--- title: "JSON Tricks: Extending an Embedded Marshaler" url: https://daily.dev/posts/json-tricks-extending-an-embedded-marshaler-akawfzbii source_url: https://boldlygo.tech/posts/2020-06-26-go-json-tricks-embedded-marshaler type: article source: "Boldly Go" published: 2026-05-31T07:50:11.266Z updated: 2026-05-31T09:09:42.327Z tags: ["golang"] reading_time: 5 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # JSON Tricks: Extending an Embedded Marshaler **[Boldly Go](https://daily.dev/sources/boldlygo)** · 5 min read · 0 upvotes · 0 comments ## Summary When embedding a struct with a custom MarshalJSON method in Go, the promoted method causes any additional fields on the outer struct to be silently ignored during marshaling. The solution is to define a new MarshalJSON on the outer type that explicitly calls the embedded type's MarshalJSON, marshals only the new fields into a separate JSON object using a local type, then splices the two JSON byte slices together by replacing the opening brace of the second with a comma and appending it to the first (minus its closing brace). This avoids duplicating the embedded type's logic while correctly including all fields in the output. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Lazy attribute evaluation for JSONHandler](https://daily.dev/posts/lazy-attribute-evaluation-for-jsonhandler-qc9mwy8bm) · Boldly Go · 15 upvotes · 0 comments - [A new experimental Go API for JSON](https://daily.dev/posts/a-new-experimental-go-api-for-json-u5mtnrdxh) · Go · 34 upvotes · 0 comments --- Tags: [#golang](https://daily.dev/tags/golang) [View this post on daily.dev](https://daily.dev/posts/json-tricks-extending-an-embedded-marshaler-akawfzbii)