[英]How to build dynamic queries for MongoDB in c# using both & and | operators
所以我有一個鍵值對列表,鍵是一個字符串,值是一個字符串數組,如下所示:
{
"filters": [
{"key": "team", "value": ["3","4","7"]},
{"key": "placement_type", "value": ["facility"]}
//{"key": "date", "value": ["2021-01-01"]}
//{"key": "policy", "value": ["something"]} Number of filters may vary
]
}
這個“過濾器”列表可以有多個鍵值對,具體取決於用戶選擇的過濾器數量。
所以我需要動態創建的是以下查詢:
(builder.Eq("team", "3") | builder.Eq("team", "4") | builder.Eq("team", "7")) & builder.Eq("placement_type", "Facility");
這是我的嘗試:
var builder = Builders<ReportDocument>.Filter;
// IF I USE THIS QUERY IT WORKS AS I EXPECT
var hardCodedQuery = (builder.Eq("team", "3") | builder.Eq("team", "4") | builder.Eq("team", "7")) & builder.Eq("placement_type", "Facility");
var dynamicQuery = builder.Empty;
var orFilters = builder.Empty;
foreach (var filter in request.Filters)
{
if (filter.Value.Length > 1)
{
for (int i = 0; i < filter.Value.Length; i++)
{
if (i == 0)
{
orFilters = builder.Eq(filter.Key, filter.Value[i]); //Had to do this since i have to initiate the variable as builder.Empty and it was adding and EmptyFilterDefinition
}
else
{
orFilters &= builder.Eq(filter.Key, filter.Value[i]);
}
}
dynamicQuery = builder.Or(orFilters);
}
else
{
dynamicQuery &= builder.Eq(filter.Key, filter.Value);
}
}
return await _reportsCollection.Find(dynamicQuery).ToListAsync();
但是一旦我在變量“orFilters”中插入第二個過濾器,運算符“&= e 就變成了 MongoDB.Driver。 AndFilterDefinition而不是 MongoDB.Driver。 或過濾器定義
因此,如果有人有這樣做的好方法,請分享給大家。 我在 stackoverflow 中看到了很多與我的問題類似的問題,但所有參考都只使用 & (And) 運算符做動態過濾器。 但是因為我有一個字符串列表作為值,所以我需要使用 | (或)運算符也是如此。
謝謝
您的第一個復合分配與您的預期查詢不匹配,在您的示例中您使用OR
但在您的代碼中您使用的是AND
分配
....
if (filter.Value.Length > 1)
{
for (int i = 0; i < filter.Value.Length; i++)
{
if (i == 0)
{
orFilters = builder.Eq(filter.Key, filter.Value[i]); //Had to do this since i have to initiate the variable as builder.Empty and it was adding and EmptyFilterDefinition
}
else
{
// this line was changed
orFilters |= builder.Eq(filter.Key, filter.Value[i]);
}
}
//also when this line run, you are resetting your filter so pay attention to it, should change
dynamicQuery = builder.Or(orFilters);
}
.....
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