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nlohmann
88 lines
2.6 KiB
Markdown
88 lines
2.6 KiB
Markdown
# nlohmann::basic_json::object
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```
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static basic_json object(initializer_list_t init = {});
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```
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Creates a JSON object value from a given initializer list. The initializer lists elements must be pairs, and their first elements must be strings. If the initializer list is empty, the empty object `{}` is created.
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## Parameters
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`init` (in) : initializer list with JSON values to create an object from (optional)
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## Return value
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JSON object value
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## Exception safety
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Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
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## Exceptions
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Throws [`type_error.301`](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error301) if `init` is not a list of pairs whose first elements are strings. In this case, no object can be created. When such a value is passed to `basic_json(initializer_list_t, bool, value_t)`, an array would have been created from the passed initializer list `init`. See the example below.
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## Complexity
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Linear in the size of `init`.
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## Notes
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This function is only added for symmetry reasons. In contrast to the related function `array(initializer_list_t)`, there are no cases that can only be expressed by this function. That is, any initializer list `init` can also be passed to the initializer list constructor `basic_json(initializer_list_t, bool, value_t)`.
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## Examples
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Example
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The following code shows an example for the `object` function.
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```
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#include <iostream>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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int main()
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{
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// create JSON objects
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json j_no_init_list = json::object();
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json j_empty_init_list = json::object({});
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json j_list_of_pairs = json::object({ {"one", 1}, {"two", 2} });
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// serialize the JSON objects
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std::cout << j_no_init_list << '\n';
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std::cout << j_empty_init_list << '\n';
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std::cout << j_list_of_pairs << '\n';
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// example for an exception
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try
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{
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// can only create an object from a list of pairs
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json j_invalid_object = json::object({{ "one", 1, 2 }});
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}
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catch (const json::type_error& e)
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{
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std::cout << e.what() << '\n';
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}
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}
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```
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Output:
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```
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{}
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{}
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{"one":1,"two":2}
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[json.exception.type_error.301] cannot create object from initializer list
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```
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## See also
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- [`basic_json(initializer_list_t)`](https://json.nlohmann.me/api/basic_json/basic_json/index.md) - create a JSON value from an initializer list
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- [`array`](https://json.nlohmann.me/api/basic_json/array/index.md) - create a JSON array value from an initializer list
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- [Creating JSON values](https://json.nlohmann.me/features/creating_values/index.md) - the article on creating JSON values
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## Version history
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- Added in version 1.0.0.
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