drtomc/barc repository overview

⁠barc - make sheets of barcode labels.

For various kinds of inventory management, it is convenient to be able to create neatly formatted pages with labelled barcodes. For example, using a domestic inventory management system such as Grocy⁠, we can:

• make pages of barcode labels to stick on goods when we put them in the freezer
• make a laminated sheet of common goods, such as fruit, for onvenient scanning

For use cases like the first, we want to make a sheet of labels with the same barcode repeated, or perhaps half a sheet of one barcode, and half a sheet of another. For the second case, we simply want to have a sheet with many different labels, once each.

Barc is a tool for doing exatly these tasks. It works by reading a YAML⁠ specification for the page of labels, and producing an HTML file using CSS⁠ to arrange the barcodes and text so they can be printed to suit sticky label sheets such as those from Avery⁠. To render the HTML+CSS accurately, we like Prince⁠ (Especially as it is made by a local company!), and use it in the docker container for Barc.

The YAML for specifying a page of labels has the following form:

version: '1'
options:
  barcode-type: <<barcode-type>>
  style: <<CSS styling to use>>
barcodes:
- - code: 123456789             # first row, first column
    label: 'Apple, green'
  - code: 234567890             # first row, second column
    label: 'Apple, red'
  ...
- - code: 567890123             # second row, first column
    label: 'Orange, Seville'
  ...

If no barcode type is given, code128 is assumed.

If a style is given, it is added to the HTML with a link element.

It is assumed you know the number of rows and columns for your sheet of labels, the dimensions of which will be described in the CSS.

Both the code and label in the specification are optional - the following rules are applied:

• If the code is not specified but the label is, the label is used as the code.
• If the label is not specified, but the code is, the code is added as a label.
• If the code is the empty string, or neither the code or label are given then a random code is generated.

⁠YAML Anchors and References

If you are making a sheet of labels which are all the same, the YAML can become quite verbose, and awkward to modify. However, YAML contains a nifty mechanism to allow you mark a part of the document tree, and refer to it subsequently. For example, suppose we want to make a page of barcodes for packages of chicken breasts for the freezer, we might have a specification like the following:

version: '1'
options:
  barcode-type: code128
  style: /style/L7160
barcodes:
- - code: CHICKBRST
    label: Chicken Breast
  - code: CHICKBRST
    label: Chicken Breast
  - code: CHICKBRST
    label: Chicken Breast
- - code: CHICKBRST
    label: Chicken Breast
  - code: CHICKBRST
    label: Chicken Breast
  - code: CHICKBRST
    label: Chicken Breast
...

YAML allows us to attach a label to the {code: ..., label: ...} map node, and then refer to it after:

version: '1'
options:
  barcode-type: code128
  style: /style/L7160
barcodes:
- - &CB code: CHICKBRST
    label: Chicken Breast
  - *CB
  - *CB
- - *CB
  - *CB
  - *CB
...

But we can go further, and attach a label to the row, and then replicate the row:

version: '1'
options:
  barcode-type: code128
  style: /style/L7160
barcodes:
- &ROW [&CB {code: CHICKBRST, label: 'Chicken Breast'}, *CB, *CB]
- *ROW
- *ROW
- *ROW
- *ROW
- *ROW
- *ROW

With this brief form, the above YAML yields a full sheet of 21 (3x7) L7160 labels. (Note we switched between the layout form and the inline form of the YAML for the row.)

⁠Docker

We have packaged up barc in a docker image with prince to make it really easy to make barcode labels. It has pre-packaged styles in /style/<<format>>, and by default runs on each YAML file in /data to create the HTML and PDF files for the labels specified in the YAML file.

To run it, you will want to use volumes to add your YAML files to the container, and to pick up the generated files.

For example:

$ ls -lh my-data
total 4.0K
-rw-rw-r-- 1 tom tom 159 Jun 21 20:38 chicken.yaml
$ cat my-data/chicken.yaml
version: '1'
options:
  barcode-type: code128
  style: /style/L7160
barcodes:
- &ROW [&CB {code: CHICKBRST, label: 'Chicken Breast'}, *CB, *CB]
- *ROW
- *ROW
- *ROW
- *ROW
- *ROW
- *ROW
$ docker run -v ${PWD}/my-data/:/data/ drtomc/barc
$ ls -lh my-data/
total 56K
-rw-r--r-- 1 root root 26K Jun 21 20:47 chicken.html
-rw-r--r-- 1 root root 22K Jun 21 20:47 chicken.pdf
-rw-rw-r-- 1 tom  tom  186 Jun 21 20:47 chicken.yaml

Note you may run into permissions problems, and need to do something like the following:

$ sudo chown tom:tom my-data