feature/add-custom-validation-error (OxygenFramework#214)

* added custom validation error handling
* cleaned up the string interpolation in the server welcome function

src/core.jl

@@ -12,6 +12,7 @@ using RelocatableFolders
 using DataStructures: CircularDeque
 import Base.Threads: lock, nthreads
 
+include("errors.jl");       @reexport using .Errors
 include("util.jl");         @reexport using .Util
 include("types.jl");        @reexport using .Types 
 include("constants.jl");    @reexport using .Constants
@@ -44,10 +45,10 @@ function serverwelcome(external_url::String, docs::Bool, metrics::Bool, parallel
     @info "📦 Version 1.5.12 (2024-06-18)"
     @info "✅ Started server: $external_url"
     if docs
-        @info "📖 Documentation: $external_url$docspath"
+        @info "📖 Documentation: $external_url" * docspath
     end
     if docs && metrics
-        @info "📊 Metrics: $external_url$docspath/metrics"
+        @info "📊 Metrics: $external_url" * "$docspath/metrics"
     end
     if parallel
         @info "🚀 Running in parallel mode with $(Threads.nthreads()) threads"

src/errors.jl

@@ -0,0 +1,15 @@
+module Errors
+## In this module, we export commonly used exceptions across the package 
+
+export ValidationError
+
+# This is used by the Extractors.jl module to signal that a validation error has occurred
+struct ValidationError <: Exception
+    msg::String
+end
+
+function Base.showerror(io::IO, e::ValidationError)
+    print(io, "Validation Error: $(e.msg)")
+end
+
+end

src/extractors.jl

@@ -8,6 +8,7 @@ using StructTypes
 
 using ..Util: text, json, formdata, parseparam
 using ..Reflection: struct_builder, extract_struct_info
+using ..Errors: ValidationError
 using ..Types
 
 export Extractor, extract, validate, extracttype, isextractor, isreqparam, isbodyparam,
@@ -85,14 +86,14 @@ function try_validate(param::Param{U}, instance::T) :: T where {T, U <: Extracto
     # Case 1: Use global validate function - returns true if one isn't defined for this type
     if !validate(instance)
         impl = Base.which(validate, (T,))
-        throw(ArgumentError("Validation failed for $(param.name): $T \n|> $instance \n|> $impl"))   
+        throw(ValidationError("Validation failed for $(param.name): $T \n|> $instance \n|> $impl"))   
     end
 
     # Case 2: Use custom validate function from an Extractor (if defined)
     if param.hasdefault && param.default isa U && !isnothing(param.default.validate)
         if !param.default.validate(instance)
             impl = Base.which(param.default.validate, (T,))
-            throw(ArgumentError("Validation failed for $(param.name): $T \n|> $instance \n|> $impl"))
+            throw(ValidationError("Validation failed for $(param.name): $T \n|> $instance \n|> $impl"))
         end
     end
 

src/utilities/misc.jl

@@ -2,11 +2,12 @@ using HTTP
 using JSON3
 using Dates
 
+using ..Errors: ValidationError
+
 export countargs, recursive_merge, parseparam, 
     queryparams, redirect, handlerequest,
     format_response!, set_content_size!, format_sse_message
 
-
 ### Request helper functions ###
 
 """
@@ -19,7 +20,6 @@ function queryparams(req::HTTP.Request) :: Dict
     return HTTP.queryparams(uri.query)
 end
 
-
 """
     redirect(path::String; code = 308)
 
@@ -29,6 +29,14 @@ function redirect(path::String; code = 307) :: HTTP.Response
     return HTTP.Response(code, ["Location" => path])
 end
 
+function handle_error(::ValidationError)
+    return json(("message" => "400: Bad Request"), status = 400)    
+end
+
+function handle_error(::Any)
+    return json(("message" => "500: Internal Server Error"), status = 500)    
+end
+
 function handlerequest(getresponse::Function, catch_errors::Bool; show_errors::Bool = true)
     if !catch_errors
         return getresponse()
@@ -37,9 +45,9 @@ function handlerequest(getresponse::Function, catch_errors::Bool; show_errors::B
             return getresponse()       
         catch error
             if show_errors && !isa(error, InterruptException)
-                 @error "ERROR: " exception=(error, catch_backtrace())
+                @error "ERROR: " exception=(error, catch_backtrace())
             end
-            return json(("message" => "The Server encountered a problem"), status = 500)    
+            return handle_error(error)
         end  
     end
 end

test/extractortests.jl

@@ -90,14 +90,14 @@ end
     # Test that negative age trips the global validator
     req = HTTP.Request("GET", "/", [], """name=joe&age=-4""")
     param = Param(:form, Form{Person}, missing, false)
-    @test_throws ArgumentError extract(param, LazyRequest(request=req))
+    @test_throws Oxygen.Core.Errors.ValidationError extract(param, LazyRequest(request=req))
 
 
     # Test that age < 25 trips the local validator
     req = HTTP.Request("GET", "/", [], """name=joe&age=10""")
     default_value = Form{Person}(x -> x.age > 25)
     param = Param(:form, Form{Person}, default_value, true)
-    @test_throws ArgumentError extract(param, LazyRequest(request=req))
+    @test_throws Oxygen.Core.Errors.ValidationError extract(param, LazyRequest(request=req))
 end
 
 
@@ -253,7 +253,7 @@ end
     @suppress_err begin 
         # should fail since we are missing query params
         r = internalrequest(HTTP.Request("GET", "/headers", ["limit" => "3"], ""))
-        @test r.status == 500
+        @test r.status == 400
     end
 
     @suppress_err begin 
@@ -265,7 +265,7 @@ end
             "value": 12.0
         }
         """))
-        @test r.status == 500
+        @test r.status == 400
     end
 
     r = internalrequest(HTTP.Request("POST", "/json", [], """