improve JSONSchemaType errors

typescript seems to report errors with the last member of a valid union first, so this rearranges the type so the simple union types come first, and the type that represents the meaty types comes last. This should help make errors like the one in #1521 more clear.
ajv-validator · Apr 1, 2021 · 314a2db · 314a2db
1 parent 24dba5c
commit 314a2db
Showing 1 changed file with 24 additions and 23 deletions.
diff --git a/lib/types/json-schema.ts b/lib/types/json-schema.ts
@@ -24,6 +24,30 @@ interface StringKeywords {
 }
 
 export type JSONSchemaType<T, _partial extends boolean = false> = (
+  | // these two unions allow arbitrary unions of types
+  {
+      anyOf: readonly JSONSchemaType<T, _partial>[]
+    }
+  | {
+      oneOf: readonly JSONSchemaType<T, _partial>[]
+    }
+  // this union allows for { type: (primitive)[] } style schemas
+  | ({
+      type: (T extends number
+        ? JSONType<"number" | "integer", _partial>
+        : T extends string
+        ? JSONType<"string", _partial>
+        : T extends boolean
+        ? JSONType<"boolean", _partial>
+        : never)[]
+    } & (T extends number
+      ? NumberKeywords
+      : T extends string
+      ? StringKeywords
+      : T extends boolean
+      ? unknown
+      : never))
+  // this covers "normal" types; it's last so typescript looks to it first for errors
   | ((T extends number
       ? {
           type: JSONType<"number" | "integer", _partial>
@@ -91,29 +115,6 @@ export type JSONSchemaType<T, _partial extends boolean = false> = (
       else?: PartialSchema<T>
       not?: PartialSchema<T>
     })
-  // these two unions allow arbitrary unions of types
-  | {
-      anyOf: readonly JSONSchemaType<T, _partial>[]
-    }
-  | {
-      oneOf: readonly JSONSchemaType<T, _partial>[]
-    }
-  // this union allows for { type: (primitive)[] } style schemas
-  | ({
-      type: (T extends number
-        ? JSONType<"number" | "integer", _partial>
-        : T extends string
-        ? JSONType<"string", _partial>
-        : T extends boolean
-        ? JSONType<"boolean", _partial>
-        : never)[]
-    } & (T extends number
-      ? NumberKeywords
-      : T extends string
-      ? StringKeywords
-      : T extends boolean
-      ? unknown
-      : never))
 ) & {
   [keyword: string]: any
   $id?: string