


How to sort the product list and support spreading operations by dragging?
Apr 02, 2025 pm 01:12 PMDrag and drop ordering and spread page operation on e-commerce platform product list
Many e-commerce applications need to support users to drag and drop to adjust the order of product lists and allow spread-page operations. This article introduces an efficient sorting algorithm that implements this function while minimizing changes to existing systems (such as product addition and modification operations). The database already has a sort
field (the initial value is 0), and the product list is currently displayed in reverse order of time.
Sorting algorithm design
We use a sort
field-based algorithm. During initial sorting, you need to assign a value to sort
field of each item and reserve a sufficient gap, such as 1000. The following SQL statements implement initial sorting:
SET @sort := 0; UPDATE product SET sort = (@sort := @sort 1000) ORDER BY id;
This will cause sort
value to start at 1000, incrementing by 1000 each time. For example:
id | sort |
---|---|
1 | 1000 |
2 | 2000 |
3 | 3000 |
When the user drags the product, the new sort
value is recalculated. Suppose that the item with id 3 is dragged between id 1 and id 2, and the new sort
value is the intermediate value of the two sort
values ??before and after:
New sort
value = 1000 (2000 - 1000) / 2 = 1500
Update the sort
value of the product with id 3:
id | sort |
---|---|
1 | 1000 |
3 | 1500 |
2 | 2000 |
To improve flexibility, random numbers can be added when calculating intermediate values ??to avoid too uniform sort
values.
When sort
value gap is not enough to support finer sorting, readjust sort
value and expand the gap:
SET @sort := 0; UPDATE product SET sort = (@sort := @sort 1000) ORDER BY sort;
This algorithm ensures that the sorting function is continuously efficient and has minimal impact on existing systems. The spread page operation only needs to correctly obtain sort
value of the target position during the drag and drop process, and the algorithm itself does not need to be modified.
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