Repository: miniflux/v2

Issue:
[Feature Request] Allow filter rules based on specific tag 
As a user, I want to be able to add a filter rule to a feed based on a specific xml tag. Currently, [filtering is only possible on the title](https://miniflux.app/docs/rules.html#filtering-rules).

## Concrete example

Considering a feed that has these entries:

```xml
<item>
    <title>My second post</title>
    <link>https://example.com/2</link>
    <description>Some content</description>
    <author>Foo Bar</author>
    <category>dev-blogs</category>
    <pubDate>Tue, 05 Jan 2021 01:50:00 GMT</pubDate>
</item>
<item>
    <title>My first post</title>
    <link>https://example.com/1</link>
    <description>Some more content</description>
    <author>Bar Baz</author>
    <category>news</category>
    <pubDate>Sun, 03 Jan 2021 11:00:00 GMT</pubDate>
</item>
```

I want to be able to only subscribe to entries marked with the category "dev-blogs".

## Possible solution

Add the possibility to specify tags in Keep/Block rules. If the rule is a tag (regex/raw character parsing?), query the entire entry. If not, continue as previously implemented, by just querying the title.

![image](https://user-images.githubusercontent.com/32395585/103639499-bb19b680-4f4e-11eb-9970-78d0e1231b8a.png)

## Resources

This feature could be implemented here:
https://github.com/miniflux/v2/blob/de7a61309878e335fe99c7afbbe6a40cc097b0ae/reader/processor/processor.go#L86

## Context

I stumbled upon this issue when I wanted to subscribe to the dev-blogs of a game. The authors only have [a single rss feed for all their content](https://www.eveonline.com/rss).

Hints from issue comments:
@garritfra: Fiddling around with this, I found that it's not as easy as I expected. In order to query non-standard attributes (like `category`), the raw entry would need to be stored. Another way would be to add an "extra tags" field, that itself is a key-value map. 

Is there a simpler way to query ever field in the original entry?@JKingweb: For what it's worth, having anticipated the usefulness of this for The Guardian's rather large news feed in my own (forthcoming) [independent implementation](https://code.mensbeam.com/MensBeam/arsse/src/commit/47ae65b9d368bfcb6585c6ce1fa828baebd05d17/lib/Rule/Rule.php#L41) of Miniflux's API, I simply had rules try to match against the title, and in the absence of a match, each category name until a match is found. So, a keep rule of `^dev-blog$` would suffice.

The downside to this is that since Miniflux doesn't actually expose RSS/Atom categories, it might be confusing for users. I'd be keen to discuss the best, least confusing way to expose such a feature.@x0tester0x: Since the parser for the <category> from Feeds  (RSS, Atom and JSON) is already merged an implemented, when and how can I use this in the block or keep rules?
@x0tester0x: Please implement this and update the Documentation.@privatmamtora: This was implemented here: #2526 
Just documentation needs to be updated@shanewstone: > This was implemented here: #2526 Just documentation needs to be updated

Please correct me if I am mistaken, but that PR only addresses global filter rules. The request here is for fields used in filter rules applied to individual feeds. The fields used to filter within specific tags (e.g., `EntryTitle`, `EntryContent`) cannot be used in a feed's keep or block rules, only in the global filter rules.@jacob-faber: @shanewstone , Yes, that's correct. Individual feed filtering needs to be refactored to use the same logic (EntryTitle, EntryContent). For my personal use, I used this patch https://github.com/miniflux/v2/compare/main...jacob-faber:miniflux-v2:filter-content to match the content of individual feeds.@epetousis: @jacob-faber would you be able to submit those changes as a PR? This would be useful for me and many others.@ubuntor: I have a patch on my personal fork to use the same syntax for global and feed filter rules: https://github.com/ubuntor/miniflux-v2/commit/18780e751822cc24d755a620458a2575d7541ccb
I haven't gotten around to upstreaming it since it's a breaking change and it needs a bit more polish.
(You can preserve the functionality of previously existing rules with a migration that converts a feed filter rule `<rule>` to `EntryTitle=<rule>\nEntryURL=<rule>\nEntryAuthor=<rule>\nEntryTag=<rule>`, but new rules would have to use the global rule syntax.)
I'm also reluctant to make it backwards-compatible since rule validation becomes much harder: if a user typos a rule as e.g. `EntryTitl=<rule>`, should it be considered as an old rule or rejected for having an invalid field name? If it's rejected, would all old rules that use `=` also be rejected?@fguillot: Your can use `EntryTag` filter in recent versions of Miniflux.

