feat: allow custom json encoder/decoder.

jmcarp · jmcarp · commit 1e55295f807c · 2025-11-14T11:43:22.000-05:00
The encoding/json package in the standard library isn't particularly
performant, and there have been many first-party and third-party efforts to
improve it. This patch allows users of the sdk to configure a custom json codec
to marshall and unmarshall json with their tools of choice. Note: we can update
to encoding/json/v2 as the default once it's marked stable in a future golang
release.
diff --git a/internal/generate/templates/no_resptype_body_method.tpl b/internal/generate/templates/no_resptype_body_method.tpl
@@ -4,7 +4,7 @@
 	}{{end}}{{if .IsAppJSON}}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return fmt.Errorf("encoding json body request failed: %v", err)
     }{{else}}
     b := params.Body{{end}}
diff --git a/internal/generate/templates/resptype_body_method.tpl b/internal/generate/templates/resptype_body_method.tpl
@@ -4,7 +4,7 @@
 	}{{end}}{{if .IsAppJSON}}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return nil, fmt.Errorf("encoding json body request failed: %v", err)
     }{{else}}
     b := params.Body{{end}}
@@ -44,7 +44,7 @@
     }
 
     var body {{.ResponseType}}
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
diff --git a/internal/generate/templates/resptype_method.tpl b/internal/generate/templates/resptype_method.tpl
@@ -37,7 +37,7 @@
     }
 
     var body {{.ResponseType}}
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
diff --git a/internal/generate/test_utils/paths_output b/internal/generate/test_utils/paths_output
@@ -49,7 +49,7 @@ func (c *Client) IpPoolList(ctx context.Context, params IpPoolListParams, ) (*Ip
     }
 
     var body IpPoolResultsPage
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -90,7 +90,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )
 	}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return nil, fmt.Errorf("encoding json body request failed: %v", err)
     }
 
@@ -127,7 +127,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -174,7 +174,7 @@ func (c *Client) IpPoolView(ctx context.Context, params IpPoolViewParams, ) (*Ip
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -189,7 +189,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )
 	}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return nil, fmt.Errorf("encoding json body request failed: %v", err)
     }
 
@@ -227,7 +227,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
diff --git a/internal/generate/test_utils/paths_output_expected b/internal/generate/test_utils/paths_output_expected
@@ -49,7 +49,7 @@ func (c *Client) IpPoolList(ctx context.Context, params IpPoolListParams, ) (*Ip
     }
 
     var body IpPoolResultsPage
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -90,7 +90,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )
 	}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return nil, fmt.Errorf("encoding json body request failed: %v", err)
     }
 
@@ -127,7 +127,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -174,7 +174,7 @@ func (c *Client) IpPoolView(ctx context.Context, params IpPoolViewParams, ) (*Ip
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
@@ -189,7 +189,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )
 	}
     // Encode the request body as json.
     b := new(bytes.Buffer)
-    if err := json.NewEncoder(b).Encode(params.Body); err != nil {
+    if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {
         return nil, fmt.Errorf("encoding json body request failed: %v", err)
     }
 
@@ -227,7 +227,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )
     }
 
     var body IpPool
-    if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
+    if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {
         return nil, fmt.Errorf("error decoding response body: %v", err)
     }
 
diff --git a/oxide/lib.go b/oxide/lib.go
@@ -6,6 +6,7 @@ package oxide
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -40,6 +41,37 @@ const (
 	defaultConfigDir = ".config" + string(filepath.Separator) + "oxide"
 )
 
