html-meta-scraper 0.3.0

Scrape and extract metadata like title, description, images, and favicon from HTML documents.
Documentation 
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//! Extract metadata from an HTML document — `<title>`, OpenGraph and
//! Twitter Card tags, favicon, and the root `<html lang>` attribute.
//!
//! This crate parses HTML strings you provide; it does not fetch URLs.
//!
//! # Example
//!
//! ```
//! use html_meta_scraper::MetaScraper;
//!
//! let html = r#"
//!     <html lang="en">
//!         <head>
//!             <title>Native Title</title>
//!             <meta property="og:title" content="OG Title" />
//!             <meta property="og:image" content="https://example.com/cover.jpg" />
//!         </head>
//!     </html>
//! "#;
//!
//! let m = MetaScraper::new(html);
//! assert_eq!(m.title().as_deref(), Some("OG Title"));
//! assert_eq!(m.image().as_deref(), Some("https://example.com/cover.jpg"));
//! assert_eq!(m.lang().as_deref(), Some("en"));
//! ```

/// Holds a parsed HTML document and exposes accessors for common page
/// metadata.
///
/// Construct one with [`MetaScraper::new`], then call the per-field
/// accessors. The document is parsed once at construction time; accessors
/// are read-only and may be called repeatedly.
pub struct MetaScraper {
    document: scraper::Html,
}

impl MetaScraper {
    /// Parse an HTML document.
    ///
    /// Parsing is eager and lenient — malformed HTML will not panic.
    pub fn new(html: &str) -> Self {
        let document = scraper::Html::parse_document(html);

        MetaScraper { document }
    }

    /// Returns the trimmed text of the first `<title>` element.
    ///
    /// Returns `None` if the tag is absent, empty, or whitespace-only.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new("<title>Page Title</title>");
    /// assert_eq!(m.extract_title().as_deref(), Some("Page Title"));
    /// ```
    pub fn extract_title(&self) -> Option<String> {
        self.document
            .select(&scraper::Selector::parse("title").unwrap())
            .next()
            .map(|element| element.text().collect::<String>().trim().to_string())
            .filter(|s| !s.is_empty())
    }

    /// Returns the OpenGraph title from `<meta property="og:title">`.
    ///
    /// Also accepts the non-conformant `<meta name="og:title">` variant
    /// emitted by some CMSes. An empty `content` attribute is treated as
    /// absent.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta property="og:title" content="Hello" />"#);
    /// assert_eq!(m.extract_og_title().as_deref(), Some("Hello"));
    /// ```
    pub fn extract_og_title(&self) -> Option<String> {
        let og_title_selector =
            scraper::Selector::parse("meta[property='og:title'], meta[name='og:title']").unwrap();

        let og_title = self
            .document
            .select(&og_title_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        og_title
    }

    /// Returns the Twitter Card title from `<meta name="twitter:title">`.
    ///
    /// Also accepts `<meta property="twitter:title">`, which appears in
    /// the wild. An empty `content` attribute is treated as absent.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta name="twitter:title" content="Hello" />"#);
    /// assert_eq!(m.extract_twitter_title().as_deref(), Some("Hello"));
    /// ```
    pub fn extract_twitter_title(&self) -> Option<String> {
        let twitter_title_selector =
            scraper::Selector::parse("meta[name='twitter:title'], meta[property='twitter:title']")
                .unwrap();

        let twitter_title = self
            .document
            .select(&twitter_title_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        twitter_title
    }

    /// Returns the page title, trying each source in turn and returning
    /// the first match:
    ///
    /// 1. [`extract_og_title`](Self::extract_og_title) — `og:title`
    /// 2. [`extract_twitter_title`](Self::extract_twitter_title) — `twitter:title`
    /// 3. [`extract_title`](Self::extract_title) — `<title>`
    pub fn title(&self) -> Option<String> {
        self.extract_og_title()
            .or_else(|| self.extract_twitter_title())
            .or_else(|| self.extract_title())
    }

    /// Returns the standard description from `<meta name="description">`.
    ///
    /// An empty `content` attribute is treated as absent.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta name="description" content="A page." />"#);
    /// assert_eq!(m.extract_description().as_deref(), Some("A page."));
    /// ```
    pub fn extract_description(&self) -> Option<String> {
        let description_selector = scraper::Selector::parse("meta[name='description']").unwrap();

        let description = self
            .document
            .select(&description_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        description
    }