Solution patch:
diff --git a/api/entry.go b/api/entry.go
index 839f6cac..e8d6c908 100644
--- a/api/entry.go
+++ b/api/entry.go
@@ -132,6 +132,8 @@ func (h *handler) findEntries(w http.ResponseWriter, r *http.Request, feedID int
 		return
 	}
 
+	tags := request.QueryStringParamList(r, "tags")
+
 	builder := h.store.NewEntryQueryBuilder(userID)
 	builder.WithFeedID(feedID)
 	builder.WithCategoryID(categoryID)
@@ -140,6 +142,7 @@ func (h *handler) findEntries(w http.ResponseWriter, r *http.Request, feedID int
 	builder.WithDirection(direction)
 	builder.WithOffset(offset)
 	builder.WithLimit(limit)
+	builder.WithTags(tags)
 	configureFilters(builder, r)
 
 	entries, err := builder.GetEntries()
diff --git a/client/model.go b/client/model.go
index 75822167..170b6cfe 100644
--- a/client/model.go
+++ b/client/model.go
@@ -218,6 +218,7 @@ type Entry struct {
 	ReadingTime int        `json:"reading_time"`
 	Enclosures  Enclosures `json:"enclosures,omitempty"`
 	Feed        *Feed      `json:"feed,omitempty"`
+	Tags        []string   `json:"tags"`
 }
 
 // Entries represents a list of entries.
diff --git a/database/migrations.go b/database/migrations.go
index 208c7b57..433120a4 100644
--- a/database/migrations.go
+++ b/database/migrations.go
@@ -638,4 +638,10 @@ var migrations = []func(tx *sql.Tx) error{
 		_, err = tx.Exec(sql)
 		return err
 	},
+	func(tx *sql.Tx) (err error) {
+		_, err = tx.Exec(`
+			ALTER TABLE entries ADD COLUMN tags text[] default '{}';
+		`)
+		return
+	},
 }
diff --git a/model/entry.go b/model/entry.go
index ee54208a..3290d273 100644
--- a/model/entry.go
+++ b/model/entry.go
@@ -37,6 +37,7 @@ type Entry struct {
 	ReadingTime int           `json:"reading_time"`
 	Enclosures  EnclosureList `json:"enclosures"`
 	Feed        *Feed         `json:"feed,omitempty"`
+	Tags        []string      `json:"tags"`
 }
 
 // Entries represents a list of entries.
diff --git a/reader/atom/atom_10.go b/reader/atom/atom_10.go
index 6a28c064..344b0aba 100644
--- a/reader/atom/atom_10.go
+++ b/reader/atom/atom_10.go
@@ -80,14 +80,15 @@ func (a *atom10Feed) Transform(baseURL string) *model.Feed {
 }
 
 type atom10Entry struct {
-	ID        string      `xml:"id"`
-	Title     atom10Text  `xml:"title"`
-	Published string      `xml:"published"`
-	Updated   string      `xml:"updated"`
-	Links     atomLinks   `xml:"link"`
-	Summary   atom10Text  `xml:"summary"`
-	Content   atom10Text  `xml:"http://www.w3.org/2005/Atom content"`
-	Authors   atomAuthors `xml:"author"`
+	ID         string           `xml:"id"`
+	Title      atom10Text       `xml:"title"`
+	Published  string           `xml:"published"`
+	Updated    string           `xml:"updated"`
+	Links      atomLinks        `xml:"link"`
+	Summary    atom10Text       `xml:"summary"`
+	Content    atom10Text       `xml:"http://www.w3.org/2005/Atom content"`
+	Authors    atomAuthors      `xml:"author"`
+	Categories []atom10Category `xml:"category"`
 	media.Element
 }
 
@@ -101,6 +102,7 @@ func (a *atom10Entry) Transform() *model.Entry {
 	entry.Title = a.entryTitle()
 	entry.Enclosures = a.entryEnclosures()
 	entry.CommentsURL = a.entryCommentsURL()
+	entry.Tags = a.entryCategories()
 	return entry
 }
 
@@ -214,6 +216,20 @@ func (a *atom10Entry) entryEnclosures() model.EnclosureList {
 	return enclosures
 }
 
+func (r *atom10Entry) entryCategories() []string {
+	var categoryList []string
+
+	for _, atomCategory := range r.Categories {
+		if strings.TrimSpace(atomCategory.Label) != "" {
+			categoryList = append(categoryList, strings.TrimSpace(atomCategory.Label))
+		} else {
+			categoryList = append(categoryList, strings.TrimSpace(atomCategory.Term))
+		}
+	}
+
+	return categoryList
+}
+
 // See https://tools.ietf.org/html/rfc4685#section-4
 // If the type attribute of the atom:link is omitted, its value is assumed to be "application/atom+xml".
 // We accept only HTML or XHTML documents for now since the intention is to have the same behavior as RSS.
@@ -232,6 +248,11 @@ type atom10Text struct {
 	XHTMLRootElement atomXHTMLRootElement `xml:"http://www.w3.org/1999/xhtml div"`
 }
 
