[visitor-plugin-common] fix: satisfy strict mode in selection-set-to-object, client-side-base-visitor and base-documents-visitor (#4683)

.changeset/strict-visitor-plugin-common-documents.md

@@ -0,0 +1,16 @@
+---
+'@graphql-codegen/visitor-plugin-common': patch
+---
+
+Fix type errors in `visitor-plugin-common` (`selection-set-to-object`, `client-side-base-visitor` and `base-documents-visitor`) under `strict: true`:
+
+- `BaseDocumentsVisitor._selectionSetToObject` is optional, since it is only set by `setSelectionSetHandler`. `FragmentDefinition` and `OperationDefinition` throw a descriptive error when it is not set, and `FragmentDefinition` throws one when the fragment's type condition is not in the schema.
+- `BaseDocumentsVisitor.FragmentDefinition` may return `null`, which it already returns when `generateOperationTypes` is `false`.
+- `ClientSideBaseVisitor.buildOperation` may return `null`, which its base implementation already returns.
+- `SelectionSetToObject.transformSelectionSet` declares its return type, and throws a descriptive error when the instance has no selection set.
+- `LinkField`'s `alias` is optional, matching the link fields built for fields without an alias.
+- `BaseSelectionSetProcessor.typeCache` is keyed by `Location | undefined`, since selection sets parsed with `noLocation` have no `loc`.
+- `getPossibleTypes` accepts any `GraphQLType` or `undefined`, which it already handles by unwrapping lists and non-nulls and returning no types, and returns a copy of the schema's possible types instead of the schema's own readonly array.
+- `OperationVariablesToObject.transform` accepts `undefined`, which it already handles by returning `null`.
+
+Generated output is unchanged.

packages/plugins/other/visitor-plugin-common/src/base-documents-visitor.ts

@@ -370,7 +370,7 @@ export class BaseDocumentsVisitor<
 > extends BaseVisitor<TRawConfig, TPluginConfig> {
   protected _unnamedCounter = 1;
   protected _variablesTransfomer: OperationVariablesToObject;
-  protected _selectionSetToObject: SelectionSetToObject;
+  protected _selectionSetToObject?: SelectionSetToObject;
   protected _globalDeclarations: Set<string> = new Set<string>();
 
   constructor(
@@ -469,12 +469,23 @@ export class BaseDocumentsVisitor<
     });
   }
 
-  FragmentDefinition(node: FragmentDefinitionNode): string {
+  FragmentDefinition(node: FragmentDefinitionNode): string | null {
     if (!this.config.generateOperationTypes) {
       return null;
     }
 
+    if (!this._selectionSetToObject) {
+      throw new Error('Unable to visit fragments: call "setSelectionSetHandler" first');
+    }
+
     const fragmentRootType = this._schema.getType(node.typeCondition.name.value);
+
+    if (!fragmentRootType) {
+      throw new Error(
+        `Unable to find schema type "${node.typeCondition.name.value}" for fragment "${node.name.value}"!`,
+      );
+    }
+
     const selectionSet = this._selectionSetToObject.createNext(fragmentRootType, node.selectionSet);
     const fragmentSuffix = this.getFragmentSuffix(node);
     return [
@@ -518,6 +529,10 @@ export class BaseDocumentsVisitor<
       throw new Error(`Unable to find root schema type for operation type "${node.operation}"!`);
     }
 
+    if (!this._selectionSetToObject) {
+      throw new Error('Unable to visit operations: call "setSelectionSetHandler" first');
+    }
+
     const selectionSet = this._selectionSetToObject.createNext(
       operationRootType,
       node.selectionSet,

packages/plugins/other/visitor-plugin-common/src/client-side-base-visitor.ts

@@ -256,7 +256,7 @@ export class ClientSideBaseVisitor<
     fragments: LoadedFragment[],
     rawConfig: TRawConfig,
     additionalConfig: Partial<TPluginConfig>,
-    documents?: Types.DocumentFile[],
+    documents: Types.DocumentFile[] = [],
   ) {
     super(rawConfig, {
       scalars: buildScalarsFromConfig(_schema, rawConfig),
@@ -464,10 +464,10 @@ export class ClientSideBaseVisitor<
   ): Record<string, any> | void | undefined {
     let meta: Record<string, any> | void | undefined;
 
-    if (node.kind === Kind.OPERATION_DEFINITION) {
+    if (node.kind === Kind.OPERATION_DEFINITION && this._onExecutableDocumentNode) {
       meta = this._onExecutableDocumentNode({
         kind: Kind.DOCUMENT,
-        definitions,
+        definitions: definitions || [],
       });
     }
 
@@ -487,8 +487,8 @@ export class ClientSideBaseVisitor<
   } {
     const deferredFields: { [fargmentName: string]: string[] } = {};
     const queue: SelectionNode[] = [...node.selectionSet.selections];
-    while (queue.length) {
-      const selection = queue.shift();
+    // `for...of` also visits the selections pushed to `queue` while iterating
+    for (const selection of queue) {
       if (
         selection.kind === Kind.FRAGMENT_SPREAD &&
         selection.directives?.some((d: DirectiveNode) => d.name.value === 'defer')
@@ -675,7 +675,7 @@ export class ClientSideBaseVisitor<
             this.config.importDocumentNodeExternallyFrom === 'near-operation-file' &&
             this._documents.length === 1
           ) {
-            let documentPath = `./${this.clearExtension(basename(this._documents[0].location))}`;
+            let documentPath = `./${this.clearExtension(basename(this._documents[0].location || ''))}`;
             documentPath += normalizeImportExtension({
               emitLegacyCommonJSImports: this.config.emitLegacyCommonJSImports,
               importExtension: this.config.importExtension,
@@ -692,7 +692,7 @@ export class ClientSideBaseVisitor<
 
             this._imports.add(
               `import * as Operations from '${this.clearExtension(
-                this.config.importDocumentNodeExternallyFrom,
+                this.config.importDocumentNodeExternallyFrom || '',
               )}';`,
             );
           }
@@ -722,7 +722,7 @@ export class ClientSideBaseVisitor<
             importSource: {
               ...fragmentImports[0].importSource,
               identifiers: unique(
-                flatten(fragmentImports.map(fi => fi.importSource.identifiers)),
+                flatten(fragmentImports.map(fi => fi.importSource.identifiers || [])),
                 identifier => identifier.name,
               ),
             },
@@ -747,7 +747,7 @@ export class ClientSideBaseVisitor<
     _operationResultType: string,
     _operationVariablesTypes: string,
     _hasRequiredVariables: boolean,
-  ): string {
+  ): string | null {
     return null;
   }
 

packages/plugins/other/visitor-plugin-common/src/selection-set-processor/base.ts

@@ -14,7 +14,7 @@ export type PrimitiveAliasedFields = {
   fieldName: string;
 };
 export type LinkField = {
-  alias: string;
+  alias?: string;
   name: string;
   type: string;
   selectionSet: string;
@@ -34,7 +34,8 @@ export type SelectionSetProcessorConfig = {
 };
 
 export class BaseSelectionSetProcessor<Config extends SelectionSetProcessorConfig> {
-  typeCache = new Map<Location, Map<string, [string, string]>>();
+  // Keyed by the selection set's `loc`, which is `undefined` for documents parsed with `noLocation`
+  typeCache = new Map<Location | undefined, Map<string, [string, string]>>();
 
   constructor(public config: Config) {}