From 99895c7b2e968040ff7d5057ec2cb402ed5c4662 Mon Sep 17 00:00:00 2001
From: Jacob Quinn <jacob.quinn@cbtravel.com>
Date: Thu, 16 Oct 2025 18:05:03 -0600
Subject: [PATCH] Restore pre-1.0 compat for object Tuple keys

---
 src/write.jl | 3 +++
 test/json.jl | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/src/write.jl b/src/write.jl
index 7a5c9c1..775ab49 100644
--- a/src/write.jl
+++ b/src/write.jl
@@ -16,6 +16,9 @@ StructUtils.lower(::JSONStyle, x::AbstractArray{<:Any,0}) = x[1]
 StructUtils.lower(::JSONStyle, x::AbstractArray{<:Any, N}) where {N} = (view(x, ntuple(_ -> :, N - 1)..., j) for j in axes(x, N))
 StructUtils.lower(::JSONStyle, x::AbstractVector) = x
 
+# for pre-1.0 compat, which serialized Tuple object keys by default
+StructUtils.lowerkey(::JSONStyle, x::Tuple) = string(x)
+
 """
     JSON.omit_null(::Type{T})::Bool
     JSON.omit_null(::JSONStyle, ::Type{T})::Bool
diff --git a/test/json.jl b/test/json.jl
index 2564ff8..4af4b64 100644
--- a/test/json.jl
+++ b/test/json.jl
@@ -588,6 +588,10 @@ end
             @test result == expected
         end
     end
+
+    @testset "Test pre-1.0 compat for object Tuple keys" begin
+        @test JSON.json(Dict(("a", "b") => 1)) == "{\"(\\\"a\\\", \\\"b\\\")\":1}"
+    end
 end
 
 end # @testset "JSON.json"