array.deleteAt(offset [,endOffset]) → array
Remove one or more elements from an array at a given index. Returns the modified array. (Note: deleteAt operates on arrays, not documents; to delete documents, see the delete command.)
If only offset is specified, deleteAt removes the element at that index. If both offset and endOffset are specified, deleteAt removes the range of elements between offset and endOffset, inclusive of offset but not inclusive of endOffset.
If endOffset is specified, it must not be less than offset. Both offset and endOffset must be within the array’s bounds (i.e., if the array has 10 elements, an offset or endOffset of 10 or higher is invalid).
By using a negative offset you can delete from the end of the array. -1 is the last element in the array, -2 is the second-to-last element, and so on. You may specify a negative endOffset, although just as with a positive value, this will not be inclusive. The range (2,-1) specifies the third element through the next-to-last element.
Example: Delete the second element of an array.
r.expr(r.array("a", "b", "c", "d", "e", "f")).deleteAt(1).run(conn);
// Result:
["a", "c", "d", "e", "f"]
Example: Delete the second and third elements of an array.
r.expr(r.array("a", "b", "c", "d", "e", "f")).deleteAt(1, 3).run(conn);
// Result:
["a", "d", "e", "f"]
Example: Delete the next-to-last element of an array.
r.expr(r.array("a", "b", "c", "d", "e", "f")).deleteAt(-2).run(conn);
// Result:
["a", "b", "c", "d", "f"]
Example: Delete a comment on a post.
Given a post document such as:
{
"id": "4cf47834-b6f9-438f-9dec-74087e84eb63",
"title": "Post title",
"author": "Bob",
"comments": [
{ "author": "Agatha", "text": "Comment 1" },
{ "author": "Fred", "text": "Comment 2" }
]
}
The second comment can be deleted by using update and deleteAt together.
r.table("posts").get("4cf47834-b6f9-438f-9dec-74087e84eb63").update(
row -> r.hashMap("comments", row.g("comments").deleteAt(1)
).run(conn);
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https://rethinkdb.com/api/java/delete_at/