Pulling a value from a string array using mongodb c#, if it contains substring

Question

I want to remove a string from array of strings of a mongodb model, if the string contains substring value

The model is like this

{
    "username": "my_user",
    "str_array": [
        "remove_substring_found/rest_of_string",
        "this_string_wont_be_removed"
    ]
}

Here is what I tried so far, but it is not working

string compare_str = "remove_substring_found";
var filter = Builders<MyModel>.Filter.Eq(s => s.username, "my_user");
var regex = new BsonRegularExpression(string.Format(".*{0}.*", compare_str ), "i");
var filter_update = Builders<string>.Filter.Regex(x => x, regex);
var update = Builders<MyModel>.Update.PullFilter(x => x.str_array, filter_update);
var result = await MyCollection.UpdateOneAsync(filter, update);

Dĵ ΝιΓΞΗΛψΚ · Accepted Answer · 2021-07-30 16:37:41Z

2

afaik the PullFilter only supports complex objects. it doesn't seem to be working for primitive types such as strings. you're supposed to use the Pull update operator instead for primitives. but the issue with Pull in c# is that it doesn't seem to support regex in a strongly-typed manner. so you need to construct an update definition manually like the following:

var userFilter = Builders<MyModel>.Filter.Where(i => i.username == "my_user");

UpdateDefinition<MyModel> update = "{ '$pull': { 'str_array': /substring_found/ } }";

await collection.UpdateManyAsync(userFilter, update);

edited Jul 30, 2021 at 16:37

answered Jul 30, 2021 at 14:29

Dĵ ΝιΓΞΗΛψΚ

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