17429932259

Committed 03 Sep 2025 09:59AM UTC coverage: 81.125% (+0.2%) from 80.965%

Build # 17429932259

Build Type

Pull #502

github

Committed by

web-flow

Commit Message

Merge ed6adc6d6 into 47c0a09e0

Pull Request Pull Request #502: chore: extend library interfaces to allow injecting a custom connection error handler MCP-132

Run Details

901 of 1199 branches covered (75.15%)

Branch coverage included in aggregate %.

92 of 106 new or added lines in 9 files covered. (86.79%)

2 existing lines in 2 files now uncovered.

4579 of 5556 relevant lines covered (82.42%)

44.39 hits per line

Source File
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63.33

/src/transports/stdio.ts

import { EJSON } from "bson";
import type { JSONRPCMessage } from "@modelcontextprotocol/sdk/types.js";
import { JSONRPCMessageSchema } from "@modelcontextprotocol/sdk/types.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { LogId } from "../common/logger.js";
import type { Server } from "../server.js";
import { TransportRunnerBase, type TransportRunnerConfig } from "./base.js";

// This is almost a copy of ReadBuffer from @modelcontextprotocol/sdk
// but it uses EJSON.parse instead of JSON.parse to handle BSON types
export class EJsonReadBuffer {
    private _buffer?: Buffer;

    append(chunk: Buffer): void {
        this._buffer = this._buffer ? Buffer.concat([this._buffer, chunk]) : chunk;
    }

    readMessage(): JSONRPCMessage | null {
        if (!this._buffer) {
            return null;
        }

        const index = this._buffer.indexOf("\n");
        if (index === -1) {
            return null;
        }

        const line = this._buffer.toString("utf8", 0, index).replace(/\r$/, "");
        this._buffer = this._buffer.subarray(index + 1);

        // This is using EJSON.parse instead of JSON.parse to handle BSON types
        return JSONRPCMessageSchema.parse(EJSON.parse(line));
    }

    clear(): void {
        this._buffer = undefined;
    }
}

// This is a hacky workaround for https://github.com/mongodb-js/mongodb-mcp-server/issues/211
// The underlying issue is that StdioServerTransport uses JSON.parse to deserialize
// messages, but that doesn't handle bson types, such as ObjectId when serialized as EJSON.
//
// This function creates a StdioServerTransport and replaces the internal readBuffer with EJsonReadBuffer
// that uses EJson.parse instead.
export function createStdioTransport(): StdioServerTransport {
    const server = new StdioServerTransport();
    server["_readBuffer"] = new EJsonReadBuffer();

    return server;
}

export class StdioRunner extends TransportRunnerBase {
    private server: Server | undefined;

    constructor(config: TransportRunnerConfig) {
        super(config);
    }

    async start(): Promise<void> {
        try {
            this.server = await this.setupServer();

            const transport = createStdioTransport();

            await this.server.connect(transport);
        } catch (error: unknown) {
            this.logger.emergency({
                id: LogId.serverStartFailure,
                context: "server",
                message: `Fatal error running server: ${error as string}`,
            });
            process.exit(1);
        }
    }

    async closeTransport(): Promise<void> {
        await this.server?.close();
    }
}

1	import { EJSON } from "bson";	1!
2	import type { JSONRPCMessage } from "@modelcontextprotocol/sdk/types.js";
3	import { JSONRPCMessageSchema } from "@modelcontextprotocol/sdk/types.js";	1✔
4	import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";	1✔
5	import { LogId } from "../common/logger.js";	1✔
6	import type { Server } from "../server.js";
7	import { TransportRunnerBase, type TransportRunnerConfig } from "./base.js";	1✔
8
9	// This is almost a copy of ReadBuffer from @modelcontextprotocol/sdk
10	// but it uses EJSON.parse instead of JSON.parse to handle BSON types
11	export class EJsonReadBuffer {	1✔
12	private _buffer?: Buffer;
13
14	append(chunk: Buffer): void {	1✔
15	this._buffer = this._buffer ? Buffer.concat([this._buffer, chunk]) : chunk;	1!
16	}	1✔
17
18	readMessage(): JSONRPCMessage \| null {	1✔
19	if (!this._buffer) {	2!
20	return null;	×
21	}	×
22
23	const index = this._buffer.indexOf("\n");	2✔
24	if (index === -1) {	2✔
25	return null;	1✔
26	}	1✔
27
28	const line = this._buffer.toString("utf8", 0, index).replace(/\r$/, "");	1✔
29	this._buffer = this._buffer.subarray(index + 1);	1✔
30
31	// This is using EJSON.parse instead of JSON.parse to handle BSON types
32	return JSONRPCMessageSchema.parse(EJSON.parse(line));	1✔
33	}	2✔
34
35	clear(): void {	1✔
36	this._buffer = undefined;	3✔
37	}	3✔
38	}	1✔
39
40	// This is a hacky workaround for https://github.com/mongodb-js/mongodb-mcp-server/issues/211
41	// The underlying issue is that StdioServerTransport uses JSON.parse to deserialize
42	// messages, but that doesn't handle bson types, such as ObjectId when serialized as EJSON.
43	//
44	// This function creates a StdioServerTransport and replaces the internal readBuffer with EJsonReadBuffer
45	// that uses EJson.parse instead.
46	export function createStdioTransport(): StdioServerTransport {	1✔
47	const server = new StdioServerTransport();	3✔
48	server["_readBuffer"] = new EJsonReadBuffer();	3✔
49
50	return server;	3✔
51	}	3✔
52
53	export class StdioRunner extends TransportRunnerBase {	1✔
54	private server: Server \| undefined;
55
56	constructor(config: TransportRunnerConfig) {	1✔
NEW 57	super(config);	×
UNCOV 58	}	×
59
60	async start(): Promise<void> {	1✔
61	try {	×
62	this.server = await this.setupServer();	×
63
64	const transport = createStdioTransport();	×
65
66	await this.server.connect(transport);	×
67	} catch (error: unknown) {	×
68	this.logger.emergency({	×
69	id: LogId.serverStartFailure,	×
70	context: "server",	×
71	message: `Fatal error running server: ${error as string}`,	×
72	});	×
73	process.exit(1);	×
74	}	×
75	}	×
76
77	async closeTransport(): Promise<void> {	1✔
78	await this.server?.close();	×
79	}	×
80	}	1✔

mongodb-js / mongodb-mcp-server / 17429932259

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