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POGet records before and after current selection in Django query
 

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    <p>It sounds like an odd one but it's a really simple idea. I'm trying to make a simple Flickr for a website I'm building. This specific problem comes when I want to show a single photo (from my <code>Photo</code> model) on the page but I also want to show the image before it in the stream and the image after it.</p> <p>If I were only sorting these streams by date, or was only sorting by ID, that might be simpler... But I'm not. I want to allow the user to sort and filter by a whole variety of methods. The sorting is simple. I've done that and I have a result-set, containing 0-many <code>Photo</code>s.</p> <p>If I want a single <code>Photo</code>, I start off with that filtered/sorted/etc stream. From it I need to get the current <code>Photo</code>, the <code>Photo</code> before it and the <code>Photo</code> after it.</p> <p>Here's what I'm looking at, at the moment.</p> <pre><code>prev = None next = None photo = None for i in range(1, filtered_queryset.count()): if filtered_queryset[i].pk = desired_pk: if i&gt;1: prev = filtered_queryset[i-1] if i&lt;filtered_queryset.count(): next = filtered_queryset[i+1] photo = filtered_queryset[i] break </code></pre> <p>It just seems disgustingly messy. And inefficient. Oh my lord, so inefficient. Can anybody improve on it though?</p> <p>Django queries are late-binding, so it would be nice to make use of that though I guess that might be impossible given my horrible restrictions.</p> <p>Edit: it occurs to me that I can just chuck in some SQL to re-filter queryset. If there's a way of selecting something with its two (or one, or zero) closest neighbours with SQL, I'd love to know!</p>
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      1. USJoel L
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    1. COSeems like you're trying to create indices where you have none. If you had a group of people and picked one out of the crowd and said, "Find me the next tallest and next shortest person relative to this person," how else would you do it?
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      1. USa paid nerd
    2. CO"Then, and only then, can I see if my image is in that selection" <- Could you explain why that is the case? Don't you have the image ID in the url?
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      1. USEmil Stenström
    3. CO@Emil I have the pk of the wanted image but I need to locate it in the list (which involves ticking through it if above is the only option). I can't just filter again (or `.get()`) because that would stop me getting prev/next Photos
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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