |
 | `-d`       | `--date`                      | Optional               | The date used to validate the feed for time-based rules, e.g feed_expiration_30_days, in ISO_LOCAL_DATE format like '2001-01-30'. By default, the current date is used.                                                                                       |
 | `-svu`     | `--skip_validator_update`     | Optional               | Skip GTFS version validation update check. If specified, the GTFS version validation will be skipped. By default, the GTFS version validation will be performed.                                                                                              |                                              
 
@@ -61,6 +62,34 @@ java -jar gtfs-validator-v2.0.jar -u https://url/to/dataset.zip -o relative/outp
  1. Validate the GTFS data and output the results to the directory located at `relative/output/path`. Validation results are exported to JSON by default.
 Please note that since downloading will take time, we recommend validating repeatedly on a local file.
 
+## via stdout output (for scripting and piping)
+
+The `--stdout` option outputs JSON directly to stdout instead of writing files, making it ideal for scripting and piping to other tools.
+
+### Basic stdout usage
+``` 
+java -jar gtfs-validator-v2.0.jar -i relative/path/to/dataset.zip --stdout
+```
+
+### Pipe to jq for processing
+``` 
+java -jar gtfs-validator-v2.0.jar -i relative/path/to/dataset.zip --stdout | jq '.summary.validationTimeSeconds'
+```
+
+### Pretty JSON output to stdout
+``` 
+java -jar gtfs-validator-v2.0.jar -i relative/path/to/dataset.zip --stdout --pretty
+```
+
+### URL-based input with stdout
+``` 
+java -jar gtfs-validator-v2.0.jar -u https://url/to/dataset.zip --stdout
+```
+
+⚠️ Note that `--stdout` cannot be used with `-o` or `--output_base`. Use one or the other.
+
+⚠️ When using `--stdout`, all system errors and logging output are suppressed to ensure clean JSON output. Only severe-level log messages (hard crashes) will appear on stderr.
+
 ## via GitHub Actions - Run the validator on any gtfs archive available on a public url
 
 1. [Fork this repository](https://docs.github.com/en/github/getting-started-with-github/fork-a-repo)

gradle/libs.versions.toml

@@ -70,4 +70,5 @@ jetbrains-annotations = { module = "org.jetbrains:annotations", version.ref = "j
 aspectjrt = { module = "org.aspectj:aspectjrt", version.ref = "aspectjrt" }
 aspectjrt-weaver = { module = "org.aspectj:aspectjweaver", version.ref = "aspectjrtweaver" }
 findbugs = { module = "com.google.code.findbugs:jsr305", version.ref = "findbugs" }
-jackson-databind = { module = "com.fasterxml.jackson.core:jackson-databind", version.ref = "jacksonDatabind" }
+jackson-databind = { module = "com.fasterxml.jackson.core:jackson-databind", version.ref = "jacksonDatabind" }
+slf4j-jul = { module = "org.slf4j:slf4j-jdk14", version = "1.7.25" }

main/src/main/java/org/mobilitydata/gtfsvalidator/reportsummary/JsonReportSummaryGenerator.java

@@ -31,7 +31,9 @@ public JsonReportSummaryGenerator(
             date,
             config != null ? config.gtfsSource().toString() : null,
             config != null ? config.numThreads() : 0,
-            config != null ? config.outputDirectory().toString() : null,
+            config != null && config.outputDirectory().isPresent()
+                ? config.outputDirectory().get().toString()
+                : null,
             config != null ? config.systemErrorsReportFileName() : null,
             config != null ? config.validationReportFileName() : null,
             config != null ? config.htmlReportFileName() : null,