pdffiller-script

Scripted PDF form filling. This project is inspired by pdffiller, but needed something more powerful and flexible to allow filling out many forms with data from a single input configuration file, but also allowing values to be manipulated / computed before form filling. For example, to combine first and last names, or to ensure currency values look like currency values.

This pdffiller-script depends on pdffiller and has a dependency on the PDF Toolkit.

your.first.name.and.middle.initial:
  6: ctx.identity.firstName + (ctx.identity.middleName ? ` ${ctx.identity.middleName[0]}`:'')

From the API, the engine is extensible.

Install

To install pdffiller-script to use the module API.

$ npm install pdffiller-script

Install pdftk

sudo apt-get install pdftk

CLI usage

Generate map file and example YAML files

Parse the PDF and generate the map file, and example files to aid in form filling:

$ npx pdffiller-script map mypdf.pdf

This command generates mypdf-map.yaml which will later be fed into the CLI for filling out the PDF form. It also generates a number of example files to aid in form filling.

mypdf-map.yaml: Maps input fields to integer values. Referred to as the "map".

mypdf-example-script.yaml: An example form filler script. Referred to as the "filler script". Fills all fields to "todo" (values read from the config file). ⚠️ refer to filler doc.

mypdf-example-config.yaml: An example configuration that sets every value to "todo". ⚠️ refer to config doc.

mypdf-example-filled.pdf: The PDF file filled with each field containing an incremental integer value for easier identification of fields to fill.

Fill a PDF

If you wish, you can modify mypdf-example-config.yaml and change a few values. Ultimately, you will create custom config and script files. Then, run the filler script and produce a PDF:

$ npx pdffiller-script fill mypdf.pdf \
 --map mypdf-map.yaml\
 --config mypdf-example-config.yaml\
 --filler mypdf-example-script.yaml\
 --output output.pdf

Scripted PDF form filling

The pdffiller-script uses pdffiller to interact with PDF forms, which makes it super easy to fill forms. However, not all forms have friendly keys. For example, the USA IRS f1040 forms have keys that are not very user friendly, making correlating the field IDs to the form extremely difficult. Furthermore, they are different on every form, there are lots of forms, and lots of fields. If you were to use pdffiller, you would have quite a job. The pdffiller-script simplifies that by employing a mapping system that uniquely identifies fields, and providing a configurable and scriptable interface for filling PDF forms.

For example, take two fields from the f1040 form.

The two fields actually have these IDs:

These two fields exist on many (if not every) PDF tax form, and they have different keys. The idea behind pdffiller-script will abstract these fields by giving each field in a form a unique integer ID that maps to the actual form fields. It generates an example PDF file filled with the unique integer IDs so you can visually identify the fields you wish to fill.

Then, it becomes much easier to keep track of fields, and build a form filler script that is used to dynamically set values in the form. For example:

# f1040-filler.yaml
fill_first_name:
  6: ${ctx.firstName}
fill_last_name:
  7: ${ctx.lastName}

In the script above, the fill_first_name key must be unique, but it is almost completely arbitrary (more on that later). The key helps the script maintainer identify the field by something other than the integer ID. The 6 indicates that this script will fill field with ID 6 (the Your first name and middle initial field).

The ${ctx.firstName} is a JavaScript template literal. The ctx is from the config file that you customized:

# config.yaml
firstName: Joe A
lastName: Bloggs

After running the script, it will fill the form, and evaluate ${ctx.firstName} as "Joe A" and assign it to the input field, topmostSubform[0].Page1[0].f1_02[0]. Then, it will do the same for ${ctx.lastName}, yielding:

Example

For use with the ./example provided with the source.

Generate an f1040 map file

This will re-generate the example/f1010-map.yaml file and examples. If you only want the map, use the option --no-example.

$ npx pdffiller-script map example/f1040.pdf --out "example"

Fill out an f1040 form

$ npx pdffiller-script fill example/f1040.pdf \
  --map example/f1040-map.yaml \
  --config example/config.yaml \
  --script example/f1040-filler.yaml \
  --output output.pdf

Fill out an f1040 form via the programmatic API

$ cd example
$ node fill-f1040.js

Filler script API

The form filler script is a YAML file that is generated using the map CLI.

Types of inputs

• Fixed-field inputs are used when there is a 1:1 correlation between the field ID and the config value.
• Calculated inputs are used when the either field ID or value to fill depends on the config value.

Fixed-field inputs

When there is direct correlation between the config value and an input field, then the fixed-field input is the optimal choice. Fixed-field inputs have the syntax:

unique.friendly.key:
  integer: value

The key is a unique friendly key, unique.friendly.key, is (almost) completely arbitrary (see Script friendly keys). It is used to help the script maintainer to correlate the value back to the form without having to look at the form.