    /// Returns the OpenGraph description from
    /// `<meta property="og:description">`.
    ///
    /// Also accepts the non-conformant `<meta name="og:description">`
    /// variant. An empty `content` attribute is treated as absent.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta property="og:description" content="A page." />"#);
    /// assert_eq!(m.extract_og_description().as_deref(), Some("A page."));
    /// ```
    pub fn extract_og_description(&self) -> Option<String> {
        let og_description_selector = scraper::Selector::parse(
            "meta[property='og:description'], meta[name='og:description']",
        )
        .unwrap();

        let og_description = self
            .document
            .select(&og_description_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        og_description
    }

    /// Returns the Twitter Card description from
    /// `<meta name="twitter:description">`.
    ///
    /// Also accepts `<meta property="twitter:description">`. An empty
    /// `content` attribute is treated as absent.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta name="twitter:description" content="A page." />"#);
    /// assert_eq!(m.extract_twitter_description().as_deref(), Some("A page."));
    /// ```
    pub fn extract_twitter_description(&self) -> Option<String> {
        let twitter_description_selector = scraper::Selector::parse(
            "meta[name='twitter:description'], meta[property='twitter:description']",
        )
        .unwrap();

        let twitter_description = self
            .document
            .select(&twitter_description_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        twitter_description
    }

    /// Returns the page description, trying each source in turn and
    /// returning the first match:
    ///
    /// 1. [`extract_og_description`](Self::extract_og_description) — `og:description`
    /// 2. [`extract_twitter_description`](Self::extract_twitter_description) — `twitter:description`
    /// 3. [`extract_description`](Self::extract_description) — `<meta name="description">`
    pub fn description(&self) -> Option<String> {
        self.extract_og_description()
            .or_else(|| self.extract_twitter_description())
            .or_else(|| self.extract_description())
    }

    /// Returns the `href` of the first `<link>` whose `rel` contains
    /// `icon` as a whitespace-separated token.
    ///
    /// Matches `rel="icon"`, `rel="shortcut icon"`, `rel="icon shortcut"`,
    /// and similar forms. Does not match `apple-touch-icon` (that's a
    /// single different token).
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<link rel="shortcut icon" href="/favicon.ico" />"#);
    /// assert_eq!(m.favicon().as_deref(), Some("/favicon.ico"));
    /// ```
    pub fn favicon(&self) -> Option<String> {
        let favicon_selector = scraper::Selector::parse("link[rel~='icon']").unwrap();

        let favicon = self
            .document
            .select(&favicon_selector)
            .next()
            .and_then(|element| element.value().attr("href").map(|href| href.to_string()));

        favicon
    }

    /// Returns the first OpenGraph image URL from
    /// `<meta property="og:image">`.
    ///
    /// Also accepts the non-conformant `<meta name="og:image">` variant.
    /// An empty `content` attribute is treated as absent. For pages that
    /// declare multiple images, see [`extract_og_images`](Self::extract_og_images).
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta property="og:image" content="https://example.com/i.jpg" />"#);
    /// assert_eq!(m.extract_og_image().as_deref(), Some("https://example.com/i.jpg"));
    /// ```
    pub fn extract_og_image(&self) -> Option<String> {
        let og_image_selector =
            scraper::Selector::parse("meta[property='og:image'], meta[name='og:image']").unwrap();

        let og_image = self
            .document
            .select(&og_image_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        og_image
    }

    /// Returns every OpenGraph image URL in document order.
    ///
    /// Both `<meta property="og:image">` and `<meta name="og:image">`
    /// contribute. Empty `content` attributes are skipped. Returns an
    /// empty `Vec` if none are declared.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"
    ///     <meta property="og:image" content="https://example.com/a.jpg" />
    ///     <meta property="og:image" content="https://example.com/b.png" />
    /// "#);
    /// assert_eq!(
    ///     m.extract_og_images(),
    ///     vec!["https://example.com/a.jpg", "https://example.com/b.png"],
    /// );
    /// ```
    pub fn extract_og_images(&self) -> Vec<String> {
        let og_image_selector =
            scraper::Selector::parse("meta[property='og:image'], meta[name='og:image']").unwrap();

        let og_images = self
            .document
            .select(&og_image_selector)
            .filter_map(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string())
            .collect::<Vec<String>>();

        og_images
    }

    /// Returns the Twitter Card image URL from
    /// `<meta name="twitter:image">`.
    ///
    /// Also accepts `<meta property="twitter:image">`. An empty `content`
    /// attribute is treated as absent. Related tags such as
    /// `twitter:image:alt` are not returned.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<meta name="twitter:image" content="https://example.com/i.jpg" />"#);
    /// assert_eq!(m.extract_twitter_image().as_deref(), Some("https://example.com/i.jpg"));
    /// ```
    pub fn extract_twitter_image(&self) -> Option<String> {
        let twitter_image_selector =
            scraper::Selector::parse("meta[name='twitter:image'], meta[property='twitter:image']")
                .unwrap();

