Calculate reading time.

[dunhill]

Hello, people could help me with this:
I have two custom columns with the read start date and the end date, I want to calculate the time.
use days_between (field ('#fin'), field ('#ini'))
but in the caampo it gives me back this synthesis, I leave screenshots in case I'm doing something wrong.
Thank you.

https://ibb.co/ZzBXZCk
https://ibb.co/P5LJwqL
https://ibb.co/5BnTkgX

[dunhill]

I keep turning this issue around, apparently it's how Caliber establishes it, but it does not work for me.
I will miss some complement?

[chaley]

You must put

program:

in front of the days_between function. See the Template General Program Mode documentation.

[dunhill]

Originally Posted by chaley

You must put

program:

in front of the days_between function. See the Template General Program Mode documentation.

he came to my house and I try it, thank you very much

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Venia viajando y mi ingles no es muy bueno, perdón.
Lo que he puesto es que en cuanto llegara a mi hogar lo probaria.

[chaley]

Originally Posted by dunhill

he came to my house and I try it, thank you very much

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Sorry, but the translation of your post (from Spanish? Portuguese?) makes no sense. Could you also post the original phrase in your language so we can try to figure out what you are really saying?

[davidfor]

@chaley: I assume he meant "I tried it here and it didn't work.

@dunhill: The following is working here:

program:
days_between(field('last_modified'),field('#last_seen'));

I only have the one date custom column in the library I have here. But, it worked with the Date a Published date columns as well (once I typed their names in correctly .


And as an aside, I absolutely hate the fact that changing the template for a column changes the modified date for all books in the library. The same goes for adding a new column. Or even changing the column header. I've handled that in the source at home, but, I don't run from source on my work machine.

[chaley]

Originally Posted by davidfor

And as an aside, I absolutely hate the fact that changing the template for a column changes the modified date for all books in the library. The same goes for adding a new column. Or even changing the column header. I've handled that in the source at home, but, I don't run from source on my work machine.

Using the preferences editor changes the last modified date. Try editing the template from the booklist using F2 of any row of the column. IIRC that doesn't change the last modified date.

The rationale for changing the last modified date is to be sure that the backup OPF files are up to date. This is a rather complicated question, so the default is "any change requires a new backup".

[davidfor]

Originally Posted by chaley

Using the preferences editor changes the last modified date. Try editing the template from the booklist using F2 of any row of the column. IIRC that doesn't change the last modified date.

That was what I was doing when I noticed modified time changing. I was thinking it didn't change, but it did this time.

The rationale for changing the last modified date is to be sure that the backup OPF files are up to date. This is a rather complicated question, so the default is "any change requires a new backup".

The only problem with that is that the only time I needed to restore from the backup OPF files, it didn't restore the custom columns. This was for my wife's library and she only had one or two custom columns that didn't have much in them. I've been meaning to look at what went wrong, but I did follow the instructions in https://manual.calibre-ebook.com/faq...libre-is-blank. (OK, I did what I thought should work and then read the manual.) Or have I misunderstood what should happen?

From my point of view, if I add an extra column, then the backup OPF doesn't need to be updated until I populate it with a value. And the library backup status dialog has a button to "Queue all books for backup". Isn't it a matter of triggering that whenever a change is made? Except that it appears to work by changing the modified date for all books (ouch). But, it also appears to work based on the contents of the table "metadata_dirtied". I'm assuming that an entry is added to that table whenever book is modified. Finding another way to populate that after a custom column change, or pressing that button above should do what is desired. I'm sure it won't be as simple as that, but, it will be interesting to see what is needed.

A lot of the frustration with this is that I have been involved in a lot of database migrations and changes over the years. What happens with the the created dates and last modified dates is always something that gets discussed. And frequently we have to do something to prevent them from being changed.

[dunhill]

@chaley
@davidfor

I am reading your comments carefully.

Thanks to run with the word program. It has been overlooked. several eyes see better than two.
I have changed the format so that I do not get the result in decimals with this syntax:
program: format_number (days_between (field ('#dateendded'), field ('# goodreadsstarted1')), "{0: 5.0f}")
I must revise, similarly because with some dates it does not calculate me and they are loaded in the same way.

[davidfor]

Originally Posted by dunhill

@chaley
@davidfor

I am reading your comments carefully.

Thanks to run with the word program. It has been overlooked. several eyes see better than two.
I have changed the format so that I do not get the result in decimals with this syntax:
program: format_number (days_between (field ('#dateendded'), field ('# goodreadsstarted1')), "{0: 5.0f}")
I must revise, similarly because with some dates it does not calculate me and they are loaded in the same way.

Sorry, I don't know what is happening there. The two things I'd try would be restarting calibre or editing one of the dates.

[chaley]

Originally Posted by davidfor

That was what I was doing when I noticed modified time changing. I was thinking it didn't change, but it did this time.

My bad. It does change the time. The advantage is that it doesn't force a calibre restart

The only problem with that is that the only time I needed to restore from the backup OPF files, it didn't restore the custom columns. This was for my wife's library and she only had one or two custom columns that didn't have much in them. I've been meaning to look at what went wrong, but I did follow the instructions in https://manual.calibre-ebook.com/faq...libre-is-blank. (OK, I did what I thought should work and then read the manual.) Or have I misunderstood what should happen?

It is supposed to work, and does work in my tests.

The only failure mode that I can think of that would cause the loss of custom columns is if the metadata_db_prefs_backup.json file is corrupt, missing the custom column definitions. If the entire file is missing then the column metadata is rebuilt from the OPF files. If "field_metadata" JSON inside the file is missing then the same thing happens. However, if the field_metadata field is there but missing the custom column metadata then the columns are lost.

From my point of view, if I add an extra column, then the backup OPF doesn't need to be updated until I populate it with a value. And the library backup status dialog has a button to "Queue all books for backup". Isn't it a matter of triggering that whenever a change is made? Except that it appears to work by changing the modified date for all books (ouch). But, it also appears to work based on the contents of the table "metadata_dirtied". I'm assuming that an entry is added to that table whenever book is modified. Finding another way to populate that after a custom column change, or pressing that button above should do what is desired. I'm sure it won't be as simple as that, but, it will be interesting to see what is needed.

The goal was to ensure that the OPF file contains the column definitions. Values in the file aren't used except for composite column templates.

[chaley]

Originally Posted by dunhill

@chaley
@davidfor

I am reading your comments carefully.

Thanks to run with the word program. It has been overlooked. several eyes see better than two.
I have changed the format so that I do not get the result in decimals with this syntax:
program: format_number (days_between (field ('#dateendded'), field ('# goodreadsstarted1')), "{0: 5.0f}")
I must revise, similarly because with some dates it does not calculate me and they are loaded in the same way.

Also use "raw_field" instead of "field", just in case the dates are formatting in a way that calibre cannot handle.

[dunhill]

Originally Posted by chaley

Also use "raw_field" instead of "field", just in case the dates are formatting in a way that calibre cannot handle.

Thank you.

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