toyaml/fromyaml filters, almost the same as tojson/fromjson using jackson

pom.xml

@@ -118,6 +118,11 @@
       <groupId>com.fasterxml.jackson.core</groupId>
       <artifactId>jackson-core</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.fasterxml.jackson.dataformat</groupId>
+      <artifactId>jackson-dataformat-yaml</artifactId>
+    </dependency>
+
     <dependency>
       <groupId>ch.obermuhlner</groupId>
       <artifactId>big-math</artifactId>

src/main/java/com/hubspot/jinjava/lib/filter/FilterLibrary.java

@@ -108,7 +108,9 @@ protected void registerDefaults() {
       WordCountFilter.class,
       WordWrapFilter.class,
       ToJsonFilter.class,
-      FromJsonFilter.class
+      FromJsonFilter.class,
+      ToYamlFilter.class,
+      FromYamlFilter.class
     );
   }
 

src/main/java/com/hubspot/jinjava/lib/filter/FromYamlFilter.java

@@ -0,0 +1,44 @@
+package com.hubspot.jinjava.lib.filter;
+
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
+import com.hubspot.jinjava.doc.annotations.JinjavaParam;
+import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
+import com.hubspot.jinjava.interpret.InvalidInputException;
+import com.hubspot.jinjava.interpret.InvalidReason;
+import com.hubspot.jinjava.interpret.JinjavaInterpreter;
+import java.io.IOException;
+
+@JinjavaDoc(
+  value = "Converts YAML string to Object",
+  input = @JinjavaParam(
+    value = "string",
+    desc = "YAML String to write to object",
+    required = true
+  ),
+  snippets = { @JinjavaSnippet(code = "{{object|fromYaml}}") }
+)
+public class FromYamlFilter implements Filter {
+  private static final YAMLMapper OBJECT_MAPPER = new YAMLMapper();
+
+  @Override
+  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
+    if (var == null) {
+      return null;
+    }
+
+    if (!(var instanceof String)) {
+      throw new InvalidInputException(interpreter, this, InvalidReason.STRING);
+    }
+    try {
+      return OBJECT_MAPPER.readValue((String) var, Object.class);
+    } catch (IOException e) {
+      throw new InvalidInputException(interpreter, this, InvalidReason.JSON_READ);
+    }
+  }
+
+  @Override
+  public String getName() {
+    return "fromyaml";
+  }
+}

src/main/java/com/hubspot/jinjava/lib/filter/ToYamlFilter.java

@@ -0,0 +1,39 @@
+package com.hubspot.jinjava.lib.filter;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
+import com.hubspot.jinjava.doc.annotations.JinjavaParam;
+import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
+import com.hubspot.jinjava.interpret.InvalidInputException;
+import com.hubspot.jinjava.interpret.InvalidReason;
+import com.hubspot.jinjava.interpret.JinjavaInterpreter;
+
+@JinjavaDoc(
+  value = "Writes object as a YAML string",
+  input = @JinjavaParam(
+    value = "object",
+    desc = "Object to write to YAML",
+    required = true
+  ),
+  snippets = { @JinjavaSnippet(code = "{{object|toyaml}}") }
+)
+public class ToYamlFilter implements Filter {
+  private static final YAMLMapper OBJECT_MAPPER = new YAMLMapper()
+  .disable(YAMLGenerator.Feature.WRITE_DOC_START_MARKER);
+
+  @Override
+  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
+    try {
+      return OBJECT_MAPPER.writeValueAsString(var);
+    } catch (JsonProcessingException e) {
+      throw new InvalidInputException(interpreter, this, InvalidReason.JSON_WRITE);
+    }
+  }
+
+  @Override
+  public String getName() {
+    return "toyaml";
+  }
+}