+// JSONEncoder is an interface for encoding values to an output stream.
+type JSONEncoder interface {
+	Encode(v any) error
+}
+
+// JSONDecoder is an interface for decoding values from an input stream.
+type JSONDecoder interface {
+	Decode(v any) error
+}
+
+// JSONCodec is an interface that provides methods for creating JSON encoders and decoders.
+type JSONCodec interface {
+	NewEncoder(w io.Writer) JSONEncoder
+	NewDecoder(r io.Reader) JSONDecoder
+}
+
+func defaultJSONCodec() JSONCodec {
+	return stdJSONCodec{}
+}
+
+// stdJSONCodec is the default implementation using the standard library.
+type stdJSONCodec struct{}
+
+func (stdJSONCodec) NewEncoder(w io.Writer) JSONEncoder {
+	return json.NewEncoder(w)
+}
+
+func (stdJSONCodec) NewDecoder(r io.Reader) JSONDecoder {
+	return json.NewDecoder(r)
+}
+
 // Config is the configuration that can be set on a Client.
 type Config struct {
 	// Base URL of the Oxide API including the scheme. For example,
@@ -69,6 +101,10 @@ type Config struct {
 	// config.toml file for authentication. Will be overridden by
 	// the Profile field.
 	UseDefaultProfile bool
+
+	// A custom JSON codec for encoding and decoding. If not provided,
+	// the standard library's json.NewEncoder and json.NewDecoder will be used.
+	JSONCodec JSONCodec
 }
 
 // Client which conforms to the OpenAPI3 specification for this service.
@@ -85,6 +121,9 @@ type Client struct {
 
 	// The user agent string to add to every API request.
 	userAgent string
+
+	// JSON codec for encoding and decoding.
+	jsonCodec JSONCodec
 }
 
 type authCredentials struct {
@@ -106,6 +145,7 @@ func NewClient(cfg *Config) (*Client, error) {
 	profile := os.Getenv(ProfileEnvVar)
 	useDefaultProfile := false
 	userAgent := defaultUserAgent()
+	jsonCodec := defaultJSONCodec()
 	httpClient := &http.Client{
 		Timeout: 600 * time.Second,
 	}
@@ -138,6 +178,10 @@ func NewClient(cfg *Config) (*Client, error) {
 		if cfg.HTTPClient != nil {
 			httpClient = cfg.HTTPClient
 		}
+
+		if cfg.JSONCodec != nil {
+			jsonCodec = cfg.JSONCodec
+		}
 	}
 
 	if (profile != "" || useDefaultProfile) && (host != "" || token != "") {
@@ -187,6 +231,7 @@ func NewClient(cfg *Config) (*Client, error) {
 		host:      host,
 		userAgent: userAgent,
 		client:    httpClient,
+		jsonCodec: jsonCodec,
 	}
 
 	return client, nil
@@ -291,6 +336,16 @@ func parseBaseURL(baseURL string) (string, error) {
 	return b, nil
 }
 
+// newJSONEncoder creates a new JSON encoder for the given writer using the configured codec.
+func (c *Client) newJSONEncoder(w io.Writer) JSONEncoder {
+	return c.jsonCodec.NewEncoder(w)
+}
+
+// newJSONDecoder creates a new JSON decoder for the given reader using the configured codec.
+func (c *Client) newJSONDecoder(r io.Reader) JSONDecoder {
+	return c.jsonCodec.NewDecoder(r)
+}
+
 // buildRequest creates an HTTP request to interact with the Oxide API.
 func (c *Client) buildRequest(ctx context.Context, body io.Reader, method, uri string, params, queries map[string]string) (*http.Request, error) {
 	// Create the request.
diff --git a/oxide/lib_test.go b/oxide/lib_test.go
@@ -22,6 +22,17 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+// customJSONCodec is a custom JSON codec for testing custom codec functionality.
+type customJSONCodec struct{}
+
+func (customJSONCodec) NewEncoder(w io.Writer) JSONEncoder {
+	return json.NewEncoder(w)
+}
+
+func (customJSONCodec) NewDecoder(r io.Reader) JSONDecoder {
+	return json.NewDecoder(r)
+}
+
 func Test_buildRequest(t *testing.T) {
 	t.Parallel()
 
