Snippets by Lacour

ByteSplitterField

When you want to save integers to the db, you usually have the choice between 16-, 32- and 64-bit Integers (also 8- and 24-bit for MySQL). If that doesn't fit your needs and you want to use your db-memory more efficient, this field might be handy to you. Imagine you have 3 numbers, but need only 10 bit to encode each (i.e. from 0 to 1000). Instead of creating 3 smallint-fields (48 bit), you can create one 'ByteSplitterField' which implements 3 'subfields' and automatically encodes them inside a 32 bit integer. You don't have to take care how each 10-bit chunk is encoded into the 32-bit integer, it's all handled by the field (see also field's description). Additionally, the Field offers opportunity to use decimal_places for each of your subfields. These are 'binary decimal places', meaning the integer-content is automatically divided by 2, 4, 8, etc. when you fetch the value from the field. You can also specify how values are rounded ('round' parameter) and what happens when you try to save a value out of range ('overflow' parameter) Not implemented (maybe in the future if I should need it sometime): * signed values. All values are positive right now! * real (10-based) decimal places (actually you could probably directly use DecimalFields here) * further space optimization, i.e. saving into CharField that's length can be chosen byte-wise

• model
• db
• database
• field
• custom
• custom-model-field
• IntegerField
• multibit-field
• model-field

Sat 27 Aug 2011 Read More

TinyIntegerField

Django lacks support of MySQL's "tinyint" 8-bit-integer datatype. This snippet gives you a TinyIntegerField and a PositiveTinyIntegerField. Falls back Django's SmallIntegerField if a different database-engine is used

• model
• db
• 8-bit-integer
• MySQL
• IntegerField
• tiny-integer

Mon 17 Mar 2014 Read More

Dynamically add css-classes to formfields

This example assumes you have a form and want to highlight one of two fields by setting <class="highlight"> in the html dynamically. This is an alternative to <https://docs.djangoproject.com/en/1.3/ref/forms/widgets/#customizing-widget-instances>, but now you're not limited to assigning the class to the fields html-output, instead you can also assign it to a div around the field like done here. After assigning a css-attribute to a field, we access the css via a templatefilter *{{ field|css }}* that looks up *field.form.fields[field.name].css* and not simply *field.css*, since the latter would try to access a non-existing css-attribute on a BoundField-instance EDIT: The templatefilter is unnecessary. There is a much easier way, since the original field itself is an attribute of the BoundField named 'field'. So in the template, we can access the css via {{ field.field.css }}. Thanks to Tom Evans for pointing me at this.

• css
• form
• class
• dynamic-form
• formfield
• dynamic-css
• css-class

Fri 15 Jul 2011 Read More

Checkbox or radio iterator as template filter

This snippet is based on [Bill Freeman's MultiSelect checkbox iterator template filter](http://djangosnippets.org/snippets/2151/). Usage: See docstring

• checkbox
• choice
• templatefilter
• iterator
• checkbox-input
• form-choice
• radio-button
• radio-input

Fri 30 Dec 2011 Read More

Form and FormSet that are defined dynamically with request-data

This is how you can access the user's request in the Form or FormSet definition, e.g. to define the choices of a ChoiceField dynamically. Either you use it for a single Form or a whole FormSet, just pass the view's request into the Form or FormSet instantiation.

• form
• request
• formset

Tue 21 Jun 2011 Read More