1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
# The `rfl::Field`-syntax
As we have shown, reflect-cpp can automatically retrieve field names from structs.
However, it also possible to annotate the fields using `rfl::Field`, like this:
```cpp
struct Person {
rfl::Field<"firstName", std::string> first_name;
rfl::Field<"lastName", std::string> last_name;
rfl::Field<"children", std::vector<Person>> children;
};
```
These annotations are required if you are planning to use a compiler other than MSVC, GCC or clang.
There are a two things you have to keep in mind:
1) If you annotate *some* of the fields using `rfl::Field`, then you must annotate *all* of them.
2) If you are combining structs using `rfl::Flatten`, then they structs combined like this must either be annotated or not.
You can initilize your struct like this:
```cpp
const auto bart = Person{.first_name = "Bart",
.last_name = "Simpson",
.children = std::vector<Person>()};
```
Note that all fields must be explicitly set. This is on purpose, because it prevents you from accidentally forgetting fields,
which can lead to tricky runtime errors.
You can initialize a field using `rfl::default_value`:
```cpp
const auto bart = Person{.first_name = "Bart",
.last_name = "Simpson",
.children = rfl::default_value};
```
You can also initialize fields in the struct declaration itself:
```cpp
struct Person {
rfl::Field<"firstName", std::string> first_name;
rfl::Field<"lastName", std::string> last_name = "Simpson";
rfl::Field<"children", std::vector<Person>> children = rfl::default_value;
};
```
Because you now have explicitly set those fields, you do not have to do this every time:
```cpp
const auto bart = Person{.first_name = "Bart"};
const auto lisa = Person{.first_name = "Lisa"};
const auto maggie = Person{.first_name = "Maggie"};
const auto homer = Person{.first_name = "Homer",
.children = std::vector<Person>({bart, lisa, maggie})};
```
You can write this to a JSON string:
```cpp
const auto json_string = rfl::json::write(homer);
```
```json
{"firstName":"Homer","lastName":"Simpson","children":[{"firstName":"Bart","lastName":"Simpson","children":[]},{"firstName":"Lisa","lastName":"Simpson","children":[]},{"firstName":"Maggie","lastName":"Simpson","children":[]}]}
```
And you can parse it back into a struct:
```cpp
const auto homer = rfl::json::read<Person>(json_string).value();
```
|
