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|  | 1 | +# OpenAI Go Migration Guide | 
|  | 2 | + | 
|  | 3 | +<a href="https://pkg.go.dev/github.com/openai/openai-go"><img src="https://pkg.go.dev/badge/github.com/openai/openai-go.svg" alt="Go Reference"></a> | 
|  | 4 | + | 
|  | 5 | +This SDK includes breaking changes to improve the ergonomics of constructing parameters and accessing responses. | 
|  | 6 | + | 
|  | 7 | +To reduce verbosity, the `openai.F(...)` and `param.Field[T]` have been removed. | 
|  | 8 | +All calls to `openai.F(...)` can be deleted. | 
|  | 9 | + | 
|  | 10 | +The SDK now uses the <code>\`json:"...,omitzero"\`</code> struct tag to omit fields. Nested structs, arrays and maps | 
|  | 11 | +can be declared like normal. | 
|  | 12 | + | 
|  | 13 | +The old SDK used interfaces for unions in requests, which required | 
|  | 14 | +a type assertion to access variants and fields. The new design uses | 
|  | 15 | +structs with a field for each variant, wherein only one field can be set. | 
|  | 16 | +These struct unions also expose 'Get' methods to access and mutate subfields | 
|  | 17 | +which may be shared by multiple variants. | 
|  | 18 | + | 
|  | 19 | +# Request parameters | 
|  | 20 | + | 
|  | 21 | +## Required primitives parameters serialize their zero values (`string`, `int64`, etc.) | 
|  | 22 | + | 
|  | 23 | +> [!CAUTION] | 
|  | 24 | +> | 
|  | 25 | +> **This change can cause new behavior in existing code, without compiler warnings.** | 
|  | 26 | +
 | 
|  | 27 | +While migrating, ensure that all required fields are explicitly set. A required primitive | 
|  | 28 | +field `Age` will use the <code>\`json:"age,required"\`</code> struct tag without `omitzero`. | 
|  | 29 | + | 
|  | 30 | +If a required primitive field is not set, the zero value will be serialized. | 
|  | 31 | +This was not the case in with `param.Field[T]`. | 
|  | 32 | + | 
|  | 33 | +```diff | 
|  | 34 | +type FooParams struct { | 
|  | 35 | +-        Age  param.Field[int64]  `json:"age,required"` | 
|  | 36 | +-        Name param.Field[string] `json:"name"` | 
|  | 37 | ++        Age  int64               `json:"age,required"` // <== Notice no omitzero | 
|  | 38 | ++        Name param.Opt[string]   `json:"name,omitzero"` | 
|  | 39 | +} | 
|  | 40 | +``` | 
|  | 41 | + | 
|  | 42 | +<table> | 
|  | 43 | +<tr> | 
|  | 44 | +<th>Previous</th> | 
|  | 45 | +<th>New</th> | 
|  | 46 | +</tr> | 
|  | 47 | +<tr> | 
|  | 48 | +<td> | 
|  | 49 | + | 
|  | 50 | +```go | 
|  | 51 | +_ = FooParams{ | 
|  | 52 | +    Name: openai.String("Jerry") | 
|  | 53 | +} | 
|  | 54 | +`{"name": "Jerry"}` // (after serialization) | 
|  | 55 | +``` | 
|  | 56 | + | 
|  | 57 | +</td> | 
|  | 58 | +<td> | 
|  | 59 | + | 
|  | 60 | +```go | 
|  | 61 | +_ = FooParams{ | 
|  | 62 | +    Name: openai.String("Jerry") | 
|  | 63 | +} | 
|  | 64 | +`{"name": "Jerry", "age": 0}` // <== Notice the age field | 
|  | 65 | +``` | 
|  | 66 | + | 