+type atom10Category struct {
+	Term  string `xml:"term,attr"`
+	Label string `xml:"label,attr"`
+}
+
 // Text: https://datatracker.ietf.org/doc/html/rfc4287#section-3.1.1.1
 // HTML: https://datatracker.ietf.org/doc/html/rfc4287#section-3.1.1.2
 // XHTML: https://datatracker.ietf.org/doc/html/rfc4287#section-3.1.1.3
diff --git a/reader/json/json.go b/reader/json/json.go
index 589d7cb0..759b10c7 100644
--- a/reader/json/json.go
+++ b/reader/json/json.go
@@ -43,6 +43,7 @@ type jsonItem struct {
 	Authors       []jsonAuthor     `json:"authors"`
 	Author        jsonAuthor       `json:"author"`
 	Attachments   []jsonAttachment `json:"attachments"`
+	Tags          []string         `json:"tags"`
 }
 
 type jsonAttachment struct {
@@ -181,6 +182,7 @@ func (j *jsonItem) Transform() *model.Entry {
 	entry.Content = j.GetContent()
 	entry.Title = strings.TrimSpace(j.GetTitle())
 	entry.Enclosures = j.GetEnclosures()
+	entry.Tags = j.Tags
 	return entry
 }
 
diff --git a/reader/rss/rss.go b/reader/rss/rss.go
index 76ed9c9a..2969f6bc 100644
--- a/reader/rss/rss.go
+++ b/reader/rss/rss.go
@@ -156,6 +156,12 @@ type rssEnclosure struct {
 	Length string `xml:"length,attr"`
 }
 
+type rssCategory struct {
+	XMLName xml.Name
+	Data    string `xml:",chardata"`
+	Inner   string `xml:",innerxml"`
+}
+
 func (enclosure *rssEnclosure) Size() int64 {
 	if enclosure.Length == "" {
 		return 0
@@ -173,6 +179,7 @@ type rssItem struct {
 	Authors        []rssAuthor      `xml:"author"`
 	CommentLinks   []rssCommentLink `xml:"comments"`
 	EnclosureLinks []rssEnclosure   `xml:"enclosure"`
+	Categories     []rssCategory    `xml:"category"`
 	DublinCoreElement
 	FeedBurnerElement
 	PodcastEntryElement
@@ -189,6 +196,8 @@ func (r *rssItem) Transform() *model.Entry {
 	entry.Content = r.entryContent()
 	entry.Title = r.entryTitle()
 	entry.Enclosures = r.entryEnclosures()
+	entry.Tags = r.entryCategories()
+
 	return entry
 }
 
@@ -372,6 +381,20 @@ func (r *rssItem) entryEnclosures() model.EnclosureList {
 	return enclosures
 }
 
+func (r *rssItem) entryCategories() []string {
+	var categoryList []string
+
+	for _, rssCategory := range r.Categories {
+		if strings.Contains(rssCategory.Inner, "<![CDATA[") {
+			categoryList = append(categoryList, strings.TrimSpace(rssCategory.Data))
+		} else {
+			categoryList = append(categoryList, strings.TrimSpace(rssCategory.Inner))
+		}
+	}
+
+	return categoryList
+}
+
 func (r *rssItem) entryCommentsURL() string {
 	for _, commentLink := range r.CommentLinks {
 		if commentLink.XMLName.Space == "" {
diff --git a/storage/entry.go b/storage/entry.go
index 5f062f7f..f99d9ccc 100644
--- a/storage/entry.go
+++ b/storage/entry.go
@@ -119,7 +119,8 @@ func (s *Storage) createEntry(tx *sql.Tx, entry *model.Entry) error {
 				feed_id,
 				reading_time,
 				changed_at,
-				document_vectors
+				document_vectors,
+				tags
 			)
 		VALUES
 			(
@@ -134,7 +135,8 @@ func (s *Storage) createEntry(tx *sql.Tx, entry *model.Entry) error {
 				$9,
 				$10,
 				now(),
-				setweight(to_tsvector(left(coalesce($1, ''), 500000)), 'A') || setweight(to_tsvector(left(coalesce($6, ''), 500000)), 'B')
+				setweight(to_tsvector(left(coalesce($1, ''), 500000)), 'A') || setweight(to_tsvector(left(coalesce($6, ''), 500000)), 'B'),
+				$11
 			)
 		RETURNING
 			id, status
@@ -151,6 +153,7 @@ func (s *Storage) createEntry(tx *sql.Tx, entry *model.Entry) error {
 		entry.UserID,
 		entry.FeedID,
 		entry.ReadingTime,
+		pq.Array(removeDuplicates(entry.Tags)),
 	).Scan(&entry.ID, &entry.Status)
 
