Allow customizing the type of scalars in queries generator (#1313)

Add the ability for users of the queries generator to override
the TypeScript types of custom scalar variables via `OverrideCodecType`.
The default scalar types are non-overrideable.

Author: freeatnet

packages/gel/src/codecTypeRegistry.ts

@@ -0,0 +1,7 @@
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface OverrideCodecType {}
+
+export type ResolvedCodecType<TDbTypeName, TDefaultTsType> =
+  TDbTypeName extends keyof OverrideCodecType
+    ? OverrideCodecType[TDbTypeName]
+    : TDefaultTsType;

packages/gel/src/index.shared.ts

@@ -53,10 +53,14 @@ export * from "./errors";
 
 export type { Codecs } from "./codecs/codecs";
 
+export type { OverrideCodecType, ResolvedCodecType } from "./codecTypeRegistry";
+
 /* Private APIs */
 import type * as codecs from "./codecs/ifaces";
+import { ScalarCodec } from "./codecs/ifaces";
 import * as reg from "./codecs/registry";
 import * as buf from "./primitives/buffer";
 export const _CodecsRegistry = reg.CodecsRegistry;
 export const _ReadBuffer = buf.ReadBuffer;
 export type _ICodec = codecs.ICodec;
+export const _ScalarCodec = ScalarCodec;

packages/gel/src/reflection/analyzeQuery.ts

@@ -23,9 +23,14 @@ type QueryType = {
   imports: Set<string>;
 };
 
+export type AnalyzeQueryOptions = {
+  useResolvedCodecType?: boolean;
+};
+
 export async function analyzeQuery(
   client: Client,
   query: string,
+  { useResolvedCodecType = false }: AnalyzeQueryOptions = {},
 ): Promise<QueryType> {
   const {
     cardinality,
@@ -34,11 +39,18 @@ export async function analyzeQuery(
     out: outCodec,
   } = await client.describe(query);
 
+  const generators: CodecGeneratorMap = useResolvedCodecType
+    ? new Map([...defaultCodecGenerators, resolvedCodecTypeScalarTypeGenerator])
+    : defaultCodecGenerators;
+
   const args = generateTSTypeFromCodec(inCodec, Cardinality.One, {
     optionalNulls: true,
     readonly: true,
+    generators,
+  });
+  const result = generateTSTypeFromCodec(outCodec, cardinality, {
+    generators,
   });
-  const result = generateTSTypeFromCodec(outCodec, cardinality);
 
   const imports = args.imports.merge(result.imports);
   return {
@@ -160,6 +172,21 @@ const getSortPriority = (field: FieldDef) => {
   return 8;
 };
 
+const resolvedCodecTypeScalarTypeGenerator = genDef(
+  ScalarCodec,
+  (codec, ctx) => {
+    if (codec.tsModule) {
+      ctx.imports.add(codec.tsModule, codec.tsType);
+    }
+    const isCustomScalar = !codec.typeName.startsWith("std::");
+    if (isCustomScalar) {
+      ctx.imports.add("gel", "ResolvedCodecType");
+      return `ResolvedCodecType<"${codec.typeName}", ${codec.tsType}>`;
+    }
+    return codec.tsType;
+  },
+);
+
 export const defaultCodecGenerators: CodecGeneratorMap = new Map([
   genDef(NullCodec, () => "null"),
   genDef(EnumCodec, (codec) => {

packages/generate/src/cli.ts

@@ -206,6 +206,9 @@ const run = async () => {
       case "--use-http-client":
         options.useHttpClient = true;
         break;
+      case "--use-resolved-codec-type":
+        options.useResolvedCodecType = true;
+        break;
       case "--target": {
         if (
           generator === Generator.Interfaces ||

packages/generate/src/commandutil.ts

@@ -16,6 +16,7 @@ export interface CommandOptions {
   forceOverwrite?: boolean;
   updateIgnoreFile?: boolean;
   useHttpClient?: boolean;
+  useResolvedCodecType?: boolean;
   future?: Partial<Record<keyof typeof defaultFutureFlags, boolean>>;
   patterns?: string[];
 }

packages/generate/src/queries.ts

@@ -66,7 +66,9 @@ currently supported.`);
 
         try {
           const query = await readFileUtf8(p);
-          const types = await $.analyzeQuery(client, query);
+          const types = await $.analyzeQuery(client, query, {
+            useResolvedCodecType: params.options.useResolvedCodecType,
+          });
           console.log(`   ${prettyPath}`);
           const files = generateFiles({
             target: params.options.target!,
@@ -120,7 +122,9 @@ currently supported.`);
     try {
       const query = await readFileUtf8(p);
       if (!query) return;
-      const types = await $.analyzeQuery(client, query);
+      const types = await $.analyzeQuery(client, query, {
+        useResolvedCodecType: params.options.useResolvedCodecType,
+      });
       const files = generateFiles({
         target: params.options.target!,
         path: p,