Similar to macro functions, for the RenderFilter store a temporary value

and throw a DeferredInvocationResolutionException if the render didn't
fully complete

Author: jasmith-hs

src/main/java/com/hubspot/jinjava/el/ext/eager/RenderFlatTempVariable.java

@@ -0,0 +1,40 @@
+package com.hubspot.jinjava.el.ext.eager;
+
+import com.hubspot.jinjava.objects.serialization.PyishBlockSetSerializable;
+import java.util.Objects;
+
+public class RenderFlatTempVariable implements PyishBlockSetSerializable {
+
+  private static final String CONTEXT_KEY_PREFIX = "__render_%d_temp_variable__";
+  private final String deferredResult;
+
+  public RenderFlatTempVariable(String deferredResult) {
+    this.deferredResult = deferredResult;
+  }
+
+  public static String getVarName(String result) {
+    return String.format(CONTEXT_KEY_PREFIX, Math.abs(result.hashCode() >> 1));
+  }
+
+  @Override
+  public String getBlockSetBody() {
+    return deferredResult;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    RenderFlatTempVariable that = (RenderFlatTempVariable) o;
+    return deferredResult.equals(that.deferredResult);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(deferredResult);
+  }
+}

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

@@ -4,6 +4,8 @@
 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.el.ext.DeferredInvocationResolutionException;
+import com.hubspot.jinjava.el.ext.eager.RenderFlatTempVariable;
 import com.hubspot.jinjava.interpret.JinjavaInterpreter;
 import java.util.Objects;
 import org.apache.commons.lang3.math.NumberUtils;
@@ -26,16 +28,29 @@ public String getName() {
 
   @Override
   public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
+    int numDeferredTokensStart = interpreter.getContext().getDeferredTokens().size();
+    String result;
     if (args.length > 0) {
       String firstArg = args[0];
-      return interpreter.renderFlat(
-        Objects.toString(var),
-        NumberUtils.toLong(
-          firstArg,
-          JinjavaConfig.newBuilder().build().getMaxOutputSize()
-        )
-      );
+      result =
+        interpreter.renderFlat(
+          Objects.toString(var),
+          NumberUtils.toLong(
+            firstArg,
+            JinjavaConfig.newBuilder().build().getMaxOutputSize()
+          )
+        );
+    } else {
+      result = interpreter.renderFlat(Objects.toString(var));
     }
-    return interpreter.renderFlat(Objects.toString(var));
+    if (interpreter.getContext().getDeferredTokens().size() > numDeferredTokensStart) {
+      String tempVarName = RenderFlatTempVariable.getVarName(result);
+      interpreter
+        .getContext()
+        .getParent()
+        .put(tempVarName, new RenderFlatTempVariable(result));
+      throw new DeferredInvocationResolutionException(tempVarName);
+    }
+    return result;
   }
 }

src/test/java/com/hubspot/jinjava/EagerTest.java

@@ -1669,4 +1669,11 @@ public void itHandlesDeferredContinueInForLoop() {
   public void itReconstructsFromedMacro() {
     expectedTemplateInterpreter.assertExpectedOutput("reconstructs-fromed-macro/test");
   }
+
+  @Test
+  public void itHandlesDeferredValueInRenderFilter() {
+    expectedTemplateInterpreter.assertExpectedOutput(
+      "handles-deferred-value-in-render-filter/test"
+    );
+  }
 }

src/test/resources/eager/handles-deferred-value-in-render-filter/test.expected.jinja

@@ -0,0 +1,9 @@
+{% set __render_524436216_temp_variable__ %}\
+Hi {{ filter:escape.filter(deferred, ____int3rpr3t3r____) }}\
+{% endset %}\
+{{ filter:escape_jinjava.filter(__render_524436216_temp_variable__, ____int3rpr3t3r____) }}
+
+{% set __render_524436216_temp_variable__ %}\
+Hi {{ filter:escape.filter(deferred, ____int3rpr3t3r____) }}\
+{% endset %}\
+{{ __render_524436216_temp_variable__ }}

src/test/resources/eager/handles-deferred-value-in-render-filter/test.jinja

@@ -0,0 +1,4 @@
+{% set foo = "Hi {{ deferred|escape }}" %}
+{{ foo|render|escape_jinjava }}
+
+{{ foo|render }}