Added <dc:issued> field to OPDS entries

src/opds_dumper.cpp

@@ -72,6 +72,7 @@ IllustrationInfo getBookIllustrationInfo(const Book& book)
 
 kainjow::mustache::object getSingleBookData(const Book& book)
 {
+    const auto bookDate = book.getDate() + "T00:00:00Z";
     const MustacheData bookUrl = book.getUrl().empty()
                                ? MustacheData(false)
                                : MustacheData(book.getUrl());
@@ -82,7 +83,8 @@ kainjow::mustache::object getSingleBookData(const Book& book)
       {"description", book.getDescription()},
       {"language", book.getLanguage()},
       {"content_id",  urlEncode(book.getHumanReadableIdFromPath(), true)},
-      {"updated", book.getDate() + "T00:00:00Z"},
+      {"updated", bookDate}, // XXX: this should be the entry update datetime
+      {"book_date", bookDate},
       {"category", book.getCategory()},
       {"flavour", book.getFlavour()},
       {"tags", book.getTags()},

static/templates/catalog_entries.xml

@@ -1,4 +1,6 @@
-<feed xmlns="http://www.w3.org/2005/Atom" xmlns:opds="http://opds-spec.org/2010/catalog">
+<feed xmlns="http://www.w3.org/2005/Atom"
+      xmlns:dc="http://purl.org/dc/terms/"
+      xmlns:opds="http://opds-spec.org/2010/catalog">
   <id>{{feed_id}}</id>
   <title>{{^filter}}All zims{{/filter}}{{#filter}}Filtered zims ({{filter}}){{/filter}}</title>
   <updated>{{date}}</updated>

static/templates/catalog_v2_entries.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <feed xmlns="http://www.w3.org/2005/Atom"
+      xmlns:dc="http://purl.org/dc/terms/"
       xmlns:opds="https://specs.opds.io/opds-1.2"
       xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/">
   <id>{{feed_id}}</id>

static/templates/catalog_v2_entry.xml

@@ -25,6 +25,7 @@
     <publisher>
       <name>{{publisher_name}}</name>
     </publisher>
+    <dc:issued>{{book_date}}</dc:issued>
     {{#url}}
     <link rel="http://opds-spec.org/acquisition/open-access" type="application/x-zim" href="{{{url}}}" length="{{{size}}}" />
     {{/url}}

test/server.cpp

@@ -1081,7 +1081,8 @@ std::string maskVariableOPDSFeedData(std::string s)
 }
 
 #define OPDS_FEED_TAG \
-    "<feed xmlns=\"http://www.w3.org/2005/Atom\"" \
+    "<feed xmlns=\"http://www.w3.org/2005/Atom\"\n" \
+    "      xmlns:dc=\"http://purl.org/dc/terms/\"\n" \
     "      xmlns:opds=\"http://opds-spec.org/2010/catalog\">\n"
 
 #define CATALOG_LINK_TAGS \
@@ -1110,6 +1111,7 @@ std::string maskVariableOPDSFeedData(std::string s)
     "    <publisher>\n"                                                 \
     "      <name>Kiwix</name>\n"                                        \
     "    </publisher>\n"                                                \
+    "    <dc:issued>2020-03-31T00:00:00Z</dc:issued>\n"                 \
     "    <link rel=\"http://opds-spec.org/acquisition/open-access\" type=\"application/x-zim\" href=\"https://github.com/kiwix/libkiwix/raw/master/test/data/zimfile%26other.zim\" length=\"569344\" />\n" \
     "  </entry>\n"
 
@@ -1136,6 +1138,7 @@ std::string maskVariableOPDSFeedData(std::string s)
     "    <publisher>\n"                                                 \
     "      <name>Kiwix</name>\n"                                        \
     "    </publisher>\n"                                                \
+    "    <dc:issued>2020-03-31T00:00:00Z</dc:issued>\n"                 \
     "    <link rel=\"http://opds-spec.org/acquisition/open-access\" type=\"application/x-zim\" href=\"https://github.com/kiwix/libkiwix/raw/master/test/data/zimfile.zim\" length=\"569344\" />\n" \
     "  </entry>\n"
 
@@ -1159,6 +1162,7 @@ std::string maskVariableOPDSFeedData(std::string s)
     "    <publisher>\n"                                                 \
     "      <name>Kiwix</name>\n"                                        \
     "    </publisher>\n"                                                \
+    "    <dc:issued>2020-03-31T00:00:00Z</dc:issued>\n"                 \
     "    <link rel=\"http://opds-spec.org/acquisition/open-access\" type=\"application/x-zim\" href=\"https://github.com/kiwix/libkiwix/raw/master/test/data/zimfile.zim\" length=\"125952\" />\n" \
     "  </entry>\n"
 
@@ -1574,6 +1578,7 @@ TEST_F(LibraryServerTest, catalog_v2_languages)
 #define CATALOG_V2_ENTRIES_PREAMBLE0(x)                       \
     "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"            \
     "<feed xmlns=\"http://www.w3.org/2005/Atom\"\n"           \
+    "      xmlns:dc=\"http://purl.org/dc/terms/\"\n"          \
     "      xmlns:opds=\"https://specs.opds.io/opds-1.2\"\n"   \
     "      xmlns:opensearch=\"http://a9.com/-/spec/opensearch/1.1/\">\n"  \
     "  <id>12345678-90ab-cdef-1234-567890abcdef</id>\n"       \