---
title: "Chat Completions API"
description: "Minimal request, common fields, reading responses, and multi-turn conversation usage for POST /v1/chat/completions."
headingIds: {"Minimal Request":"section-1","Common Fields":"section-2","How to Read the Response":"section-3","Multi-Turn Conversation":"section-4","Streaming and Next Steps":"section-5"}
---

<aside className="docs-publication" data-pagefind-ignore>

Documentation maintained by [1ZheAI](https://1zheai.com/en/editorial/#publisher). [Sources and corrections](https://1zheai.com/en/editorial/).

Found an error? [Contact support](mailto:support@1zheai.com) with the page address and a description. Do not send API keys or account credentials.

</aside>
Start with this endpoint when using an OpenAI-compatible client, or when you already have `chat.completions.create` code. The full address is `https://1zheai.com/v1/chat/completions`; for SDKs, fill in the Base URL only up to `/v1`.

## Minimal Request

First set `ONEZHE_API_KEY` in your terminal to this site's API key. The model below must exist in [your available model list ](/en/docs/api-models/).

```bash
curl --fail-with-body --connect-timeout 10 --max-time 120 \
  https://1zheai.com/v1/chat/completions \
  -H "Authorization: Bearer $ONEZHE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.6-sol",
    "messages": [{"role": "user", "content": "请用一句中文解释 DNS 的作用。"}]
  }'
```

`--fail-with-body` makes HTTP errors return a non-zero exit code while preserving the error body; requires curl 7.76 or later. On older versions, use `-i` first to view the status code.

## Common Fields

| Field | Type | Usage |
| --- | --- | --- |
| `model` | string | Required. Copy this site's model ID; do not add vendor prefixes from other platforms. |
| `messages` | array | Required. Send this round's question and the history messages to retain, in order. |
| `messages[].role` | string | For normal conversation use `user` / `assistant`; support for the system instruction role depends on the model. |
| `messages[].content` | string or content block array | Use a string for plain text first; image input requires the model to support the corresponding content block. |
| `stream` | boolean | When set to `true`, read SSE instead of treating the entire response as a single JSON. |
| `temperature` | number | Optional; some reasoning models do not support modifying it. Omit it first, then verify item by item. |
| `tools` / `tool_choice` | array / string or object | Optional; both the model and upstream must support them. Actual tool execution is performed by your program. |

Output limit parameters vary by model. Do not mechanically swap Claude's `max_tokens`, Responses' `max_output_tokens`, and Chat Completions parameters; refer to the selected model's requirements, and on a 400 error check the error body first.

## How to Read the Response

The plain text result is located at `choices[0].message.content`. The finish reason is at `choices[0].finish_reason`; when tool calls are returned, the text may be empty and you need to read `message.tool_calls`. The response's `id`, `model`, and `usage` can be used to verify this call.

Below only shows the structure you need to pay attention to; omitted fields and numbers do not represent actual request results:

```json
{
  "id": "example-completion",
  "object": "chat.completion",
  "model": "gpt-5.6-sol",
  "choices": [{
    "index": 0,
    "message": {"role": "assistant", "content": "DNS 将域名解析为网络地址。"},
    "finish_reason": "stop"
  }]
}
```

## Multi-Turn Conversation

The endpoint does not automatically remember the previous round just because you reuse the same API key. Send the history you want to retain together:

```json
{
  "model": "gpt-5.6-sol",
  "messages": [
    {"role": "user", "content": "我正在学习 DNS。"},
    {"role": "assistant", "content": "我们可以从域名解析开始。"},
    {"role": "user", "content": "它和 HTTP 有什么区别？"}
  ]
}
```

The longer the history, the larger the request. Applications should trim or summarize according to context limits, and keep complete tool call and result pairs.

## Streaming and Next Steps

After adding `"stream": true`, text deltas come from `choices[].delta.content`. Some events have no text or `choices` is empty, so you must check when reading; see [Streaming Output ](/en/docs/streaming/) for details.

Run the [Python / Node.js full example ](/en/docs/code-examples/) directly, or switch to [Responses ](/en/docs/api-responses/); for Claude native parameters see [Messages ](/en/docs/api-messages/).