Documentation | Getting Started
Source generator that enables modern C# syntax in LINQ expression trees. All expression trees are generated at compile time with minimal runtime overhead.
There are two problems when using C# with LINQ providers like EF Core:
1. Expression tree syntax restrictions. You write a perfectly reasonable query and hit:
error CS8072: An expression tree lambda may not contain a null propagating operator
Expression trees (Expression<Func<...>>) only support a restricted subset of C# — no ?., no switch expressions, no pattern matching. So you end up writing ugly ternary chains instead of the clean code you'd write anywhere else. (Why hasn't this been fixed?)
2. Computed properties are opaque to LINQ providers. You define public string FullName => $"{FirstName} {LastName}" and use it in a query — but EF Core can't see inside the property getter. It either throws a runtime translation error, or worse, silently fetches the entire entity to evaluate FullName on the client (overfetching). The only workaround is to duplicate the logic as an inline expression in every query that needs it.
ExpressiveSharp fixes this. Write natural C# and the source generator builds the expression tree at compile time:
publicclassOrder{publicintId{get;set;}publicdoublePrice{get;set;}publicintQuantity{get;set;}publicCustomer?Customer{get;set;}// Computed property — reusable in any query, translated to SQL[Expressive]publicdoubleTotal=>Price*Quantity;// Switch expression — normally illegal in expression trees[Expressive]publicstringGetGrade()=>Priceswitch{>=100=>"Premium",>=50=>"Standard",
_ =>"Budget",};}// [Expressive] members + ?. syntax — all translated to SQLvarresults=db.Orders.AsExpressiveDbSet().Where(o =>o.Customer?.Email!=null).Select(o =>new{o.Id,o.Total,Email=o.Customer?.Email,Grade=o.GetGrade()}).ToList();Generated SQL (SQLite — other providers produce equivalent dialect-specific SQL):
SELECT"o"."Id",
"o"."Price"* CAST("o"."Quantity"ASREAL) AS"Total",
"c"."Email",
CASE
WHEN "o"."Price">=100.0 THEN 'Premium'
WHEN "o"."Price">=50.0 THEN 'Standard'
ELSE 'Budget'
END AS"Grade"FROM"Orders"AS"o"LEFT JOIN"Customers"AS"c"ON"o"."CustomerId"="c"."Id"WHERE"c"."Email"IS NOT NULLdotnet add package ExpressiveSharp
# Lightweight alternative (attributes + source generator only, no runtime services):# dotnet add package ExpressiveSharp.Abstractions# Optional: EF Core integration
dotnet add package ExpressiveSharp.EntityFrameworkCoreSee the BasicSample and EFCoreSample projects for runnable examples.
Mark computed properties and methods with [Expressive] to generate companion expression trees. Then choose how to wire them into your queries:
| Scenario | API |
|---|---|
EF Core — modern syntax + [Expressive] expansion on DbSet | ExpressiveDbSet<T> |
Any IQueryable — modern syntax + [Expressive] expansion | .AsExpressive() |
| EF Core — SQL window functions (ROW_NUMBER, RANK, etc.) | WindowFunction.* |
Advanced — build an Expression<T> inline, no attribute needed | ExpressionPolyfill.Create |
Advanced — expand [Expressive] members in an existing expression tree | .ExpandExpressives() |
| Advanced — make third-party/BCL members expressable | [ExpressiveFor] |
| Category | Examples |
|---|---|
| Null-conditional operators | ?. member access and indexer |
| Switch expressions | With relational, logical, type, and property patterns |
| Pattern matching | Constant, type, relational, logical, property, positional, list patterns |
| String interpolation | Converted to string.Concat |
| Constructor projections | [Expressive] constructors for DTO projections with inheritance support |
| Block bodies (opt-in) | if/else, switch statements, foreach/for loops, local variables |
| External member mapping | [ExpressiveFor] for BCL/third-party members |
Tuples, index/range, with, collection expressions | And more modern C# syntax |
| Expression transformers | Built-in + custom IExpressionTreeTransformer pipeline |
| SQL window functions | ROW_NUMBER, RANK, DENSE_RANK, NTILE, PERCENT_RANK, CUME_DIST, SUM/AVG/COUNT/MIN/MAX OVER, LAG/LEAD, FIRST_VALUE/LAST_VALUE/NTH_VALUE with ROWS/RANGE frames |
| Hot reload | Compatible with dotnet watch — edits to [Expressive] bodies propagate to generated expression trees |
See the full documentation for detailed usage, reference, and recipes.
dotnet build # Build all projects
dotnet test# Run all tests- Testing Strategy — snapshot tests, functional tests, and test consumers
- How It Works — source generator internals
MIT