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37 lines
1.4 KiB
Markdown
37 lines
1.4 KiB
Markdown
---
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title: "C02. Send and Receive JSON"
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order: 2
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status: "draft"
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---
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cpp-httplib doesn't include a JSON parser. Use a library like [nlohmann/json](https://github.com/nlohmann/json) to build and parse JSON. The examples here use `nlohmann/json`.
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## Send JSON
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```cpp
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httplib::Client cli("http://localhost:8080");
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nlohmann::json j = {{"name", "Alice"}, {"age", 30}};
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auto res = cli.Post("/api/users", j.dump(), "application/json");
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```
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Pass the JSON string as the second argument to `Post()` and the Content-Type as the third. The same pattern works with `Put()` and `Patch()`.
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> **Warning:** If you omit the Content-Type (the third argument), the server may not recognize the body as JSON. Always specify `"application/json"`.
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## Receive a JSON response
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```cpp
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auto res = cli.Get("/api/users/1");
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if (res && res->status == 200) {
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auto j = nlohmann::json::parse(res->body);
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std::cout << j["name"] << std::endl;
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}
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```
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`res->body` is a `std::string`, so you can pass it straight to your JSON library.
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> **Note:** Servers sometimes return HTML on errors. Check the status code before parsing to be safe. Some APIs also require an `Accept: application/json` header. If you're calling a JSON API repeatedly, [C03. Set default headers](../c03-default-headers) can save you some boilerplate.
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> For how to receive and return JSON on the server side, see [S02. Receive JSON requests and return JSON responses](../s02-json-api).
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