Remembering previously entered values (auto-fill)

resources/org/javarosa/xform/parse/last-saved-blank.xml

@@ -0,0 +1,22 @@
+<h:html
+    xmlns:h="http://www.w3.org/1999/xhtml"
+    xmlns="http://www.w3.org/2002/xforms">
+
+    <h:head>
+        <h:title>Form with last-saved instance (blank)</h:title>
+        <model>
+            <instance>
+                <data>
+                    <item/>
+                </data>
+            </instance>
+            <instance id="last-saved" src="jr://instance/last-saved"/>
+            <bind nodeset="/data/item" type="string"/>
+            <setvalue event="xforms-ready" ref="/data/item" value="instance('last-saved')/data/item"/>
+        </model>
+    </h:head>
+
+    <h:body>
+    </h:body>
+
+</h:html>

resources/org/javarosa/xform/parse/last-saved-filled.xml

@@ -0,0 +1,22 @@
+<h:html
+    xmlns:h="http://www.w3.org/1999/xhtml"
+    xmlns="http://www.w3.org/2002/xforms">
+
+    <h:head>
+        <h:title>Form with last-saved instance (filled)</h:title>
+        <model>
+            <instance>
+                <data>
+                    <item>Foo</item>
+                </data>
+            </instance>
+            <instance id="last-saved" src="jr://instance/last-saved"/>
+            <bind nodeset="/data/item" type="string"/>
+            <setvalue event="xforms-ready" ref="/data/item" value="instance('last-saved')/data/item"/>
+        </model>
+    </h:head>
+
+    <h:body>
+    </h:body>
+
+</h:html>

src/org/javarosa/xform/parse/XFormParser.java

@@ -349,14 +349,24 @@ public XFormParser(Document form, Document instance) {
     }
 
     public FormDef parse() throws IOException {
+        return parse(null);
+    }
+
+    /**
+     * @see #parse()
+     *
+     * @param lastSavedSrc The src of the last-saved instance of this form (for auto-filling). If null,
+     *                     no data will be loaded and the instance will be blank.
+     */
+    public FormDef parse(String lastSavedSrc) throws IOException {
         if (_f == null) {
             logger.info("Parsing form...");
 
             if (_xmldoc == null) {
                 _xmldoc = getXMLDocument(_reader, stringCache);
             }
 
-            parseDoc(buildNamespacesMap(_xmldoc.getRootElement()));
+            parseDoc(buildNamespacesMap(_xmldoc.getRootElement()), lastSavedSrc);
 
             //load in a custom xml instance, if applicable
             if (_instReader != null) {
@@ -439,7 +449,7 @@ public static Document getXMLDocument(Reader reader, CacheTable<String> stringCa
         return doc;
     }
 
-    private void parseDoc(Map<String, String> namespacePrefixesByUri) {
+    private void parseDoc(Map<String, String> namespacePrefixesByUri, String lastSavedSrc) {
         final StopWatch codeTimer = StopWatch.start();
         _f = new FormDef();
 
@@ -459,9 +469,9 @@ private void parseDoc(Map<String, String> namespacePrefixesByUri) {
             for (int instanceIndex = 1; instanceIndex < instanceNodes.size(); instanceIndex++) {
                 final Element instance = instanceNodes.get(instanceIndex);
                 final String instanceId = instanceNodeIdStrs.get(instanceIndex);
-                final String instanceSrc = instance.getAttributeValue(null, "src");
+                final String instanceSrc = parseInstanceSrc(instance, lastSavedSrc);
 
-                if (instanceSrc != null && instanceSrc.toLowerCase().startsWith("jr://file")) { // file or file-csv
+                if (instanceSrc != null) {
                     final ExternalDataInstance externalDataInstance;
                     try {
                         externalDataInstance = ExternalDataInstance.build(instanceSrc, instanceId);
@@ -513,6 +523,23 @@ This will lead to inconsistency between prefixes used in the form definition (bi
         logger.info(codeTimer.logLine("Creating FormDef from parsed XML"));
     }
 
