Data Model¶

In the typical scenario, the master view’s model_class is set to a data model which maps to a table in the app database. For instance:

from wuttjamaican.db.model import Person
from wuttaweb.views import MasterView

class MyPersonView(MasterView):
    model_class = Person

With a mapped model class, the view can inspect the class to derive the model name, title, etc. In particular it can determine the model “key” automatically, which is used in the URL to identify a given record. This is just uuid for normal mapped models.

But the “model” can really be any tabular data set; for instance you could have a master view which showed the file contents of a folder on disk. In such “ad-hoc” scenarios the model data can just be a list of dicts. In that case instead of setting model_class you would just set model_name, but you also must set the model_key since that cannot be determined from introspection:

from wuttaweb.views import MasterView

class SpecialFileView(MasterView):
    model_name = "special_file"
    model_key = "filename"

In any case you may also want to set/override the model_title and model_title_plural:

from wuttaweb.views import MasterView

class SpecialFileView(MasterView):
    model_name = "special_file"
    model_key = "filename"
    model_title = "Special File"
    model_title_plural = "Special Files"

If the view has a mapped model_class then it should already have logic needed to fetch data for the grid and CRUD interfaces. But in the ad-hoc scenario you must define methods to handle that:

import os
from wuttaweb.views import MasterView

class SpecialFileView(MasterView):
    model_name = "special_file"
    model_key = "filename"

    SPECIAL_DIR = "/tmp"

    def get_grid_data(self, **kwargs):
        """
        Override parent method to define how the full data set can
        be fetched.
        """
        data = []
        for fname in os.listdir(self.SPECIAL_DIR):
            fpath = os.path.join(self.SPECIAL_DIR, fname)
            if os.path.isfile(fpath):
                data.append(self.normalize_file(fname))
        return data

    def get_instance(self, **kwargs):
        """
        Override parent method to define how a single "instance"
        (record) can be fetched.
        """
        # nb. the 'filename' (key) is embedded in current page URL
        fname = self.request.matchdict["filename"]
        fpath = os.path.join(self.SPECIAL_DIR, fname)
        if not os.path.isfile(fpath):
            raise self.notfound()
        return self.normalize_file(fname)

    def normalize_file(self, fname):
        """
        Helper method to ensure grid/instance use the same logic to
        construct data records.
        """
        fpath = os.path.join(self.SPECIAL_DIR, fname)
        return {
            "filename": fname,
            "filepath": fpath,
            "filesize": os.path.getsize(fpath),
        }

A master view can also define a row model which would represent a “secondary” data set associated with a single primary instance/record. But we’ll get into more detail on that later.

Here are most of the relevant docs for customizing the primary data model:

Model Proper

Fetching Data