        let twitter_image = self
            .document
            .select(&twitter_image_selector)
            .next()
            .and_then(|element| element.value().attr("content"))
            .filter(|content| !content.is_empty())
            .map(|content| content.to_string());

        twitter_image
    }

    /// Returns the page image URL, trying each source in turn and
    /// returning the first match:
    ///
    /// 1. [`extract_og_image`](Self::extract_og_image) — `og:image`
    /// 2. [`extract_twitter_image`](Self::extract_twitter_image) — `twitter:image`
    ///
    /// There is no native HTML element to fall back to, so an absent
    /// result simply means neither tag was declared.
    pub fn image(&self) -> Option<String> {
        self.extract_og_image()
            .or_else(|| self.extract_twitter_image())
    }

    /// Returns the value of the root `<html lang="...">` attribute.
    ///
    /// # Example
    ///
    /// ```
    /// # use html_meta_scraper::MetaScraper;
    /// let m = MetaScraper::new(r#"<html lang="en"><head></head></html>"#);
    /// assert_eq!(m.lang().as_deref(), Some("en"));
    /// ```
    pub fn lang(&self) -> Option<String> {
        let html_selector = scraper::Selector::parse("html").unwrap();

        let lang = self
            .document
            .select(&html_selector)
            .next()
            .and_then(|element| {
                element
                    .value()
                    .attr("lang")
                    .map(|content| content.to_string())
            });

        lang
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn extract_title() {
        let scraper = MetaScraper::new(r#"<title>Page Title</title>"#);

        let title = scraper.extract_title();

        assert_eq!(title, Some("Page Title".to_string()));
    }

    #[test]
    fn extract_og_title() {
        let scraper = MetaScraper::new(r#"<meta property="og:title" content="Page Title" />"#);

        let og_title = scraper.extract_og_title();

        assert_eq!(og_title, Some("Page Title".to_string()));
    }

    #[test]
    fn extract_twitter_title() {
        let scraper = MetaScraper::new(r#"<meta name="twitter:title" content="Page Title" />"#);

        let og_title = scraper.extract_twitter_title();

        assert_eq!(og_title, Some("Page Title".to_string()));
    }

    #[test]
    fn extract_description() {
        let scraper = MetaScraper::new(r#"<meta name="description" content="My Description" />"#);

        let description = scraper.extract_description();

        assert_eq!(description, Some("My Description".to_string()));
    }

    #[test]
    fn extract_og_description() {
        let scraper =
            MetaScraper::new(r#"<meta property="og:description" content="My Description" />"#);

        let og_description = scraper.extract_og_description();

        assert_eq!(og_description, Some("My Description".to_string()));
    }

    #[test]
    fn extract_twitter_description() {
        let scraper =
            MetaScraper::new(r#"<meta name="twitter:description" content="My Description" />"#);

        let twitter_description = scraper.extract_twitter_description();

        assert_eq!(twitter_description, Some("My Description".to_string()));
    }

    #[test]
    fn favicon() {
        let scraper = MetaScraper::new(r#"<link rel="icon" href="/favicon.ico" />"#);

        let favicon = scraper.favicon();

        assert_eq!(favicon, Some("/favicon.ico".to_string()));
    }

    #[test]
    fn extract_og_image() {
        let scraper = MetaScraper::new(
            r#"<meta property="og:image" content="https://example.com/image.jpg" />"#,
        );

        let og_image = scraper.extract_og_image();

        assert_eq!(og_image, Some("https://example.com/image.jpg".to_string()));
    }

    #[test]
    fn extract_og_images() {
        let scraper = MetaScraper::new(
            r#"
            <meta property="og:image" content="https://example.com/image.jpg" />
            <meta property="og:image" content="https://example.com/image.png" />"#,
        );

        let og_image = scraper.extract_og_images();

        assert_eq!(
            og_image,
            vec![
                "https://example.com/image.jpg".to_string(),
                "https://example.com/image.png".to_string()
            ]
        );
    }

    #[test]
    fn extract_twitter_image() {
        let scraper = MetaScraper::new(
            r#"<meta name="twitter:image" content="https://example.com/image.jpg" />"#,
        );

        let twitter_image = scraper.extract_twitter_image();

        assert_eq!(
            twitter_image,
            Some("https://example.com/image.jpg".to_string())
        );
    }

