如何从IQueryable中提取where子句表达式树

using System;
using System.Linq;
using System.Linq.Expressions;

public class WhereClauseExtractor : ExpressionVisitor
{
    private Expression whereClause;

    public Expression ExtractWhereClause(IQueryable queryable)
    {
        Visit(queryable.Expression);
        return whereClause;
    }

    protected override Expression VisitMethodCall(MethodCallExpression node)
    {
        if (node.Method.Name == "Where")
        {
            var lambdaExpression = (LambdaExpression)((UnaryExpression)node.Arguments[1]).Operand;
            whereClause = lambdaExpression.Body;
        }

        return base.VisitMethodCall(node);
    }
}

// 使用示例
var queryable = dbContext.Entities.Where(e => e.Property == value);
var extractor = new WhereClauseExtractor();
var whereClause = extractor.ExtractWhereClause(queryable);