please format the code at the bottom
On Tue, Dec 6, 2016 at 2:11 PM, Mike Dewhirst <mi...@dewhirst.com.au> wrote:
> Consider a chemical mixture with a bunch of ingredients. Both mixture and
> ingredients are instances of the same class so they have the same fields.
> They also have many related models, including 1:1, 1:n and n:m.
>
> Each related model will have none or many TextField's.
>
> The objective is to programmatically fill empty mixture text fields with
> concatenated content from the ingredients. The concatenated content would
> be separated by ingredient name titles for the user to deal with the
> content more easily.
>
> I don't necessarily need all mixture text fields filled this way but it
> certainly makes sense for some. With a couple of related models I'd
> concatenate all text fields, with most though I'd like to pick and choose
> by field name and I'd ignore some models completely.
>
> The following model method is working properly as described but it is
> mostly boiler-plate. It also only covers the first few of a large number of
> related models with text fields. If I keep using this technique it will add
> hundreds of LOC. Yuk.
>
> The question is how can I refactor this and make it generic? Perhaps using
> the _meta API?
>
> Any guidance appreciated
>
>
> (In the abstract ancestor class of the Solid, Liquid and Gas classes) def
> concat_fields(self, ingredients): """ ingredients is a queryset of
> substance-to-substance m2m records. A substance has one physical state
> object being gas, liquid or solid each of which inherits from core_fields
> and the fields *here* we wish to concatenate text from (at the moment) all
> come from core_fields. """ assert ingredients # populate the list of
> ingredient physical state objects state_objs = list() for m2m in
> ingredients: # substance has physical state so it knows which model to
> return state_objs.append(m2m.ingredient.get_physical_state_object()) #
> get the text concatenated if not self.stability_comment: comment = "" for
> obj in state_objs: if obj.stability_comment: name = obj.substance.name
> text = obj.stability_comment comment = "{0}\n{1}: {2}".format(comment,
> name, text) comment = comment.strip() if comment: self.stability_comment =
> comment # and repeat if not self.reactivity: comment = "" for obj in
> state_objs: if obj.reactivity: name = obj.substance.name text =
> obj.reactivity comment = "{0}\n{1}: {2}".format(comment, name, text)
> comment = comment.strip() if comment: self.reactivity = comment # ad
> nauseam if not self.reaction_hazards: comment = "" for obj in state_objs:
> if obj.reaction_hazards: name = obj.substance.name text =
> obj.reaction_hazards comment = "{0}\n{1}: {2}".format(comment, name, text)
> comment = comment.strip() if comment: self.reaction_hazards = comment if
> not self.avoid: comment = "" for obj in state_objs: if obj.avoid: name =
> obj.substance.name text = obj.avoid comment = "{0}\n{1}:
> {2}".format(comment, name, text) comment = comment.strip() if comment:
> self.avoid = comment if not self.incompatibilities: comment = "" for obj in
> state_objs: if obj.incompatibilities: name = obj.substance.name text =
> obj.incompatibilities comment = "{0}\n{1}: {2}".format(comment, name, text)
> comment = comment.strip() if comment: self.incompatibilities = comment
>
> Thanks
>
> Mike
>
>
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