Add filter which converts a map with camelCase attributes into one that also accepts snake_case keys

jasmith-hs · jasmith-hs · commit 4134c007a035 · 2023-03-15T11:14:58.000-04:00
diff --git a/src/main/java/com/hubspot/jinjava/lib/filter/AllowSnakeCaseFilter.java b/src/main/java/com/hubspot/jinjava/lib/filter/AllowSnakeCaseFilter.java
@@ -0,0 +1,43 @@
+package com.hubspot.jinjava.lib.filter;
+
+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.JinjavaInterpreter;
+import com.hubspot.jinjava.objects.collections.PyMap;
+import com.hubspot.jinjava.objects.collections.SizeLimitingPyMap;
+import com.hubspot.jinjava.objects.collections.SnakeCaseAccessibleMap;
+import java.util.Map;
+
+@JinjavaDoc(
+  value = "Allow keys on the provided camelCase map to be accessed using snake_case",
+  input = @JinjavaParam(
+    value = "map",
+    type = "dict",
+    desc = "The dict to make keys accessible using snake_case",
+    required = true
+  ),
+  snippets = { @JinjavaSnippet(code = "{{ {'fooBar': 'baz'}|allow_snake_case }}") }
+)
+public class AllowSnakeCaseFilter implements Filter {
+  public static final String NAME = "allow_snake_case";
+
+  @Override
+  public String getName() {
+    return NAME;
+  }
+
+  @Override
+  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
+    if (!(var instanceof Map)) {
+      return var;
+    }
+    Map<String, Object> map = (Map<String, Object>) var;
+    if (map instanceof PyMap) {
+      map = ((PyMap) map).toMap();
+    }
+    return new SnakeCaseAccessibleMap(
+      new SizeLimitingPyMap(map, interpreter.getConfig().getMaxMapSize())
+    );
+  }
+}
diff --git a/src/main/java/com/hubspot/jinjava/lib/filter/FilterLibrary.java b/src/main/java/com/hubspot/jinjava/lib/filter/FilterLibrary.java
@@ -32,6 +32,7 @@ protected void registerDefaults() {
     registerClasses(
       AbsFilter.class,
       AddFilter.class,
+      AllowSnakeCaseFilter.class,
       AttrFilter.class,
       Base64DecodeFilter.class,
       Base64EncodeFilter.class,
diff --git a/src/main/java/com/hubspot/jinjava/objects/collections/SnakeCaseAccessibleMap.java b/src/main/java/com/hubspot/jinjava/objects/collections/SnakeCaseAccessibleMap.java
@@ -0,0 +1,43 @@
+package com.hubspot.jinjava.objects.collections;
+
+import com.google.common.base.CaseFormat;
+import com.hubspot.jinjava.lib.filter.AllowSnakeCaseFilter;
+import com.hubspot.jinjava.objects.serialization.PyishSerializable;
+import java.io.IOException;
+import java.util.Map;
+
+public class SnakeCaseAccessibleMap extends PyMap implements PyishSerializable {
+
+  public SnakeCaseAccessibleMap(Map<String, Object> map) {
+    super(map);
+  }
+
+  @Override
+  public Object get(Object key) {
+    Object result = super.get(key);
+    if (result == null && key instanceof String) {
+      return getWithCamelCase((String) key);
+    }
+    return result;
+  }
+
+  private Object getWithCamelCase(String key) {
+    if (key == null) {
+      return null;
+    }
+    if (key.indexOf('_') == -1) {
+      return null;
+    }
+    return super.get(CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, key));
+  }
+
+  @SuppressWarnings("unchecked")
+  @Override
+  public <T extends Appendable & CharSequence> T appendPyishString(T appendable)
+    throws IOException {
+    return (T) appendable
+      .append(PyishSerializable.writeValueAsString(toMap()))
+      .append('|')
+      .append(AllowSnakeCaseFilter.NAME);
+  }
+}
diff --git a/src/test/java/com/hubspot/jinjava/lib/filter/AllowSnakeCaseFilterTest.java b/src/test/java/com/hubspot/jinjava/lib/filter/AllowSnakeCaseFilterTest.java
@@ -0,0 +1,28 @@
+package com.hubspot.jinjava.lib.filter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.hubspot.jinjava.BaseInterpretingTest;
+import com.hubspot.jinjava.objects.serialization.PyishObjectMapper;
+import org.junit.Test;
+
+public class AllowSnakeCaseFilterTest extends BaseInterpretingTest {
+
+  @Test
+  public void itDoesNotChangeNonMaps() {
+    assertThat(interpreter.render("{{ 'fooBar'|allow_snake_case }}")).isEqualTo("fooBar");
+  }
+
+  @Test
+  public void itMakesMapKeysAccessibleWithSnakeCase() {
+    assertThat(interpreter.render("{{ ({'fooBar': 'foo'}|allow_snake_case).foo_bar }}"))
+      .isEqualTo("foo");
+  }
+
+  @Test
+  public void itReserializesAsSnakeCaseAccessibleMap() {
+    interpreter.render("{% set map = {'fooBar': 'foo'}|allow_snake_case %}");
+    assertThat(PyishObjectMapper.getAsPyishString(interpreter.getContext().get("map")))
+      .isEqualTo("{'fooBar': 'foo'} |allow_snake_case");
+  }
+}