|  | 67 | +</td> | 
|  | 68 | +</tr> | 
|  | 69 | +</table> | 
|  | 70 | + | 
|  | 71 | +The required field `"age"` is now present as `0`. Fields without the <code>\`json:"...,omitzero"\`</code> struct tag | 
|  | 72 | +are always serialized, including their zero values. | 
|  | 73 | + | 
|  | 74 | +## Transition from `param.Field[T]` to `omitzero` | 
|  | 75 | + | 
|  | 76 | +The `openai.F(...)` function and `param.Field[T]` type are no longer present in the new SDK. | 
|  | 77 | + | 
|  | 78 | +To represent omitted fields, the SDK uses <a href="https://pkg.go.dev/encoding/json#Marshal"><code>\`json:"...,omitzero"\`</code> semantics</a> from Go 1.24+ for JSON encoding[^1]. `omitzero` always omits fields | 
|  | 79 | +with zero values. | 
|  | 80 | + | 
|  | 81 | +In all cases other than optional primitives, `openai.F()` can simply be removed. | 
|  | 82 | +For optional primitive types, such as `param.Opt[string]`, you can use `openai.String(string)` to construct the value. | 
|  | 83 | +Similar functions exist for other primitive types like `openai.Int(int)`, `openai.Bool(bool)`, etc. | 
|  | 84 | + | 
|  | 85 | +`omitzero` is used for fields whose type is either a struct, slice, map, string enum, | 
|  | 86 | +or wrapped optional primitive (e.g. `param.Opt[T]`). Required primitive fields don't use `omitzero`. | 
|  | 87 | + | 
|  | 88 | +**Example User Code: Constructing a request** | 
|  | 89 | + | 
|  | 90 | +```diff | 
|  | 91 | +foo = FooParams{ | 
|  | 92 | +-    RequiredString: openai.String("hello"), | 
|  | 93 | ++    RequiredString: "hello", | 
|  | 94 | + | 
|  | 95 | +-    OptionalString: openai.String("hi"), | 
|  | 96 | ++    OptionalString: openai.String("hi"), | 
|  | 97 | + | 
|  | 98 | +-    Array: openai.F([]BarParam{ | 
|  | 99 | +-        BarParam{Prop: ... } | 
|  | 100 | +-    }), | 
|  | 101 | ++    Array: []BarParam{ | 
|  | 102 | ++        BarParam{Prop: ... } | 
|  | 103 | ++    }, | 
|  | 104 | + | 
|  | 105 | +-    RequiredObject: openai.F(BarParam{ ... }), | 
|  | 106 | ++    RequiredObject: BarParam{ ... }, | 
|  | 107 | + | 
|  | 108 | +-    OptionalObject: openai.F(BarParam{ ... }), | 
|  | 109 | ++    OptionalObject: BarParam{ ... }, | 
|  | 110 | + | 
|  | 111 | +-    StringEnum: openai.F[BazEnum]("baz-ok"), | 
|  | 112 | ++    StringEnum: "baz-ok", | 
|  | 113 | +} | 
|  | 114 | +``` | 
|  | 115 | + | 
|  | 116 | +**Internal SDK Code: Fields of a request struct:** | 
|  | 117 | + | 
|  | 118 | +```diff | 
|  | 119 | +type FooParams struct { | 
|  | 120 | +-    RequiredString param.Field[string]   `json:"required_string,required"` | 
|  | 121 | ++    RequiredString string                `json:"required_string,required"` | 
|  | 122 | + | 
|  | 123 | +-    OptionalString param.Field[string]   `json:"optional_string"` | 
|  | 124 | ++    OptionalString param.Opt[string]     `json:"optional_string,omitzero"` | 
|  | 125 | + | 
|  | 126 | +-    Array param.Field[[]BarParam]        `json"array"` | 
