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Type:
Improvement
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Linq
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Labels:None
Syntax
{$indexOfBytes: [<string>, <search value>, <start index - optional>, <end index - optional>]}
{$indexOfCP: [<string>, <search value>, <start index - optional>, <end index - optional>]}
{$indexOfArray: [<array>, <search value>, <start index - optional>, <end index - optional>]}
Examples
> db.coll.insert([
{_id: 1, string: "hello world"}
]);
> db.coll.aggregate([{
$project: {
location: {$indexOfBytes: ["$string", "world"]}
}
}]);
{_id: 1, location: 6}
// Example 2 - differentiating code points vs. bytes.
> db.coll.insert([
{_id: 1, string: "øle"}
]);
> db.coll.aggregate([{
$project: {
byteLocation: {$indexOfBytes: ["$string", "le"]},
cpLocation: {$indexOfCP: ["$string", "le"]}
}
}]);
{_id: 1, byteLocation: 2, cpLocation: 1}
// Example 3 - using the start index.
> db.coll.insert([
{_id: 1, string: "PREFIX|text with word FIX"}, // Contains "FIX", Should match.
{_id: 2, string: "PREFIX|text without target"} // Should not match.
]);
> db.coll.aggregate([{
$project: {
containsFix: {$indexOfCP: ["$string", "fix", {$strLenCP: "PREFIX|"}]}
}
}]);
{_id: 1, containsFix: 22}
{_id: 2, containsFix: -1}
// Example 4 - using the start and end indices.
> db.coll.insert([
{_id: 1, string: "PREFIX|text with word FIX|SUFFIX"}, // Contains "FIX", Should match.
{_id: 2, string: "PREFIX|text without target|SUFFIX"} // Should not match.
]);
> db.coll.aggregate([{
$project: {
containsFix: {
$let: {
vars: {
startIndex: {$strLenCP: "PREFIX|"}, // 7
endIndex: {$subtract: [0, {$strLenCP: "|SUFFIX"}]} // -7
},
in: {$indexOfCP: ["$string", "fix", "$$startIndex", "$$endIndex"]}
}
}
}
}]);
{_id: 1, containsFix: 22}
{_id: 2, containsFix: -1}
Notes
- Same functionality as Python's find(). Returns -1 if there were no occurrences.
Errors
- For indexOfBytes/indexOfCP, if the first two arguments are not strings. For indexOfArray, if the first argument is not an array.
- If either of the last two arguments are not integral.
Old Description
Would like to have some operator to find character (or substring) in string. Use case - normalizing strings like server names "server1.foo.bar" to short names via $substr operator (without knowing location of first '.')
- depends on
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- Closed
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