Django Decimal field with value Decimal(0.00) is displayed as 0E-10 in the Django Admin Inline

Question

Django 2.2. Model Definition.

class BlockPeriod(BaseModel):
    price = models.DecimalField(max_digits=20, decimal_places=10)
    margin = models.DecimalField(max_digits=20, decimal_places=10)

If the user saves margin or price as "0" it would be displayed as "OE-10" on the next page load.

Screenshot is from DjangoAdmin.

I want to display 0 or 0.00 instead of OE-10 in margin and price fields.

Thanks

Answer 1

If you only want to display 2 places, you can simply set decimal_places to 2.

class BlockPeriod(BaseModel):
    price = models.DecimalField(max_digits=20, decimal_places=2)
    margin = models.DecimalField(max_digits=20, decimal_places=2)

You can also consider using a FloatField which leads to 0.0 as representation for 0.

float_value = models.FloatField()

Answer 2

The way out of it was adding form fields price and margin with decimal places set to 6. For any number higher Django renders inline fields with html step "1e-7","1e-8", "1e-9"... I wanted to keep 10 decimal places on DB level.

Answer 3

I solved this by creating a custom admin form widget that replaces 0E-10 with 0 using JavaScript. Here is the Django part:

from django import forms
from django.contrib import admin

class BlockPeriod(BaseModel):
    price = models.DecimalField(max_digits=20, decimal_places=10)
    margin = models.DecimalField(max_digits=20, decimal_places=10)

class DecimalWidget(forms.widgets.NumberInput):
    class Media:
        js = ('js/decimal_widget.js', )
        
class BlockPeriodAdminForm(forms.ModelForm):
    class Meta:
        widget = DecimalWidget(attrs={'class': 'decimal-widget'})
        widgets = {'price': widget, 'margin': widget}
        fields = '__all__'

class BlockPeriodAdmin(admin.ModelAdmin):
    form = BlockPeriodAdminForm

admin.site.register(BlockPeriod, BlockPeriodAdmin)

Then somewhere under static/js/decimal_widget.js (your file location may be different) you would have this JavaScript:

function convertDecimalValues() {
  $('input.decimal-widget').each(function() {
    if (this.value == '0E-10') { this.value = 0; }
  });
}

$(document).ready(function() {
  convertDecimalValues();
});

I will be the first to admit that this feels like an overkill, and there should be an easier way to do this. But this does the trick.