|  | 127 | ++    Array []BarParam                     `json"array,omitzero"` | 
|  | 128 | + | 
|  | 129 | +-    Map param.Field[map[string]BarParam] `json"map"` | 
|  | 130 | ++    Map map[string]BarParam              `json"map,omitzero"` | 
|  | 131 | + | 
|  | 132 | +-    RequiredObject param.Field[BarParam] `json:"required_object,required"` | 
|  | 133 | ++    RequiredObject BarParam              `json:"required_object,omitzero,required"` | 
|  | 134 | + | 
|  | 135 | +-    OptionalObject param.Field[BarParam] `json:"optional_object"` | 
|  | 136 | ++    OptionalObject BarParam              `json:"optional_object,omitzero"` | 
|  | 137 | + | 
|  | 138 | +-    StringEnum     param.Field[BazEnum]  `json:"string_enum"` | 
|  | 139 | ++    StringEnum     BazEnum               `json:"string_enum,omitzero"` | 
|  | 140 | +} | 
|  | 141 | +``` | 
|  | 142 | + | 
|  | 143 | +## Request Unions: Removing interfaces and moving to structs | 
|  | 144 | + | 
|  | 145 | +For a type `AnimalUnionParam` which could be either a `CatParam | DogParam`. | 
|  | 146 | + | 
|  | 147 | +<table> | 
|  | 148 | +<tr><th>Previous</th> <th>New</th></tr> | 
|  | 149 | +<tr> | 
|  | 150 | +<td> | 
|  | 151 | + | 
|  | 152 | +```go | 
|  | 153 | +type AnimalParam interface { | 
|  | 154 | +	ImplAnimalParam() | 
|  | 155 | +} | 
|  | 156 | + | 
|  | 157 | +func (Dog)         ImplAnimalParam() {} | 
|  | 158 | +func (Cat)         ImplAnimalParam() {} | 
|  | 159 | +``` | 
|  | 160 | + | 
|  | 161 | +</td> | 
|  | 162 | +<td> | 
|  | 163 | + | 
|  | 164 | +```go | 
|  | 165 | +type AnimalUnionParam struct { | 
|  | 166 | +	OfCat 	 *Cat              `json:",omitzero,inline` | 
|  | 167 | +	OfDog    *Dog              `json:",omitzero,inline` | 
|  | 168 | +} | 
|  | 169 | +``` | 
|  | 170 | + | 
|  | 171 | +</td> | 
|  | 172 | +</tr> | 
|  | 173 | + | 
|  | 174 | +<tr style="background:rgb(209, 217, 224)"> | 
|  | 175 | +<td> | 
|  | 176 | + | 
|  | 177 | +```go | 
|  | 178 | +var dog AnimalParam = DogParam{ | 
|  | 179 | +	Name: "spot", ... | 
|  | 180 | +} | 
|  | 181 | +var cat AnimalParam = CatParam{ | 
|  | 182 | +	Name: "whiskers", ... | 
|  | 183 | +} | 
|  | 184 | +``` | 
|  | 185 | + | 
|  | 186 | +</td> | 
|  | 187 | +<td> | 
|  | 188 | + | 
|  | 189 | +```go | 
|  | 190 | +dog := AnimalUnionParam{ | 
|  | 191 | +	OfDog: &DogParam{Name: "spot", ... }, | 
|  | 192 | +} | 
|  | 193 | +cat := AnimalUnionParam{ | 
|  | 194 | +	OfCat: &CatParam{Name: "whiskers", ... }, | 
|  | 195 | +} | 
|  | 196 | +``` | 
|  | 197 | + | 
|  | 198 | +</td> | 
|  | 199 | +</tr> | 
|  | 200 | + | 
|  | 201 | +<tr> | 
|  | 202 | +<td> | 
|  | 203 | + | 
|  | 204 | +```go | 
|  | 205 | +var name string | 
|  | 206 | +switch v := animal.(type) { | 
|  | 207 | +case Dog: | 
|  | 208 | +	name = v.Name | 
|  | 209 | +case Cat: | 
|  | 210 | +	name = v.Name | 
|  | 211 | +} | 
|  | 212 | +``` | 
|  | 213 | + | 
|  | 214 | +</td> | 
