SQL LINQ评估逗号分隔的字符串包含值

如何解决SQL LINQ评估逗号分隔的字符串包含值

我正在使用EFCore Linq并遇到问题。我有一个存储逗号分隔的字符串的表，我需要在where子句中使用它来仅过滤包含某些值的字符串。这是我的Linq：

var volunteers = context.Volunteers
               .Where(x => x.StatusId == 1
                     && x.RoleIds.Split(',',StringSplitOptions.None).Contains("1")
                ).ToList();

该列是RoleIds。我收到的错误是Linq查询无法翻译。我在这里需要做什么？谢谢！

解决方法

如果可以使用LINQKit（或滚动自己的重点版本），则可以创建扩展来为您处理测试：

public static class IQueryableExt { // using LINQKit
    // string fieldExpr(T row) - function returning multiple value string field to test
    // delimiter - string separator between values in test field
    // value - string value to find in values of test field
    // dbq.Where(r => fieldExpr(r).Split(delimiter).Contains(value))
    public static IQueryable<T> WhereSplitContains<T>(this IQueryable<T> dbq,Expression<Func<T,string>> fieldExpr,string delimiter,string value) {
        var pred = PredicateBuilder.New<T>(r => fieldExpr.Invoke(r) == value);
        pred = pred.Or(r => fieldExpr.Invoke(r).StartsWith(value + delimiter));
        pred = pred.Or(r => fieldExpr.Invoke(r).EndsWith(delimiter + value));
        pred = pred.Or(r => fieldExpr.Invoke(r).Contains(delimiter + value + delimiter));

        return dbq.Where((Expression<Func<T,bool>>)pred.Expand());
    }

    // values - string values,one of which to find in values of test field
    // string fieldExpr(T row) - function returning multiple value string field to test
    // delimiter - string separator between values in test field
    // dbq.Where(r => values.Any(value => fieldExpr(r).Split(delimiter).Contains(value)))
    public static IQueryable<T> WhereAnySplitContains<T>(this IQueryable<T> dbq,IEnumerable<string> values,string delimiter) {
        var pred = PredicateBuilder.New<T>();
        foreach (var value in values) {
            pred = pred.Or(r => fieldExpr.Invoke(r) == value);
            pred = pred.Or(r => fieldExpr.Invoke(r).StartsWith(value + delimiter));
            pred = pred.Or(r => fieldExpr.Invoke(r).EndsWith(delimiter + value));
            pred = pred.Or(r => fieldExpr.Invoke(r).Contains(delimiter + value + delimiter));
        }

        return dbq.Where((Expression<Func<T,bool>>)pred.Expand());
    }
    public static IQueryable<T> WhereSplitContainsAny<T>(this IQueryable<T> dbq,IEnumerable<string> values) =>
        dbq.WhereAnySplitContains(values,fieldExpr,delimiter);
    public static IQueryable<T> WhereSplitContainsAny<T>(this IQueryable<T> dbq,params string[] values) =>
        dbq.WhereAnySplitContains(values,delimiter);

    // values - string values,all of which to find in values of test field
    // string fieldExpr(T row) - function returning multiple value string field to test
    // delimiter - string separator between values in test field
    // dbq.Where(r => values.All(value => fieldExpr(r).Split(delimiter).Contains(value)))
    public static IQueryable<T> WhereAllSplitContains<T>(this IQueryable<T> dbq,string delimiter) {
        var pred = PredicateBuilder.New<T>();
        foreach (var value in values) {
            var subPred = PredicateBuilder.New<T>(r => fieldExpr.Invoke(r) == value);
            subPred = subPred.Or(r => fieldExpr.Invoke(r).StartsWith(value + delimiter));
            subPred = subPred.Or(r => fieldExpr.Invoke(r).EndsWith(delimiter + value));
            subPred = subPred.Or(r => fieldExpr.Invoke(r).Contains(delimiter + value + delimiter));
            pred = pred.And(subPred);
        }

        return dbq.Where((Expression<Func<T,bool>>)pred.Expand());
    }
    public static IQueryable<T> WhereSplitContainsAll<T>(this IQueryable<T> dbq,IEnumerable<string> values) =>
        dbq.WhereAllSplitContains(values,delimiter);
    public static IQueryable<T> WhereSplitContainsAll<T>(this IQueryable<T> dbq,params string[] values) =>
        dbq.WhereAllSplitContains(values,delimiter);
}

使用这些扩展名，您的查询将是：

var volunteers = context.Volunteers.Where(x => x.StatusId == 1)
                                   .WhereSplitContains(r => r.RoleIds,","1")
                                   .ToList();

如果您有多个值，则可以使用其他变体：

var volunteers = context.Volunteers.Where(x => x.StatusId == 1)
                                   .WhereSplitContainsAny(r => r.RoleIds,"1","2")
                                   .ToList();