@@ -189,6 +200,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with valid client from env": {
@@ -203,6 +215,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with valid client from env and config": {
@@ -225,6 +238,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 500 * time.Second,
 				},
 				userAgent: "bob",
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with config, overrides env": {
@@ -245,6 +259,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with profile": {
@@ -261,6 +276,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with profile from env": {
@@ -278,6 +294,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with default profile": {
@@ -294,6 +311,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with config dir and default profile": {
@@ -310,6 +328,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with config dir and profile": {
@@ -326,6 +345,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with profile, overrides env": {
@@ -346,6 +366,7 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
 			},
 		},
 		"succeeds with host and token from different sources ": {
@@ -364,6 +385,25 @@ func Test_NewClient(t *testing.T) {
 					Timeout: 600 * time.Second,
 				},
 				userAgent: defaultUserAgent(),
+				jsonCodec: defaultJSONCodec(),
+			},
+		},
+		"succeeds with custom json codec": {
+			config: func(string) *Config {
+				return &Config{
+					Host:      "http://localhost",
+					Token:     "foo",
+					JSONCodec: customJSONCodec{},
+				}
+			},
+			expectedClient: &Client{
+				host:  "http://localhost/",
+				token: "foo",
+				client: &http.Client{
+					Timeout: 600 * time.Second,
+				},
+				userAgent: defaultUserAgent(),
+				jsonCodec: customJSONCodec{},
 			},
 		},
 		"fails with missing address using config": {
diff --git a/oxide/paths.go b/oxide/paths.go

Original file line number	Diff line number	Diff line change
`@@ -37,7 +37,7 @@`
`37`	`37`	`}`
`38`	`38`
`39`	`39`	`var body {{.ResponseType}}`
`40`		`- if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {`
	`40`	`+ if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {`
`41`	`41`	`return nil, fmt.Errorf("error decoding response body: %v", err)`
`42`	`42`	`}`
`43`	`43`
Original file line number	Diff line number	Diff line change
`@@ -49,7 +49,7 @@ func (c Client) IpPoolList(ctx context.Context, params IpPoolListParams, ) (Ip`
`49`	`49`	`}`
`50`	`50`
`51`	`51`	`var body IpPoolResultsPage`
`52`		`- if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {`
	`52`	`+ if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {`
`53`	`53`	`return nil, fmt.Errorf("error decoding response body: %v", err)`
`54`	`54`	`}`
`55`	`55`
`@@ -90,7 +90,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )`
`90`	`90`	`}`
`91`	`91`	`// Encode the request body as json.`
`92`	`92`	`b := new(bytes.Buffer)`
`93`		`- if err := json.NewEncoder(b).Encode(params.Body); err != nil {`
	`93`	`+ if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {`
`94`	`94`	`return nil, fmt.Errorf("encoding json body request failed: %v", err)`
`95`	`95`	`}`
`96`	`96`
`@@ -127,7 +127,7 @@ func (c *Client) IpPoolCreate(ctx context.Context, params IpPoolCreateParams, )`
`127`	`127`	`}`
`128`	`128`
`129`	`129`	`var body IpPool`
`130`		`- if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {`
	`130`	`+ if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {`
`131`	`131`	`return nil, fmt.Errorf("error decoding response body: %v", err)`
`132`	`132`	`}`
`133`	`133`
`@@ -174,7 +174,7 @@ func (c Client) IpPoolView(ctx context.Context, params IpPoolViewParams, ) (Ip`
`174`	`174`	`}`
`175`	`175`
`176`	`176`	`var body IpPool`
`177`		`- if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {`
	`177`	`+ if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {`
`178`	`178`	`return nil, fmt.Errorf("error decoding response body: %v", err)`
`179`	`179`	`}`
`180`	`180`
`@@ -189,7 +189,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )`
`189`	`189`	`}`
`190`	`190`	`// Encode the request body as json.`
`191`	`191`	`b := new(bytes.Buffer)`
`192`		`- if err := json.NewEncoder(b).Encode(params.Body); err != nil {`
	`192`	`+ if err := c.newJSONEncoder(b).Encode(params.Body); err != nil {`
`193`	`193`	`return nil, fmt.Errorf("encoding json body request failed: %v", err)`
`194`	`194`	`}`
`195`	`195`
`@@ -227,7 +227,7 @@ func (c *Client) IpPoolUpdate(ctx context.Context, params IpPoolUpdateParams, )`
`227`	`227`	`}`
`228`	`228`
`229`	`229`	`var body IpPool`
`230`		`- if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {`
	`230`	`+ if err := c.newJSONDecoder(resp.Body).Decode(&body); err != nil {`
`231`	`231`	`return nil, fmt.Errorf("error decoding response body: %v", err)`
`232`	`232`	`}`
`233`	`233`