Add function and filter to convert string to date (#608)

* Add strtodate function and filter

* Register function, add tests

* Add jinjava doc

* prettier

* convert to string

Co-authored-by: Liam Harwood <[email protected]>

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

@@ -58,6 +58,7 @@ protected void registerDefaults() {
       MinusTimeFilter.class,
       BetweenTimesFilter.class,
       StringToTimeFilter.class,
+      StringToDateFilter.class,
       UnionFilter.class,
       IntersectFilter.class,
       DifferenceFilter.class,

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

@@ -0,0 +1,49 @@
+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.interpret.TemplateSyntaxException;
+import com.hubspot.jinjava.lib.fn.Functions;
+
+@JinjavaDoc(
+  value = "Converts a date string and date format to a date object",
+  input = @JinjavaParam(value = "dateString", desc = "Date string", required = true),
+  params = {
+    @JinjavaParam(
+      value = "dateFormat",
+      desc = "Format of the date string",
+      required = true
+    )
+  },
+  snippets = { @JinjavaSnippet(code = "{{ '3/3/21'|strtodate('M/d/yy') }}") }
+)
+public class StringToDateFilter implements Filter {
+
+  @Override
+  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
+    if (args.length < 1) {
+      throw new TemplateSyntaxException(
+        interpreter,
+        getName(),
+        "requires 1 argument (date format string)"
+      );
+    }
+
+    if (var == null) {
+      return null;
+    }
+
+    if (!(var instanceof String)) {
+      var = String.valueOf(var);
+    }
+
+    return Functions.stringToDate((String) var, args[0]);
+  }
+
+  @Override
+  public String getName() {
+    return "strtodate";
+  }
+}

src/main/java/com/hubspot/jinjava/lib/fn/FunctionLibrary.java

@@ -67,6 +67,16 @@ protected void registerDefaults() {
         String.class
       )
     );
+    register(
+      new ELFunctionDefinition(
+        "",
+        "strtodate",
+        Functions.class,
+        Functions.STRING_TO_DATE_FUNCTION,
+        String.class,
+        String.class
+      )
+    );
 
     register(new ELFunctionDefinition("", "super", Functions.class, "renderSuperBlock"));
 

src/main/java/com/hubspot/jinjava/lib/fn/Functions.java

@@ -16,6 +16,7 @@
 import com.hubspot.jinjava.util.LengthLimitingStringBuilder;
 import java.time.DateTimeException;
 import java.time.Instant;
+import java.time.LocalDate;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
@@ -31,6 +32,7 @@
 
 public class Functions {
   public static final String STRING_TO_TIME_FUNCTION = "stringToTime";
+  public static final String STRING_TO_DATE_FUNCTION = "stringToDate";
 
   public static final int RANGE_LIMIT = 1000;
 
@@ -241,6 +243,56 @@ public static PyishDate stringToTime(String datetimeString, String datetimeForma
     }
   }
 
+  @JinjavaDoc(
+    value = "converts a string and date format into a date object",
+    params = {
+      @JinjavaParam(value = "dateString", type = "string", desc = "date as string"),
+      @JinjavaParam(
+        value = "dateFormat",
+        type = "string",
+        desc = "format of the date string"
+      )
+    }
+  )
+  public static PyishDate stringToDate(String dateString, String dateFormat) {
+    if (dateString == null) {
+      return null;
+    }
+
+    if (dateFormat == null) {
+      throw new InterpretException(
+        String.format("%s() requires non-null date format", STRING_TO_DATE_FUNCTION)
+      );
+    }
+
+    try {
+      String convertedFormat = StrftimeFormatter.toJavaDateTimeFormat(dateFormat);
+      return new PyishDate(
+        LocalDate
+          .parse(dateString, DateTimeFormatter.ofPattern(convertedFormat))
+          .atTime(0, 0)
+          .toInstant(ZoneOffset.UTC)
+      );
+    } catch (DateTimeParseException e) {
+      throw new InterpretException(
+        String.format(
+          "%s() could not match date input %s with date format %s",
+          STRING_TO_DATE_FUNCTION,
+          dateString,
+          dateFormat
+        )
+      );
+    } catch (IllegalArgumentException e) {
+      throw new InterpretException(
+        String.format(
+          "%s() requires valid date format, was %s",
+          STRING_TO_DATE_FUNCTION,
+          dateFormat
+        )
+      );
+    }
+  }
+
   private static final int DEFAULT_TRUNCATE_LENGTH = 255;
   private static final String DEFAULT_END = "...";
 

src/test/java/com/hubspot/jinjava/lib/fn/StringToDateFunctionTest.java

@@ -0,0 +1,50 @@
+package com.hubspot.jinjava.lib.fn;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.hubspot.jinjava.interpret.InterpretException;
+import com.hubspot.jinjava.objects.date.PyishDate;
+import java.time.LocalDate;
+import java.time.ZoneOffset;
+import org.junit.Test;
+
+public class StringToDateFunctionTest {
+
+  @Test
+  public void itConvertsStringToDate() {
+    String dateString = "3/4/21";
+    String format = "M/d/yy";
+    PyishDate expected = new PyishDate(
+      LocalDate.of(2021, 3, 4).atTime(0, 0).toInstant(ZoneOffset.UTC)
+    );
+    assertThat(Functions.stringToDate(dateString, format)).isEqualTo(expected);
+  }
+
+  @Test
+  public void itFailsOnInvalidFormat() {
+    String dateString = "3/4/21";
+    String format = "blah blah";
+
+    assertThatThrownBy(() -> Functions.stringToDate(dateString, format))
+      .isInstanceOf(InterpretException.class);
+  }
+
+  @Test
+  public void itFailsOnTimeFormatMismatch() {
+    String dateString = "3/4/21";
+    String format = "M/d/yyyy";
+
+    assertThatThrownBy(() -> Functions.stringToDate(dateString, format))
+      .isInstanceOf(InterpretException.class);
+  }
+
+  @Test
+  public void itFailsOnNullDatetimeFormat() {
+    String dateString = "3/4/21";
+    String format = null;
+
+    assertThatThrownBy(() -> Functions.stringToDate(dateString, format))
+      .isInstanceOf(InterpretException.class);
+  }
+}