如何在LINQ中的select中添加where子句？

Question

我有以下幾點：

var result =
    from entry in feed.Descendants(a + "entry")
    let content = entry.Element(a + "content")
    let properties = content.Element(m + "properties")
    let text = properties.Element(d + "Text")
    let title = properties.Element(d + "Title")
    let partitionKey = properties.Element(d + "PartitionKey")
    select new Content
    {
        Text = text.Value,
        Title = title.Value
    };

我想做的是添加一個位置，以便僅將某些項目放入結果中。 如何添加條件：

partitionKey.Substring(2, 2) == "03" && text != null

選擇？

Answer 1

只需在選擇之前添加條件：

var result =
    from entry in feed.Descendants(a + "entry")
    let content = entry.Element(a + "content")
    let properties = content.Element(m + "properties")
    let text = properties.Element(d + "Text")
    let title = properties.Element(d + "Title")
    let partitionKey = properties.Element(d + "PartitionKey")
    where partitionKey.Value.Substring(2, 2) == "03"
    where text != null
    select new Content
    {
        Text = text.Value,
        Title = title.Value
    };

Answer 2

代替

where partitionKey.Substring(2, 2) == "03" && text != null

采用

where partitionKey.Value.Substring(2, 2) == "03" && text != null

當需要它的值時，partitionKey的類型為XElement。

Answer 3

在select之前指定where ：

var result =
    from entry in feed.Descendants(a + "entry")
    let content = entry.Element(a + "content")
    let properties = content.Element(m + "properties")
    let text = properties.Element(d + "Text")
    let title = properties.Element(d + "Title")
    let partitionKey = properties.Element(d + "PartitionKey")
    where partitionKey.Substring(2, 2) == "03" && text != null
    select new Content
    {
        Text = text.Value,
        Title = title.Value
    };

Answer 4

        var result =
from entry in feed.Descendants(a + "entry")
let content = entry.Element(a + "content")
let properties = content.Element(m + "properties")
let text = properties.Element(d + "Text")
let title = properties.Element(d + "Title")
let partitionKey = properties.Element(d + "PartitionKey")
where partitionKey.Value.Substring(2, 2) == "03" && text != null
select new Content
{
    Text = text.Value,
    Title = title.Value
};

Answer 5

我建議使用將SQL腳本轉換為LINQ的linquer軟件，在一次內部聯接和更多complecx查詢時想象一下嗎？

訪問： www.sqltolinq.com/

這是非常方便的工具！