字符串到LINQ表达式? [英] String to LINQ expression?

问题描述

如何将带有查询的字符串转换为实际的LINQ表达式，以便执行它?

How can I transform the string with the query in it into an actual LINQ expression so I can execute it?

if(email!= null)
{
    query += "x => x.Email.Contains(email)";
}
if (firstname != null)
{
    query += "&& x.FirstName.Contains(firstname)";
}
if (lastname != null)
{
    query += "&& x.LastName.Contains(lastname)";
}
return context.UserAccounts.Where(query).ToList();

推荐答案

尝试一下:

<your collection>.
    .Where(o => (email!= null)? o.Email.Contains(email) : true).
    .Where(o => (firstname != null)? o.FirstName.Contains(firstname) : true).
    .Where(o => (lastname != null)? o.LastName.Contains(lastname) : true).
    ToList();

基本上，这意味着过滤器仅在满足条件时才适用(就像if语句中一样).

Basically it means the filter will apply only when the condition is met (just like in your if sentences).

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