我如何编写一个将 LINQ 转换为 SQL 的 ORM？
我已经创建了一个现有的 ORM，但我想用 LINQ 改进它，这样我就可以说：
MyORMObject.GetAll(o => o.firstName == "peter");
我脑子里的想法是系统将把它转换成查询。我想最困难的部分是读取解析到 LINQ 部分的内容。
我该怎么做？换句话说，我将如何（通过反射或其他方式）读取正在使用的 FirstName 属性及其所需的匹配项“Peter”？
How could I write an ORM that would convert LINQ into SQL?
I already have made an existing ORM, but I want to improve it with LINQ, so that I, for instance would be able to say:
MyORMObject.GetAll(o => o.firstName == "peter");
The idea in my head is that the system would then take that and convert it into a query. I guess the hard part is to read the stuff parsed into the LINQ part.
How do I do this? In other words, how would I (through Reflection or something else) read the FirstName property being used, and its desired match, "Peter"?
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您将需要实现 IQueryable LINQ提供者。顺便说一下，您不会使用反射，您将使用 表达式树。
You are going to need to implement an IQueryable LINQ Provider. You won't be using reflection by the way, you'll be using Expression trees.
如果您的方法是
IEnumerable; GetAll(Expression>) ，则 lambda 表达式将被编译为表达式树，并带有Equals子表达式，该子表达式又有一个包含FirstName属性的MemberExpression和一个包含字符串的ConstantExpression。If your method is
IEnumerable<T> GetAll<T>(Expression<Func<T,bool>>), then the lambda expression will be compiled as an expression tree, with anEqualssub-expression, which in turn has aMemberExpressioncontaining theFirstNameproperty, and aConstantExpressioncontaining the string.