Answers.Body: <p>Yes, you can accomplish that using SubGroups in Calibre. The way to do a subgroup is described here (for user entered Genres) but I'll do the TL;DR below for how to do it with publication dates: <a href="https://manual.calibre-ebook.com/sub_groups.html" rel="nofollow noreferrer">https://manual.calibre-ebook.com/sub_groups.html</a></p>
  
  <ol>
  <li><p>Create a custom column with desired lookup name (yearpub) and heading and give the column type "Column built from other columns, behaves like tags"</p></li>
  <li><p>In the Template box, enter this code: <code>{pubdate:'test($,
  strcat(substr(format_date($,'yyyy'), 0, 3), '0.',format_date($,'yyyy')),
  'Unknown')'}</code></p></li>
  <li><p>Set "Sort/search columb by" to TEXT and mark a check in the "Show in tags browser".</p></li>
  <li><p>After restarting Calibre, go to Preferences-->Look and Feel-->Tag Browser and in the entry "Categories with hierarchical items" enter your custom column's lookup name.</p></li>
  </ol>
  
  <p>Now, what that all does is takes the Published Date data of that book/entry and puts it in the format of an hierarchical tag by decade.year which will now show in the Tags Browser under the lookup name you gave, then the decade, then the year. All without having to enter in any extra data! Just make sure the published date is correct. If no published date is given it will mark it as Unknown.</p>
  
  <p>Enjoy!</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-04-03T05:11:03.167Z
Answers.LastActivityDate: 2017-04-03T05:11:03.167Z
Answers.UserDisplayName: GaetaWoo
Answers.Body: <p>It seems that this is not directly possible, but you can add an additional column to achieve something like this:</p>
  
  <ol>
  <li>Go to <kbd>Preferences → Add your own columns</kbd></li>
  <li><p><kbd>Add custom column</kbd>:</p>
  
  <ol>
  <li>Give it a name and a heading (this will be displayed in the tag browser)</li>
  <li>Select <kbd>Column built from other columns</kbd></li>
  <li><p>Under "Template", enter the name of the date-based column you want to display, e.g.: </p>
  
  <pre><code>{#originalpublicationyear}
  </code></pre></li>
  <li>Enable <kbd>Show in tags browser</kbd></li>
  <li><kbd>OK</kbd></li>
  </ol></li>
  <li><kbd>Apply</kbd> and restart Calibre</li>
  </ol>
  
  <p>Now this new column should be displayed as category in the tag browser. </p>
  
  <p>Note that you can hide it as column in the book list, it will still work in the tag browser.</p>
  
  <h3>Grouping (sub-categorization)</h3>
  
  <p>Unfortunately, the grouping is not really helpful, because it uses only the year’s first character like "1" and "2" (in case of "By first letter"), or a range like "1985 - 1997" and "1997 - 2014" (in case of "Partition"). </p>
  
  <p>In the first case, filtering by group doesn’t seem to work correctly, and in the second case filtering isn’t possible by design.</p>
  
  <p>So you might want to exclude this category from partitioning (under: <kbd>Preferences → Look and Feel → Tag Browser</kbd>), in which case you get a simple list:</p>
  
  <pre><code>Year [7]
    [1] 1974
    [8] 1975
    [2] 1976
    [1] 1977
    [2] 1984
    [2] 1985
    [3] 1994
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-01-12T02:01:59.280Z
Answers.LastActivityDate: 2017-01-12T02:01:59.280Z
Answers.UserDisplayName: unor
Body: <p>In Calibre, I created a custom column with the type "Date". While it gets displayed as column in the ebook list, it does not appear in the tag browser.</p>
  
  <p><strong>Is there a way to have a date-based column as category in the tag browser?</strong></p>
  
  <p>It would be great to be able to filter ebooks by years, e.g.:</p>
  
  <pre><code>Year [7]
    1970s [4]
      [1] 1974
      [8] 1975
      [2] 1976
      [1] 1977
    1980s [2]
      [2] 1984
      [2] 1985
    1990s [1]
      [3] 1994
  </code></pre>
  
Tags: <calibre><metadata>
Title: Can a custom column with "Date" type be added to the tag browser?
UserDisplayName: unor
ThreadText: # Can a custom column with "Date" type be added to the tag browser?
  
  (Asked by: username_0 on 2017-01-12)
  
  In Calibre, I created a custom column with the type "Date". While it gets displayed as column in the ebook list, it does not appear in the tag browser.
  Is there a way to have a date-based column as category in the tag browser?
  It would be great to be able to filter ebooks by years, e.g.:
  Year [7]
    1970s [4]
      [1] 1974
      [8] 1975
      [2] 1976
      [1] 1977
    1980s [2]
      [2] 1984
      [2] 1985
    1990s [1]
      [3] 1994
  
  **Tags:** calibre, metadata
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2017-04-03. Score: 4
  
  Yes, you can accomplish that using SubGroups in Calibre. The way to do a subgroup is described here (for user entered Genres) but I'll do the TL;DR below for how to do it with publication dates: <https://manual.calibre-ebook.com/sub_groups.html>
  
  1. Create a custom column with desired lookup name (yearpub) and heading and give the column type "Column built from other columns, behaves like tags"
  2. In the Template box, enter this code: `{pubdate:'test($,
     strcat(substr(format_date($,'yyyy'), 0, 3), '0.',format_date($,'yyyy')),
     'Unknown')'}`
  3. Set "Sort/search columb by" to TEXT and mark a check in the "Show in tags browser".
  4. After restarting Calibre, go to Preferences-->Look and Feel-->Tag Browser and in the entry "Categories with hierarchical items" enter your custom column's lookup name.
  
  Now, what that all does is takes the Published Date data of that book/entry and puts it in the format of an hierarchical tag by decade.year which will now show in the Tags Browser under the lookup name you gave, then the decade, then the year. All without having to enter in any extra data! Just make sure the published date is correct. If no published date is given it will mark it as Unknown.
  
  Enjoy!
  
  
  ---
  
  ### Answer by username_0 on 2017-01-12. Score: 2
  
  It seems that this is not directly possible, but you can add an additional column to achieve something like this:
  
  Go to Preferences → Add your own columns
  Add custom column:
  
  Give it a name and a heading (this will be displayed in the tag browser)
  Select Column built from other columns
  Under "Template", enter the name of the date-based column you want to display, e.g.: 
  {#originalpublicationyear}
  
  Enable Show in tags browser
  OK
  
  Apply and restart Calibre
  
  Now this new column should be displayed as category in the tag browser. 
  Note that you can hide it as column in the book list, it will still work in the tag browser.
  Grouping (sub-categorization)
  Unfortunately, the grouping is not really helpful, because it uses only the year’s first character like "1" and "2" (in case of "By first letter"), or a range like "1985 - 1997" and "1997 - 2014" (in case of "Partition"). 
  In the first case, filtering by group doesn’t seem to work correctly, and in the second case filtering isn’t possible by design.
  So you might want to exclude this category from partitioning (under: Preferences → Look and Feel → Tag Browser), in which case you get a simple list:
  Year [7]
    [1] 1974
    [8] 1975
    [2] 1976
    [1] 1977
    [2] 1984
    [2] 1985
    [3] 1994
  
  
  ---
  
  