# Populating a table with data

Tables can be created from a range of input data structures. If you have seen the tutorial you will have seen a `QuerySet` being used, however any iterable that supports `len()` and contains items that exposes key-based access to column values is fine.

## List of dicts

In an example we will demonstrate using list of dicts. When defining a table it is necessary to declare each column:

    import django_tables2 as tables

    data = [
        {"name": "Bradley"},
        {"name": "Stevie"},
    ]

    class NameTable(tables.Table):
        name = tables.Column()

    table = NameTable(data)

## QuerySets

If your build uses tables to display `QuerySet` data, rather than defining each column manually in the table, the `Table.Meta.model` option allows tables to be dynamically created based on a model:

    # models.py
    from django.contrib.auth import get_user_model
    from django.db import models

    class Person(models.Model):
        first_name = models.CharField(max_length=200)
        last_name = models.CharField(max_length=200)
        user = models.ForeignKey(get_user_model(), null=True, on_delete=models.CASCADE)
        birth_date = models.DateField()

    # tables.py
    import django_tables2 as tables

    class PersonTable(tables.Table):
        class Meta:
            model = Person

    # views.py
    def person_list(request):
        table = PersonTable(Person.objects.all())

        return render(request, "person_list.html", {
            "table": table
        })

This has a number of benefits:

- Less repetition

- Column headers are defined using the field’s `verbose_name`

- Specialized columns are used where possible (e.g. `DateColumn` for a `DateField`)

When using this approach, the following options might be useful to customize what fields to show or hide:

- `sequence` – reorder columns (if used alone, columns that are not specified are still rendered in the table after the specified columns)

- `fields` – specify model fields to include

- `exclude` – specify model fields to exclude

These options can be specified as tuples. In this example we will demonstrate how this can be done:

    # tables.py
    class PersonTable(tables.Table):
        class Meta:
            model = Person
            sequence = ("last_name", "first_name", "birth_date", )
            exclude = ("user", )

With these options specified, the columns would be show according to the order defined in the `sequence`, while the `user` column will be hidden.

## Performance

Django-tables tries to be efficient in displaying big datasets. It tries to avoid converting the `QuerySet` instances to lists by using SQL to slice the data and should be able to handle datasets with 100k records without a problem.

However, when performance is degrading, these tips might help:

1. For large datasets, try to use `LazyPaginator`.

2. Try to strip the table of customizations and check if performance improves. If so, re-add them one by one, checking for performance after each step. This should help to narrow down the source of your performance problems.