added to_json function
#4229
added to_json function
#4229
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The last test I am a bit unsure about since trying to parse the returned into JSON into serde_json::Value results in an error |
| /// let result = diesel::select(to_json::<Integer, _>(1)) | ||
| /// .get_result::<Value>(connection)?; | ||
| /// | ||
| /// let expected: Value = serde_json::from_str("1").unwrap(); |
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can we use the serde_json::json! macro instead to construct the expected values?
| /// # Ok(()) | ||
| /// # } | ||
| /// ``` | ||
| fn to_json<E: SingleValue>(e: E) -> Json; |
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This function seems to return null if you pass in a null values. We want to have a doc test demonstrating that this is correctly propagated.
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ive changed the last test a bit, let me know if its okay
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No, that's not what I had in mind. My idea was to make the return type Nullable<Json> if the argument is nullable and Json for non-null arguments. As I did not know without a quick experiment how to do that I've pushed 8089dff to change it. (I needed to try it myself anyway).
To explain what's going on there:
- The
SqlTypetrait as aIsNullassociated type that indicates whether the current type is nullable or not. We can access it as it's a super trait ofSingleValue - The
IsNulltype implementsMaybeNullableType<T>which wrapsTintoNullableif the input type was nullable, otherwise it will just result inT.
By using that as return type we enforce that we return a non-nullable value for non-nullable inputs and nullable types otherwise, which allows us to correctly write the last test case.
added the
to_jsonfunction under #4216