The integer is the unique integer ID assigned to the field. It can be seen in the example filled PDF that was generated when it built the map. It is also in the map file that was generated. In this way, it is a fixed-field input because the field ID is known in advance.

The value is described in Script values.

Calculated inputs

When either the field ID or the value to fill depends on the config value, then it is necessary to use a field calculated. Calculated inputs have the syntax:

unique.friendly.key:
  value: value
  calculate: |
    (ctx, val) => { field, fill }

Sometimes the exact field ID to fill or the ultimate value to input may not be known in advance. An example of this might be one of several check-boxes or radio buttons (these can be very difficult to figure out by the way, see troubleshooting). For example, consider a form with radio buttons:

Favorite fruit:
  ( ) Apple
  ( ) Banana

The config might be:

fruit: banana

However, the "Apple" and "Banana" radio buttons have different input ID. Depending on the config, there are one of two different inputs to fill. The solution is to calculate both the ID and the input value to fill, based on the config value. For example:

favorite.fruit:
  value: ${ctx.fruit}
  calculate: |
    (ctx, val) => {
      if (val === 'banana') {
          return { field: 1, fill: '0' };
      } else {
          return { field: 2, fill: '1' };
      }
    }

The calculation scripts are by-far the most difficult aspect of form filling. You need to know your way around JavaScript, and it can be tricky figure out exactly what value will enable/disable a particular check-box or radio (if anyone has insight into this, please let me know).

Script values

The value is computed as a JavaScript template literal. It can be constant value, e.g. "Joe Bloggs" or 1234.00. However, JavaScript can the Javascript Core Objects also be used within the script. In addition, there is a pre-defined context, ctx, that allows the script to access the configuration file.

fill.string:
  0: Joe Bloggs
fill.number:
  0: 1234.00
fill.first.last:
  0: ${ctx.firstName} ${ctx.lastName}
fill.js:
  # fill an ISO 8601 string "2020-04-13T12:31:23.799Z"
  0: ${new Date().toISOString()}

In addition, there are a number of built-in helper functions that can help clean and sanitize data.

Script friendly-key convention

We said that the friendly keys are mostly arbitrary. There are a number of built-in helper functions that can help clean and sanitize data. However, they are not too convenient if used a lot. For example, imagine filling out a form that required large amounts of monetary input, but that the input be rounded to a whole number (no decimal places). It would be inconvenient to repeatedly write this every time a whole number was required:

total.income:
  0: ${currencyWhole(ctx.totalIncome)}

It is more convenient to add a suffix and automatically apply a function, e.g.:

total.income.whole:
  0: ${ctx.totalIncome}

The shorthand suffixes make repetitive inputs more convenient. However, using them has an added drawback when referring to Previously filled fields. The API has a way to add additional helper functions and shorthand keys.

Suffix .currency

If the friendly key ends with .currency, then the value will be automatically converted with the currency helper function.

fill.number.currency:
  # fills "1,234.00"
  0: 1234

Suffix .whole

If the friendly key ends with .whole, then the value will be automatically converted with the currencyWhole helper function.

fill.number.whole:
  # fills "1,234"
  0: 1234.00

Suffix .dec

If the friendly key ends with .dec, then the value will be automatically converted with the currencyDec helper function.

fill.number.dec:
  # fills "00"
  0: 1234.00

Suffix .nodash

If the friendly key ends with .nodash, then the value will automatically be stripped of any - dash characters.

fill.number.dec:
  # fills "1234"
  0: 12-34

Script helper functions

currency(number)

Converts the value to a currency value with thousand separators and decimal fraction (without any specific currency designator) using the locale of the operating system. Unexpected string values will return "NaN" and undefined and null values will return 0.

currencyWhole(number)

Converts the value to a whole currency value with thousands separators, but no decimal fraction (without any specific currency designator) using the local of the operating system. Unexpected string values will return "NaN" and undefined and null values will return 0.

currencyDec(number)

Returns the decimal fraction of a currency (without the leading decimal separator) using the local of the operating system. Unexpected string values will return "NaN" and undefined and null values will return 00.

parseCurrency(string)

Parses a currency (ignoring thousand separators) and returns a number with decimal fraction (if present). E.g. "1,234.56" will return "1234.56".

strCapitalize(string)

Capitalizes the first letter of a string.

strNoDash(string)

Removes all dashes from a string, e.g. SSN or phone numbers.

strTrim(string)

Removes all leading and trailing whitespace around a string.

Previous filled fields

It is possible to access previous filled fields through the ctx by accessing the ctx.forms by name.

adjusted.income.currency:
  0: ${ctx.forms['business'].totalIncome - ctx.forms['business'].expenses}