|  | 215 | +<td> | 
|  | 216 | + | 
|  | 217 | +```go | 
|  | 218 | +// Accessing fields | 
|  | 219 | +var name *string = animal.GetName() | 
|  | 220 | +``` | 
|  | 221 | + | 
|  | 222 | +</td> | 
|  | 223 | +</tr> | 
|  | 224 | +</table> | 
|  | 225 | + | 
|  | 226 | +## Sending explicit `null` values | 
|  | 227 | + | 
|  | 228 | +The old SDK had a function `param.Null[T]()` which could set `param.Field[T]` to `null`. | 
|  | 229 | + | 
|  | 230 | +The new SDK uses `param.Null[T]()` for to set a `param.Opt[T]` to `null`, | 
|  | 231 | +but `param.NullStruct[T]()` to set a param struct `T` to `null`. | 
|  | 232 | + | 
|  | 233 | +```diff | 
|  | 234 | +- var nullPrimitive param.Field[int64] = param.Null[int64]() | 
|  | 235 | ++ var nullPrimitive param.Opt[int64]   = param.Null[int64]() | 
|  | 236 | + | 
|  | 237 | +- var nullStruct param.Field[BarParam] = param.Null[BarParam]() | 
|  | 238 | ++ var nullStruct BarParam              = param.NullStruct[BarParam]() | 
|  | 239 | +``` | 
|  | 240 | + | 
|  | 241 | +## Sending custom values | 
|  | 242 | + | 
|  | 243 | +The `openai.Raw[T](any)` function has been removed. All request structs now support a | 
|  | 244 | +`.WithExtraField(map[string]any)` method to customize the fields. | 
|  | 245 | + | 
|  | 246 | +```diff | 
|  | 247 | +foo := FooParams{ | 
|  | 248 | +     A: param.String("hello"), | 
|  | 249 | +-    B: param.Raw[string](12) // sending `12` instead of a string | 
|  | 250 | +} | 
|  | 251 | ++ foo.SetExtraFields(map[string]any{ | 
|  | 252 | ++    "B": 12, | 
|  | 253 | ++ }) | 
|  | 254 | +``` | 
|  | 255 | + | 
|  | 256 | +# Response Properties | 
|  | 257 | + | 
|  | 258 | +## Checking for presence of optional fields | 
|  | 259 | + | 
|  | 260 | +The `.IsNull()` method has been changed to `.Valid()` to better reflect its behavior. | 
|  | 261 | + | 
|  | 262 | +```diff | 
|  | 263 | +- if !resp.Foo.JSON.Bar.IsNull() { | 
|  | 264 | ++ if resp.Foo.JSON.Bar.Valid() { | 
|  | 265 | +    println("bar is present:", resp.Foo.Bar) | 
|  | 266 | +} | 
|  | 267 | +``` | 
|  | 268 | + | 
|  | 269 | +| Previous       | New                      | Returns true for values | | 
|  | 270 | +| -------------- | ------------------------ | ----------------------- | | 
|  | 271 | +| `.IsNull()`    | `!.Valid()`              | `null` or Omitted       | | 
|  | 272 | +| `.IsMissing()` | `.Raw() == resp.Omitted` | Omitted                 | | 
|  | 273 | +|                | `.Raw() == resp.Null`    | | 
|  | 274 | + | 
|  | 275 | +## Checking Raw JSON of a response | 
|  | 276 | + | 
|  | 277 | +The `.RawJSON()` method has moved to the parent of the `.JSON` property. | 
|  | 278 | + | 
|  | 279 | +```diff | 
|  | 280 | +- resp.Foo.JSON.RawJSON() | 
|  | 281 | ++ resp.Foo.RawJSON() | 
|  | 282 | +``` | 
|  | 283 | + | 
|  | 284 | +[^1]: The SDK doesn't require Go 1.24, despite supporting the `omitzero` feature | 
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