Iterate over row columns

Anvil Q&A
#1

Hi, I’m trying to put together a “smart search” field that will look for a substring in each text column of a row.

How can I iterate over the columns of a row without specifying their names (or is there a command to get a list of all available columns and their types from the iterator)?

#2

A row is essentially a Python dictionary (type dict). Standard dict iteration features should apply.

#3

You can experiment with print() to get various “parts” of rows’ structure. You can iterate through column names like this (or invent something more pythonic :grinning:):

  rows = app_tables.some_table.search()
  for row in rows[0]:
    print(row[0])
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#4

You can call app_tables.my_table.list_columns() to get a list of all the column names for a table. This doesn’t expose the types of these columns, but it does allow you to at least enumerate the columns efficiently :slight_smile:

(More info in the data tables API docs)

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#5

This post was very helpful! I could not find this in the reference docs, or in the tooltip/autocomplete prompt in the code view. (I’m not sure if it needs to be in either, but just thought I’d mention)

Also, this function appears to give a list of dicts, where each item of the list is a dict of (column data type, column name).

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#6

Adding to this old thread in case anyone else wanting to iterate over RowObject ended up here as I did. This was the only thread Google provide and the answers weren’t quite what I needed, but they were enough to point me in the right direction.

I wanted to use a row object in a dictionary comprehension. So something like:

my_copy = {k:v for k,v in self.item.items()}

where self.item was a <LiveObject: anvil.tables.Row>

Alas it cannot be done like that as an anvil.tables.Row doesn’t have a items method. Nor can you cheat with:

my_copy = {k:self.item[k] for k in self.item}

In this case the items returned are a tuple where element at index 0 is the column name, index 1 is the value.

So do actually achieve what I wanted the required code was:

my_copy = {k[0]:k[1] for k in self.item}
#7

Since you’re trying to make a dict, you might try something like:

my_copy = dict(self.item)
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#8

Thanks, I’ll keep that in mind if I need a full copy.
Using the dictionary comprehension allowed me to be picky about the things I copied. I didn’t include it in the example as I was giving a minimal example to illustrate.

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