Jujens' blog

Some tips for django

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Easily increment migrations numbers
Create a widget with custom display

Easily increment migrations numbers

Here is a small bash script to increment the numbers of your migrations. Put it into your ~/.profile or ~/.bashrc. Use it like: inc-migrations PROJECT/apps/APP_NAME/migrations 0012

It will rename all migrations from 0012 (ie transform 0012_mig.py into 0013_mig.py and so on) and replace all occurrences of the previous name (eg 0012_mig.py) with the new one (eg 0013_mig.py).

function inc-migrations() {
    local folder="$1"
    local number="$2"
    local start_file
    local new_number
    local next_file

    if ! [[ "$(pwd)" =~ "${folder}$" ]]; then
        cd "${folder}"
    fi

    if [[ -f "${number}" ]]; then
        start_file="${number}"
        number=$(echo "${number}" | cut -d _ -f 1)
    else
        start_file=$(ls ${number}* 2> /dev/null)
    fi

    if [[ ! -f "${start_file}" ]]; then
        echo "${start_file} doesn't exits" >&2
        return 1
    fi
    let "new_number = ${number} + 1"
    new_number=$(printf "%04d\n" "${new_number}")
    next_file=$(ls ${new_number}* 2> /dev/null)

    new_file_name="${start_file/${number}/${new_number}}"
    git mv "${start_file}" "${new_file_name}"
    sed -i "s/${start_file/.py/}/${new_file_name/.py/}/g" *.py

    if [[ -f "${next_file:-}" ]]; then
        inc-migrations "${folder}" "${next_file}"
    fi
}

Create a widget with custom display

class BonusTimeWidget(AdminIntegerFieldWidget):
    UNITS_TO_TRANSLATIONS = {
        'month': partial(ungettext_lazy, '%(count)d month', '%(count)d free months'),
    }

    def __init__(self, *args, unit='month', **kwargs):
        super().__init__(*args, **kwargs)
        if unit not in self.UNITS_TO_TRANSLATIONS:
            supported_units = ','.join(self.UNITS_TO_TRANSLATIONS.keys())
            raise ValueError(
                f'{unit} is not a supported unit. Supported units are: {supported_units}',
            )

        self.bonus_translation = self.UNITS_TO_TRANSLATIONS[unit]

    def render(self, name, value, attrs=None):
        """Render the value in a custom span."""
        if value == 0:
            return ''

        text = self.bonus_translation(value) % {'count': value}
        return mark_safe(f'<span>+ {text}</span>')

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