+    private String parseInstanceSrc(Element instance, String lastSavedSrc) {
+        String rawSrc = instance.getAttributeValue(null, "src");
+        String rawSrcLower = rawSrc == null ? null : rawSrc.toLowerCase();
+
+        if (rawSrc == null) {
+            // It's internal, so src is null.
+            return null;
+        } else if (rawSrcLower.startsWith("jr://file/") || rawSrcLower.startsWith("jr://file-csv/")) {
+            return rawSrc;
+        } else if (rawSrcLower.equals("jr://instance/last-saved")) {
+            return lastSavedSrc;
+        } else {
+            logger.warn("Invalid instance `src`: " + rawSrc);
+            return null;
+        }
+    }
+
     private final Set<String> validElementNames = unmodifiableSet(new HashSet<>(asList(
         "html",
         "head",

src/org/javarosa/xform/util/XFormUtils.java

@@ -75,6 +75,16 @@ public static FormDef getFormRaw(InputStreamReader isr) throws XFormParseExcepti
      * @throws XFormParseException if the form can’t be parsed
      */
     public static FormDef getFormFromInputStream(InputStream is) throws XFormParseException {
+        return getFormFromInputStream(is, null);
+    }
+
+    /**
+     * @see #getFormFromInputStream(InputStream)
+     *
+     * @param lastSavedSrc The src of the last-saved instance of this form (for auto-filling). If null,
+     *                     no data will be loaded and the instance will be blank.
+     */
+    public static FormDef getFormFromInputStream(InputStream is, String lastSavedSrc) throws XFormParseException {
         InputStreamReader isr = null;
         try {
             try {
@@ -84,7 +94,7 @@ public static FormDef getFormFromInputStream(InputStream is) throws XFormParseEx
             }
 
             XFormParser xFormParser = _factory.getXFormParser(isr);
-            return xFormParser.parse();
+            return xFormParser.parse(lastSavedSrc);
         } catch(IOException e) {
             throw new XFormParseException("IO Exception during parse! " + e.getMessage());
         } finally {

test/org/javarosa/xform/parse/FormParserHelper.java

@@ -14,4 +14,8 @@ private FormParserHelper() {
     public static FormDef parse(Path formName) throws IOException {
         return XFormUtils.getFormFromInputStream(new FileInputStream(formName.toString()));
     }
+
+    public static FormDef parse(Path formName, String lastSavedSrc) throws IOException {
+        return XFormUtils.getFormFromInputStream(new FileInputStream(formName.toString()), lastSavedSrc);
+    }
 }

test/org/javarosa/xform/parse/XFormParserTest.java

@@ -18,6 +18,7 @@
 import org.javarosa.core.model.instance.TreeReference;
 import org.javarosa.core.model.QuestionDef;
 import org.javarosa.core.reference.ReferenceManager;
+import org.javarosa.core.reference.ReferenceManagerTestUtils;
 import org.javarosa.core.services.PrototypeManager;
 import org.javarosa.core.services.transport.payload.ByteArrayPayload;
 import org.javarosa.core.util.JavaRosaCoreModule;
@@ -126,6 +127,34 @@ public void parsesPreloadForm() throws IOException {
         assertEquals("internal select 10", formDef.getTitle());
     }
 
+    @Test public void parsesLastSavedInstanceWithNullSrc() throws IOException {
+        Path formName = r("last-saved-blank.xml");
+        FormDef formDef = parse(formName, null);
+        assertEquals("Form with last-saved instance (blank)", formDef.getTitle());
+
+        DataInstance lastSaved = formDef.getNonMainInstance("last-saved");
+        AbstractTreeElement root = lastSaved.getRoot();
+        assertEquals(0, root.getNumChildren());
+    }
+
+    @Test public void parsesLastSavedInstanceWithFilledForm() throws IOException {
+        Path formName = r("last-saved-blank.xml");
+        Path lastSavedSubmissionDirectory = r("last-saved-filled.xml").toAbsolutePath().getParent();
+        ReferenceManagerTestUtils.setUpSimpleReferenceManager("file", lastSavedSubmissionDirectory);
+        FormDef formDef = parse(formName, "jr://file/last-saved-filled.xml");
+        assertEquals("Form with last-saved instance (blank)", formDef.getTitle());
+
+        DataInstance lastSaved = formDef.getNonMainInstance("last-saved");
+        AbstractTreeElement root = lastSaved.getRoot();
+        AbstractTreeElement item = root
+            .getChild("head", 0)
+            .getChild("model", 0)
+            .getChild("instance", 0)
+            .getChild("data", 0)
+            .getChild("item", 0);
+        assertEquals("Foo", item.getValue().getDisplayText());
+    }
+
     @Test public void parsesExternalSecondaryInstanceForm() throws IOException, XPathSyntaxException {
         Path formName = EXTERNAL_SECONDARY_INSTANCE_XML;
         mapFileToResourcePath(formName);