src/test/java/com/hubspot/jinjava/lib/filter/FromYamlFilterTest.java

@@ -0,0 +1,93 @@
+package com.hubspot.jinjava.lib.filter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.google.common.collect.ImmutableMap;
+import com.hubspot.jinjava.BaseInterpretingTest;
+import com.hubspot.jinjava.interpret.InvalidInputException;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+
+public class FromYamlFilterTest extends BaseInterpretingTest {
+  private FromYamlFilter filter;
+
+  @Before
+  public void setup() {
+    filter = new FromYamlFilter();
+  }
+
+  @Test(expected = InvalidInputException.class)
+  public void itFailsWhenParameterIsNotString() {
+    Integer json = 456;
+
+    filter.filter(json, interpreter);
+  }
+
+  @Test(expected = InvalidInputException.class)
+  public void itFailsWhenYamlIsInvalid() {
+    String json = "a: b:";
+
+    filter.filter(json, interpreter);
+  }
+
+  @Test
+  public void itRendersTrivialYamlObject() {
+    String trivialYamlObject = "a: 100\n" + "b: 200";
+
+    Map<String, Object> vars = ImmutableMap.of("test", trivialYamlObject);
+    String template = "{% set obj = test | fromyaml %}{{ obj.a }} {{ obj.b }}";
+    String renderedJinjava = jinjava.render(template, vars);
+
+    assertThat(renderedJinjava).isEqualTo("100 200");
+  }
+
+  @Test
+  public void itRendersTrivialYamlArray() {
+    String trivialYamlArray = "- one\n" + "- two\n" + "- three";
+
+    Map<String, Object> vars = ImmutableMap.of("test", trivialYamlArray);
+    String template =
+      "{% set obj = test | fromyaml %}{{ obj[0] }} {{ obj[1] }} {{ obj[2] }}";
+    String renderedJinjava = jinjava.render(template, vars);
+
+    assertThat(renderedJinjava).isEqualTo("one two three");
+  }
+
+  @Test
+  public void itRendersNestedObjectYaml() {
+    String nestedObject =
+      "first: 1\n" + "nested:\n" + "  second: string\n" + "  third: 4";
+
+    Map<String, Object> vars = ImmutableMap.of("test", nestedObject);
+    String template =
+      "{% set obj = test | fromyaml %}{{ obj.first }} {{ obj.nested.second }} {{ obj.nested.third }}";
+    String renderedJinjava = jinjava.render(template, vars);
+
+    assertThat(renderedJinjava).isEqualTo("1 string 4");
+  }
+
+  @Test
+  public void itRendersNestedYamlWithArray() {
+    String nestedObjectWithArray =
+      "a:\n" + "  b:\n" + "    c:\n" + "    - 1\n" + "    - 2\n" + "    - 3";
+
+    Map<String, Object> vars = ImmutableMap.of("test", nestedObjectWithArray);
+    String template = "{% set obj = test | fromyaml %}{{ obj.a.b.c }}";
+    String renderedJinjava = jinjava.render(template, vars);
+
+    assertThat(renderedJinjava).isEqualTo("[1, 2, 3]");
+  }
+
+  @Test
+  public void itRendersArrayOfObjects() {
+    String arrayOfObjects = "- a: 1\n" + "- a: 2\n" + "- a: 3";
+
+    Map<String, Object> vars = ImmutableMap.of("test", arrayOfObjects);
+    String template =
+      "{% set obj = test | fromyaml %}{{ obj[0].a }} {{ obj[1].a }} {{ obj[2].a }}";
+    String renderedJinjava = jinjava.render(template, vars);
+
+    assertThat(renderedJinjava).isEqualTo("1 2 3");
+  }
+}

src/test/java/com/hubspot/jinjava/lib/filter/ToYamlFilterTest.java

@@ -0,0 +1,33 @@
+package com.hubspot.jinjava.lib.filter;
+
+import static org.assertj.core.api.Java6Assertions.assertThat;
+
+import com.hubspot.jinjava.BaseInterpretingTest;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ToYamlFilterTest extends BaseInterpretingTest {
+  private ToYamlFilter filter;
+
+  @Before
+  public void setup() {
+    filter = new ToYamlFilter();
+  }
+
+  @Test
+  public void itWritesObjectAsString() {
+    int[] testArray = new int[] { 4, 1, 2 };
+    assertThat(filter.filter(testArray, interpreter))
+      .isEqualTo("- 4\n" + "- 1\n" + "- 2\n");
+
+    Map<String, Object> testMap = new HashMap<>();
+    testMap.put("testArray", testArray);
+    testMap.put("testString", "testString");
+    assertThat(filter.filter(testMap, interpreter))
+      .isEqualTo(
+        "testArray:\n" + "- 4\n" + "- 1\n" + "- 2\n" + "testString: \"testString\"\n"
+      );
+  }
+}