    #[test]
    fn lang() {
        let scraper = MetaScraper::new(
            r#"
            <html lang="en">
            ...
            </html>
        "#,
        );

        let lang = scraper.lang();

        assert_eq!(lang, Some("en".to_owned()));
    }

    // ---------------------------------------------------------------------
    // Bug-reproduction tests. These encode the desired behavior and are
    // expected to FAIL against the current implementation.
    // ---------------------------------------------------------------------

    #[test]
    fn empty_title_tag_returns_none() {
        let scraper = MetaScraper::new(r#"<title></title>"#);
        assert_eq!(scraper.extract_title(), None);
    }

    #[test]
    fn title_whitespace_is_trimmed() {
        let scraper = MetaScraper::new("<title>\n  Page Title\n</title>");
        assert_eq!(scraper.extract_title(), Some("Page Title".to_string()));
    }

    #[test]
    fn empty_og_title_content_returns_none() {
        let scraper = MetaScraper::new(r#"<meta property="og:title" content="" />"#);
        assert_eq!(scraper.extract_og_title(), None);
    }

    #[test]
    fn empty_description_content_returns_none() {
        let scraper = MetaScraper::new(r#"<meta name="description" content="" />"#);
        assert_eq!(scraper.extract_description(), None);
    }

    #[test]
    fn og_title_with_name_attribute_is_recognized() {
        // Some CMSes emit `name="og:..."` instead of `property="og:..."`.
        let scraper = MetaScraper::new(r#"<meta name="og:title" content="Page Title" />"#);
        assert_eq!(scraper.extract_og_title(), Some("Page Title".to_string()));
    }

    #[test]
    fn og_description_with_name_attribute_is_recognized() {
        let scraper =
            MetaScraper::new(r#"<meta name="og:description" content="My Description" />"#);
        assert_eq!(
            scraper.extract_og_description(),
            Some("My Description".to_string())
        );
    }

    #[test]
    fn og_image_with_name_attribute_is_recognized() {
        let scraper =
            MetaScraper::new(r#"<meta name="og:image" content="https://example.com/i.jpg" />"#);
        assert_eq!(
            scraper.extract_og_image(),
            Some("https://example.com/i.jpg".to_string())
        );
    }

    #[test]
    fn twitter_title_with_property_attribute_is_recognized() {
        // Mirror case: Twitter tags sometimes appear as `property=`.
        let scraper = MetaScraper::new(r#"<meta property="twitter:title" content="Page Title" />"#);
        assert_eq!(
            scraper.extract_twitter_title(),
            Some("Page Title".to_string())
        );
    }

    #[test]
    fn twitter_description_with_property_attribute_is_recognized() {
        let scraper =
            MetaScraper::new(r#"<meta property="twitter:description" content="My Description" />"#);
        assert_eq!(
            scraper.extract_twitter_description(),
            Some("My Description".to_string())
        );
    }

    #[test]
    fn twitter_image_with_property_attribute_is_recognized() {
        let scraper = MetaScraper::new(
            r#"<meta property="twitter:image" content="https://example.com/i.jpg" />"#,
        );
        assert_eq!(
            scraper.extract_twitter_image(),
            Some("https://example.com/i.jpg".to_string())
        );
    }

    #[test]
    fn favicon_matches_shortcut_icon() {
        let scraper = MetaScraper::new(r#"<link rel="shortcut icon" href="/favicon.ico" />"#);
        assert_eq!(scraper.favicon(), Some("/favicon.ico".to_string()));
    }

    #[test]
    fn favicon_matches_multi_token_rel() {
        let scraper = MetaScraper::new(r#"<link rel="icon shortcut" href="/favicon.ico" />"#);
        assert_eq!(scraper.favicon(), Some("/favicon.ico".to_string()));
    }

    #[test]
    fn title_fallback_prefers_og_over_twitter_over_native() {
        let scraper = MetaScraper::new(
            r#"
            <title>Native Title</title>
            <meta property="og:title" content="OG Title" />
            <meta name="twitter:title" content="Twitter Title" />
            "#,
        );
        assert_eq!(scraper.title(), Some("OG Title".to_string()));

        let scraper = MetaScraper::new(
            r#"
            <title>Native Title</title>
            <meta name="twitter:title" content="Twitter Title" />
            "#,
        );
        assert_eq!(scraper.title(), Some("Twitter Title".to_string()));

        let scraper = MetaScraper::new(r#"<title>Native Title</title>"#);
        assert_eq!(scraper.title(), Some("Native Title".to_string()));
    }

    #[test]
    fn title_returns_none_when_no_source_present() {
        let scraper = MetaScraper::new(r#"<html><head></head><body></body></html>"#);
        assert_eq!(scraper.title(), None);
    }
}