refactor: allow narrowing IRParameter into more specific types

packages/openapi-code-generator/src/core/input.ts

@@ -10,6 +10,7 @@ import type {
   Responses,
   Schema,
   Server,
+  Style,
   xInternalPreproccess,
 } from "./openapi-types"
 import type {
@@ -22,6 +23,11 @@ import type {
   IRModelString,
   IROperation,
   IRParameter,
+  IRParameterBase,
+  IRParameterCookie,
+  IRParameterHeader,
+  IRParameterPath,
+  IRParameterQuery,
   IRPreprocess,
   IRRef,
   IRResponse,
@@ -333,18 +339,142 @@ export class Input {
     return parameters
       .map((it) => this.loader.parameter(it))
       .map((it: Parameter): IRParameter => {
-        return {
+        const base = {
           name: it.name,
-          in: it.in,
           schema: this.normalizeSchemaObject(it.schema),
           description: it.description,
           required: it.required ?? false,
           deprecated: it.deprecated ?? false,
-          allowEmptyValue: it.allowEmptyValue ?? false,
+        } satisfies Omit<IRParameterBase, "explode">
+
+        function throwUnsupportedStyle(style: Style): never {
+          throw new Error(
+            `unsupported parameter style: '${style}' for in: '${it.in}'`,
+          )
+        }
+
+        switch (it.in) {
+          case "path": {
+            const style = it.style ?? "simple"
+            const explode = this.explodeForParameter(it, style)
+
+            if (!this.isStyleForPathParameter(style)) {
+              throwUnsupportedStyle(style)
+            }
+
+            return {
+              ...base,
+              in: "path",
+              style,
+              explode,
+            } satisfies IRParameterPath
+          }
+
+          case "query": {
+            const style = it.style ?? "form"
+            const explode = this.explodeForParameter(it, style)
+
+            if (!this.isStyleForQueryParameter(style)) {
+              throwUnsupportedStyle(style)
+            }
+
+            return {
+              ...base,
+              in: "query",
+              style,
+              explode,
+              allowEmptyValue: it.allowEmptyValue ?? false,
+            } satisfies IRParameterQuery
+          }
+
+          case "header": {
+            const style = it.style ?? "simple"
+            const explode = this.explodeForParameter(it, style)
+
+            if (!this.isStyleForHeaderParameter(style)) {
+              throwUnsupportedStyle(style)
+            }
+
+            return {
+              ...base,
+              in: "header",
+              style,
+              explode,
+            } satisfies IRParameterHeader
+          }
+
+          case "cookie": {
+            const style = it.style ?? "form"
+            const explode = this.explodeForParameter(it, style)
+
+            if (!this.isStyleForCookieParameter(style)) {
+              throwUnsupportedStyle(style)
+            }
+
+            return {
+              ...base,
+              in: "cookie",
+              style,
+              explode,
+            } satisfies IRParameterCookie
+          }
+
+          default: {
+            throw new Error(
+              `unsupported parameter location: '${it.in satisfies never}'`,
+            )
+          }
         }
       })
   }
 
+  private isStyleForPathParameter(
+    style: Style,
+  ): style is IRParameterPath["style"] {
+    return ["simple", "label", "matrix", "template"].includes(style)
+  }
+
+  private isStyleForQueryParameter(
+    style: Style,
+  ): style is IRParameterQuery["style"] {
+    return ["form", "spaceDelimited", "pipeDelimited", "deepObject"].includes(
+      style,
+    )
+  }
+
+  private isStyleForHeaderParameter(
+    style: Style,
+  ): style is IRParameterHeader["style"] {
+    return ["simple"].includes(style)
+  }
+
+  private isStyleForCookieParameter(
+    style: Style,
+  ): style is IRParameterCookie["style"] {
+    if (style === "cookie") {
+      // todo: openapi v3.2.0
+      throw new Error("support for style: cookie not implemented.")
+    }
+
+    return ["form"].includes(style)
+  }
+
+  private explodeForParameter(parameter: Parameter, style: Style): boolean {
+    if (typeof parameter.explode === "boolean") {
+      return parameter.explode
+    }
+
+    /**
+     * "When style is "form" or "cookie", the default value is true. For all other styles, the default value is false."
+     * ref: {@link https://spec.openapis.org/oas/v3.2.0.html#parameter-explode}
+     */
+    if (style === "form" || style === "cookie") {
+      return true
+    }
+
+    return false
+  }
+
   private normalizeOperationId(
     operationId: string | undefined,
     method: string,

packages/openapi-code-generator/src/core/openapi-types-normalized.ts

@@ -123,16 +123,52 @@ export interface IRServerVariable {
   description: string | undefined
 }
 