 	if err != nil {
@@ -183,7 +186,8 @@ func (s *Storage) updateEntry(tx *sql.Tx, entry *model.Entry) error {
 			content=$4,
 			author=$5,
 			reading_time=$6,
-			document_vectors = setweight(to_tsvector(left(coalesce($1, ''), 500000)), 'A') || setweight(to_tsvector(left(coalesce($4, ''), 500000)), 'B')
+			document_vectors = setweight(to_tsvector(left(coalesce($1, ''), 500000)), 'A') || setweight(to_tsvector(left(coalesce($4, ''), 500000)), 'B'),
+			tags=$10
 		WHERE
 			user_id=$7 AND feed_id=$8 AND hash=$9
 		RETURNING
@@ -200,6 +204,7 @@ func (s *Storage) updateEntry(tx *sql.Tx, entry *model.Entry) error {
 		entry.UserID,
 		entry.FeedID,
 		entry.Hash,
+		pq.Array(removeDuplicates(entry.Tags)),
 	).Scan(&entry.ID)
 
 	if err != nil {
@@ -535,3 +540,16 @@ func (s *Storage) UnshareEntry(userID int64, entryID int64) (err error) {
 	}
 	return
 }
+
+// removeDuplicate removes duplicate entries from a slice
+func removeDuplicates[T string | int](sliceList []T) []T {
+	allKeys := make(map[T]bool)
+	list := []T{}
+	for _, item := range sliceList {
+		if _, value := allKeys[item]; !value {
+			allKeys[item] = true
+			list = append(list, item)
+		}
+	}
+	return list
+}
diff --git a/storage/entry_query_builder.go b/storage/entry_query_builder.go
index 437e769c..dae7bc1f 100644
--- a/storage/entry_query_builder.go
+++ b/storage/entry_query_builder.go
@@ -135,6 +135,17 @@ func (e *EntryQueryBuilder) WithStatuses(statuses []string) *EntryQueryBuilder {
 	return e
 }
 
+// WithTags filter by a list of entry tags.
+func (e *EntryQueryBuilder) WithTags(tags []string) *EntryQueryBuilder {
+	if len(tags) > 0 {
+		for _, cat := range tags {
+			e.conditions = append(e.conditions, fmt.Sprintf("$%d = ANY(e.tags)", len(e.args)+1))
+			e.args = append(e.args, cat)
+		}
+	}
+	return e
+}
+
 // WithoutStatus set the entry status that should not be returned.
 func (e *EntryQueryBuilder) WithoutStatus(status string) *EntryQueryBuilder {
 	if status != "" {
@@ -250,6 +261,7 @@ func (e *EntryQueryBuilder) GetEntries() (model.Entries, error) {
 			e.reading_time,
 			e.created_at,
 			e.changed_at,
+			e.tags,
 			f.title as feed_title,
 			f.feed_url,
 			f.site_url,
@@ -312,6 +324,7 @@ func (e *EntryQueryBuilder) GetEntries() (model.Entries, error) {
 			&entry.ReadingTime,
 			&entry.CreatedAt,
 			&entry.ChangedAt,
+			pq.Array(&entry.Tags),
 			&entry.Feed.Title,
 			&entry.Feed.FeedURL,
 			&entry.Feed.SiteURL,



