feat: Add support for using the in operator with context values

This change adds support for the `in` operator when using a context
value in a prisma expression. This allows you to do useful stuff
like allow a match against multiple contextually provided values (e.g.
org membership).

Signed-off-by: Lucian Buzzo <lucian.buzzo@gmail.com>

src/ast-fragments.ts

@@ -0,0 +1,80 @@
+import { escapeLiteral } from "./escape";
+
+/**
+ * Generates an AST fragment that will check if a column value exists in a JSONB array stored in a `current_setting`
+ * The AST fragment represents SQL that looks like this:
+ *  = ANY (SELECT jsonb_array_elements_text(current_setting('ctx.my_context_value')::jsonb))
+ */
+export const jsonb_array_elements_text = (setting: string) => {
+	return {
+		type: "function",
+		name: "ANY",
+		args: {
+			type: "expr_list",
+			value: [
+				{
+					ast: {
+						with: null,
+						type: "select",
+						options: null,
+						distinct: {
+							type: null,
+						},
+						columns: [
+							{
+								type: "expr",
+								expr: {
+									type: "function",
+									name: "jsonb_array_elements_text",
+									args: {
+										type: "expr_list",
+										value: [
+											{
+												type: "cast",
+												keyword: "cast",
+												expr: {
+													type: "function",
+													name: "current_setting",
+													args: {
+														type: "expr_list",
+														value: [
+															{
+																type: "parameter",
+																value: escapeLiteral(setting.replace(/^___yates_context_/, "")),
+															},
+														],
+													},
+												},
+												as: null,
+												symbol: "::",
+												target: {
+													dataType: "jsonb",
+												},
+												arrows: [],
+												properties: [],
+											},
+										],
+									},
+								},
+								as: null,
+							},
+						],
+						into: {
+							position: null,
+						},
+						from: null,
+						where: null,
+						groupby: null,
+						having: null,
+						orderby: null,
+						limit: {
+							seperator: "",
+							value: [],
+						},
+						window: null,
+					},
+				},
+			],
+		},
+	};
+};

src/expressions.ts

@@ -4,6 +4,7 @@ import matches from "lodash/matches";
 import { Parser } from "node-sql-parser";
 import { escapeLiteral } from "./escape";
 import { defineDmmfProperty } from "@prisma/client/runtime/library";
+import { jsonb_array_elements_text } from "./ast-fragments";
 
 // This is black magic to get the runtime data model from the Prisma client
 // It's not exported, so we need to use some type infiltration to get it
@@ -61,6 +62,8 @@ const getDmmfMetaData = (client: PrismaClient, model: string, field: string) =>
 
 // Perform substitution of Ints so that Prisma doesn't throw an error due to mismatched type values
 // After we've captured the SQL, we can replace the Ints with the original values
+// The returned tokens are a map of the token int, and the AST fragment that will replace it.
+// We can then reconstruct the query using the AST fragments.
 const tokenizeWhereExpression = (
 	/** The Prisma client to use for metadata */
 	client: PrismaClient,
@@ -116,6 +119,7 @@ const tokenizeWhereExpression = (
 		const isNumeric = PRISMA_NUMERIC_TYPES.includes(fieldData.type);
 		const isColumnName = typeof value === "string" && !!value.match(/^___yates_row_/);
 		const isContext = typeof value === "string" && !!value.match(/^___yates_context_/);
+		const isInStatement = !!value.in;
 
 		switch (true) {
 			case isColumnName:
@@ -185,6 +189,37 @@ const tokenizeWhereExpression = (
 				};
 				break;
 
+			case isInStatement:
+				if (Array.isArray(value.in)) {
+					const values = [];
+					for (const item in value.in) {
+						values.push({
+							type: "single_quote_string",
+							value: item,
+						});
+					}
+					astFragment = {
+						type: "binary_expr",
+						operator: "IN",
+						left: {
+							type: "column_ref",
+							schema: "public",
+							table: table,
+							column: field,
+						},
+						right: {
+							type: "expr_list",
+							value: values,
+						},
+					};
+				} else {
+					// If the value of `in` is a context value, we assume that it is an array that has been JSON encoded
+					// We create an AST fragment representing a function call to `jsonb_array_elements_text` with the context value as the argument
+					astFragment = jsonb_array_elements_text(value.in);
+				}
+
+				break;
+
 			// All other types are treated as strings
 			default:
 				astFragment = {

src/index.ts

@@ -111,8 +111,17 @@ export const createClient = (prisma: PrismaClient, getContext: GetContextFn, opt
 									`Context variable "${k}" contains invalid characters. Context variables must only contain lowercase letters, numbers, periods and underscores.`,
 								);
 							}
-							if (typeof context[k] !== "number" && typeof context[k] !== "string") {
-								throw new Error(`Context variable "${k}" must be a string or number. Got ${typeof context[k]}`);
+							if (typeof context[k] !== "number" && typeof context[k] !== "string" && !Array.isArray(context[k])) {
+								throw new Error(`Context variable "${k}" must be a string, number or array. Got ${typeof context[k]}`);
+							}
+							if (Array.isArray(context[k])) {
+								for (const v of context[k] as any[]) {
+									if (typeof v !== "string") {
+										throw new Error(`Context variable "${k}" must be an array of strings. Got ${typeof v}`);
+									}
+								}
+								// Cast to a JSON string so that it can be used in RLS expressions
+								context[k] = JSON.stringify(context[k]);
 							}
 						}
 					}

test/integration/expressions.spec.ts

@@ -832,5 +832,82 @@ describe("expressions", () => {
 
 			expect(result2).toBeNull();
 		});
+
+		it("should be able to handle context values that are arrays", async () => {
+			const initial = new PrismaClient();
+
+			const role = `USER_${uuid()}`;
+
+			const testTitle1 = `test_${uuid()}`;
+			const testTitle2 = `test_${uuid()}`;
+
+			const client = await setup({
+				prisma: initial,
+				customAbilities: {
+					Post: {
+						customCreateAbility: {
+							description: "Create posts where there is already a tag label with the same title",
+							operation: "INSERT",
+							expression: (client: PrismaClient, _row, context) => {
+								return client.tag.findFirst({
+									where: {
+										label: {
+											in: context("post.title") as any as string[],
+										},
+									},
+								});
+							},
+						},
+					},
+				},
+				getRoles(abilities) {
+					return {
+						[role]: [abilities.Post.customCreateAbility, abilities.Post.read, abilities.Tag.read, abilities.Tag.create],
+					};
+				},
+				getContext: () => ({
+					role,
+					context: {
+						"post.title": [testTitle1, testTitle2],
+					},
+				}),
+			});
+
+			await expect(
+				client.post.create({
+					data: {
+						title: testTitle1,
+					},
+				}),
+			).rejects.toThrow();
+
+			await client.tag.create({
+				data: {
+					label: testTitle1,
+				},
+			});
+
+			const post1 = await client.post.create({
+				data: {
+					title: testTitle1,
+				},
+			});
+
+			expect(post1.id).toBeDefined();
+
+			await client.tag.create({
+				data: {
+					label: testTitle2,
+				},
+			});
+
+			const post2 = await client.post.create({
+				data: {
+					title: testTitle2,
+				},
+			});
+
+			expect(post2.id).toBeDefined();
+		});
 	});
 });