-export interface IRParameter {
+export interface IRParameterBase {
   name: string
-  in: "path" | "query" | "header" | "cookie" | "body"
-  schema: MaybeIRModel
   description: string | undefined
   required: boolean
   deprecated: boolean
-  allowEmptyValue: boolean
+  schema: MaybeIRModel
+  explode: boolean | undefined
+}
+
+export interface IRParameterPath extends IRParameterBase {
+  in: "path"
+  // todo: matrix/label not supported
+  style: "matrix" | "label" | "simple"
 }
 
+export interface IRParameterQuery extends IRParameterBase {
+  in: "query"
+  style: "form" | "spaceDelimited" | "pipeDelimited" | "deepObject" // default: form
+  explode: boolean | undefined // default: true for form/cookie, false for other styles
+  allowEmptyValue: boolean //default: false
+}
+
+export interface IRParameterHeader extends IRParameterBase {
+  in: "header"
+  style: "simple"
+}
+
+export interface IRParameterCookie extends IRParameterBase {
+  in: "cookie"
+  style: "form"
+  // todo: openapi v3.2.0 - support style: "cookie"
+  // | "cookie"
+}
+
+// note: not part of spec, but used internally
+export interface IRParameterRequestBody extends IRParameterBase {
+  in: "body"
+}
+
+export type IRParameter =
+  | IRParameterPath
+  | IRParameterQuery
+  | IRParameterHeader
+  | IRParameterCookie
+  | IRParameterRequestBody
+
 export interface IROperation {
   route: string
   method: HttpMethod

packages/openapi-code-generator/src/core/openapi-types.ts

@@ -152,6 +152,7 @@ export type Style =
   | "pipeDelimited"
   | "simple"
   | "spaceDelimited"
+  | "cookie"
 
 export interface Encoding {
   allowReserved?: boolean
@@ -202,7 +203,15 @@ export interface Header {
 export interface Parameter {
   name: string
   in: "path" | "query" | "header" | "cookie"
+  // todo: openapi v3.2.0 - support querystring
+  // | "querystring"
   schema: Schema | Reference
+  // todo: support content on parameters
+  // content?: {
+  //   [contentType: string]: MediaType
+  // }
+  style?: Style
+  explode?: boolean
   description?: string
   required?: boolean
   deprecated?: boolean

packages/openapi-code-generator/src/typescript/common/typescript-common.ts

@@ -3,7 +3,7 @@ import type {Encoding} from "../../core/openapi-types"
 import type {
   IRMediaType,
   IROperation,
-  IRParameter,
+  IRParameterRequestBody,
 } from "../../core/openapi-types-normalized"
 import {isDefined} from "../../core/utils"
 
@@ -148,7 +148,7 @@ export type Serializer = "JSON.stringify" | "String" | "URLSearchParams"
 
 export type RequestBodyAsParameter = {
   isSupported: boolean
-  parameter: IRParameter
+  parameter: IRParameterRequestBody
   contentType: string
   serializer: Serializer | undefined
   encoding?: Record<string, Encoding>
@@ -249,8 +249,8 @@ export function requestBodyAsParameter(
         description: requestBody.description,
         in: "body",
         required: requestBody.required,
+        explode: undefined,
         schema: result.mediaType.schema,
-        allowEmptyValue: false,
         deprecated: false,
       },
       serializer: result.serializer,
@@ -276,8 +276,8 @@ export function requestBodyAsParameter(
       description: requestBody.description,
       in: "body",
       required: requestBody.required,
+      explode: undefined,
       schema: {type: "never", nullable: false, readOnly: false},
-      allowEmptyValue: false,
       deprecated: false,
     },
     serializer: undefined,

pnpm-workspace.yaml

@@ -13,6 +13,7 @@ ignoredBuiltDependencies:
   - '@parcel/watcher'
   - '@swc/core'
   - esbuild
+  - lmdb
   - nx
   - sharp
   - unrs-resolver