Test patch:
diff --git a/reader/atom/atom_10_test.go b/reader/atom/atom_10_test.go
index c6a50ef0..bf45a7a9 100644
--- a/reader/atom/atom_10_test.go
+++ b/reader/atom/atom_10_test.go
@@ -1604,3 +1604,48 @@ func TestAbsoluteCommentsURL(t *testing.T) {
 		t.Errorf("Incorrect entry comments URL, got: %s", feed.Entries[0].CommentsURL)
 	}
 }
+
+func TestParseFeedWithCategories(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+	<feed xmlns="http://www.w3.org/2005/Atom">
+	  <title>Example Feed</title>
+	  <link href="http://example.org/"/>
+	  <author>
+		<name>Alice</name>
+	  </author>
+	  <author>
+		<name>Bob</name>
+	  </author>
+
+	  <entry>
+		<link href="http://example.org/2003/12/13/atom03"/>
+		<id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
+		<updated>2003-12-13T18:30:02Z</updated>
+		<summary>Some text.</summary>
+		<category term='Tech' />
+		<category term='Technology' label='Science' />
+	  </entry>
+
+	</feed>`
+
+	feed, err := Parse("https://example.org/", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(feed.Entries[0].Tags) != 2 {
+		t.Errorf("Incorrect number of tags, got: %d", len(feed.Entries[0].Tags))
+	}
+
+	expected := "Tech"
+	result := feed.Entries[0].Tags[0]
+	if result != expected {
+		t.Errorf("Incorrect entry category, got %q instead of %q", result, expected)
+	}
+
+	expected = "Science"
+	result = feed.Entries[0].Tags[1]
+	if result != expected {
+		t.Errorf("Incorrect entry category, got %q instead of %q", result, expected)
+	}
+}
diff --git a/reader/json/parser_test.go b/reader/json/parser_test.go
index 5ba82d45..186baca6 100644
--- a/reader/json/parser_test.go
+++ b/reader/json/parser_test.go
@@ -575,3 +575,45 @@ func TestParseInvalidJSON(t *testing.T) {
 		t.Error("Parse should returns an error")
 	}
 }
+
+func TestParseTags(t *testing.T) {
+	data := `{
+		"version": "https://jsonfeed.org/version/1",
+		"user_comment": "This is a microblog feed. You can add this to your feed reader using the following URL: https://example.org/feed.json",
+		"title": "Brent Simmons’s Microblog",
+		"home_page_url": "https://example.org/",
+		"feed_url": "https://example.org/feed.json",
+		"author": {
+			"name": "Brent Simmons",
+			"url": "http://example.org/",
+			"avatar": "https://example.org/avatar.png"
+		},
+		"items": [
+			{
+				"id": "2347259",
+				"url": "https://example.org/2347259",
+				"content_text": "Cats are neat. \n\nhttps://example.org/cats",
+				"date_published": "2016-02-09T14:22:00-07:00",
+				"tags": [
+					"tag 1",
+					"tag 2"
+				]
+			}
+		]
+	}`
+
+	feed, err := Parse("https://example.org/feed.json", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(feed.Entries[0].Tags) != 2 {
+		t.Errorf("Incorrect number of Tags, got: %d", len(feed.Entries[0].Tags))
+	}
+
+	expected := "tag 2"
+	result := feed.Entries[0].Tags[1]
+	if result != expected {
+		t.Errorf("Incorrect entry tag, got %q instead of %q", result, expected)
+	}
+}
diff --git a/reader/rss/parser_test.go b/reader/rss/parser_test.go
index 4b7bf761..d0662c60 100644
--- a/reader/rss/parser_test.go
+++ b/reader/rss/parser_test.go
@@ -1426,3 +1426,69 @@ func TestEntryDescriptionFromGooglePlayDescription(t *testing.T) {
 		t.Errorf(`Unexpected podcast content, got %q instead of %q`, result, expected)
 	}
 }
+
+func TestParseEntryWithCategoryAndInnerHTML(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+		<rss xmlns:atom="http://www.w3.org/2005/Atom" version="2.0">
+		<channel>
+			<title>Example</title>
+			<link>https://example.org/</link>
+			<atom:link href="https://example.org/rss" type="application/rss+xml" rel="self"></atom:link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+				<category>Category 1</category>
+				<category>Category 2</category>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(feed.Entries[0].Tags) != 2 {
+		t.Errorf("Incorrect number of tags, got: %d", len(feed.Entries[0].Tags))
+	}
+
+	expected := "Category 2"
+	result := feed.Entries[0].Tags[1]
+	if result != expected {
+		t.Errorf("Incorrect entry category, got %q instead of %q", result, expected)
+	}
+}
+
+func TestParseEntryWithCategoryAndCDATA(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+		<rss xmlns:atom="http://www.w3.org/2005/Atom" version="2.0">
+		<channel>
+			<title>Example</title>
+			<link>https://example.org/</link>
+			<atom:link href="https://example.org/rss" type="application/rss+xml" rel="self"></atom:link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+				<author>
+					by <![CDATA[Foo Bar]]>
+				</author>
+				<category>Sample Category</category>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(feed.Entries[0].Tags) != 1 {
+		t.Errorf("Incorrect number of tags, got: %d", len(feed.Entries[0].Tags))
+	}
+
+	expected := "Sample Category"
+	result := feed.Entries[0].Tags[0]
+	if result != expected {
+		t.Errorf("Incorrect entry category, got %q instead of %q", result, expected)
+	}
+}