Translating Values

The Problem

Sometimes, you need to translate a value before it’s rendered; perhaps to convert a string to a Python datetime instance, or to format a number a particular way.

In this case, let’s say we want to write a table with the following data but the email addresses must be censored:

[
    {
        "name": "Robert Pringles",
        "email": "bob@pringles.pop"
    },
    {
        "name": "Daniel Sausage",
        "email": "danny@pringles.pop"
    },
    {
        "name": "Charlie Marmalade",
        "email": "charlie@pringles.pop"
    }
]

We’ll achieve this by passing a translator into the Email column.

Code Sample

This code is similar to the Flat Table example except for the Source being passed into the Email column. In the previous example, we passed in only the path; this is shorthand for a Source with only a path. Now, we pass in both the path and translator as a Source instance.

from rolumns import Columns, Source, TranslationState
from rolumns.renderers import RowsRenderer

def censor(state: TranslationState) -> str:
    return (
        state.value[0]
        + "".join(["*" * (len(state.value) - 2)])
        + state.value[-1]
    )

data = [
    {
        "name": "Robert Pringles",
        "email": "bob@pringles.pop"
    },
    {
        "name": "Daniel Sausage",
        "email": "danny@pringles.pop"
    },
    {
        "name": "Charlie Marmalade",
        "email": "charlie@pringles.pop"
    }
]

columns = Columns()
columns.add("Name", "name")
columns.add("Email", Source("email", translator=censor))

renderer = RowsRenderer(columns)
rows = renderer.render(data)

print(list(rows))

Result

 [['Name',              'Email'],
  ['Robert Pringles',   'b**************p'],
  ['Daniel Sausage',    'd****************p'],
  ['Charlie Marmalade', 'c******************p']]