List Objects documentation has some errors

I noticed a few issues with the code example on http://gophercloud.io/docs/object-storage/#list-objects

Currently, it shows:

List objects

import "github.com/rackspace/gophercloud/pagination"

// We have the option of filtering objects by their attributes
opts := &objects.ListOpts{Full: true}

// Retrieve a pager (i.e. a paginated collection)
pager := objects.List(client, "container_name", opts)

// Define an anonymous function to be executed on each page's iteration
err := pager.EachPage(func(page pagination.Page) (bool, error) {

    // Get a slice of objects.Object structs
    objectList, err := objects.ExtractInfo(page)
    for _, n := range objectNames {
        // ...
    }

    // Get a slice of strings, i.e. object names
    objectNames, err := containers.ExtractNames(page)
    for _, n := range objectNames {
        // ...
    }

    return true, nil
})

Problem 1

    ...
    // Get a slice of objects.Object structs
    objectList, err := objects.ExtractInfo(page)
    for _, n := range objectNames {
        // ...
    }
    ...

This for loop is trying to loop over a variable that doesn't exist (it is declared a couple of lines further down). To me, this just looks like a mistaken copy&paste.

Solution

Changing for _, n := range objectNames { to for _, o := range objectList { fixes this piece of the example.

Problem 2

    ...
    // Get a slice of strings, i.e. object names
    objectNames, err := containers.ExtractNames(page)
    for _, n := range objectNames {
        // ...
    }
    ...

Running this results in the following error:

panic: interface conversion: pagination.Page is objects.ObjectPage, not containers.ContainerPage [recovered] panic: interface conversion: pagination.Page is objects.ObjectPage, not containers.ContainerPage

Solution

So instead of using containers.ExtractNames(page), using objects.ExtractNames(page) fixes this piece of the example.

Summary

I'd recommend changing that example to...

import "github.com/rackspace/gophercloud/pagination"

// We have the option of filtering objects by their attributes
opts := &objects.ListOpts{Full: true}

// Retrieve a pager (i.e. a paginated collection)
pager := objects.List(client, "container_name", opts)

// Define an anonymous function to be executed on each page's iteration
err := pager.EachPage(func(page pagination.Page) (bool, error) {

    // Get a slice of objects.Object structs
    objectList, err := objects.ExtractInfo(page)
    for _, o := range objectList {
        // ...
    }

    // Get a slice of strings, i.e. object names
    objectNames, err := objects.ExtractNames(page)
    for _, n := range objectNames {
        // ...
    }

    return true, nil
})

rackspace / gophercloud