impl Serialize for Tweet/TwitterUser #99
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the idea behind the macro is that i want the Deserialize impl to work either with the original Twitter JSON, *or* with the serialization output from the derived Serialize impl. Since i can't attempt an automatic serialization directly into Tweet as-is (it would try to read it as Twitter's JSON) i decided to make a copy of the struct definition and provide a transparent From impl for easy conversion. combine this with an enum labeled with `#[serde(untagged)]` and serde will do the "try either of these" logic for me! i had to leave out Place and User because they had complicated serialization logic that i wanted to parcel out to other commits (and in User's case, since it also contains a Tweet, i would have to apply Serialize to both of them at the same time for it to "fully" work).
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I had an idea about the error-message problem and posted a new commit. It adds two new functions to types that deserialize via |
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Some review notes to self while reading this over, two weeks later:
- refactor idea: turn the error-reporting methods into a trait so i can write docs on how to pull a deser error?
- even if i don't move the deserialization-error functions, i really want more docs somewhere to describe what you can do if something fails to load. i could throw something on the impl block, but that would either mean having the same sample on both tweets and users (which is awkward), or extending the macro to take in that sample (which is more awkward). at least in a trait i can either put multiple samples, or just say "this is for users, but tweets would work the same". 🤷♀️
- i'd love to have some way to default the
serde(untagged)error message to one of the variants (in this case the raw struct), but that's not a thing :/
src/common/mod.rs
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| where | ||
| S: Serializer, | ||
| { | ||
| ser.collect_str(&src.format("%a %b %d %T %z %Y")) |
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tiny nit: might as well combine this date format string into a const
src/place/mod.rs
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| @@ -367,3 +368,39 @@ where | |||
| serde_json::from_value::<Vec<(f64, f64)>>(inner_arr).map_err(|e| D::Error::custom(e)) | |||
| }) | |||
| } | |||
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| fn serialize_bounding_box<S>(src: &Vec<(f64, f64)>, ser: S) -> Result<S::Ok, S::Error> | |||
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nit: should this combine (de)serialize_bounding_box into a single serialize module so you can combine the serde attributes into a single #[serde(with)]? probably, yeah
src/tweet/raw.rs
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| @@ -2,15 +2,17 @@ use crate::{place, user}; | |||
| use chrono; | |||
| use serde::Deserialize; | |||
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| use crate::common::{serde_datetime}; | |||
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should probably trim the brackets here
Closes #90
This PR adds a
Serializeimpl for various types in the library, most notablyTweetandTwitterUser. Since those types have existingDeserializeimpls that load via a "raw" type that mirrors Twitter's JSON representation, i needed to introduce a new mechanism to allow loading via either Twitter's JSON or egg-mode's.The way i did this for this PR was to introduce a new
round_trip!macro that wrapped the structs and added some new items used internally by the macro:SerCopy, a field-for-field copy of the given type,SerEnum, an enum which can either be the "raw" type orSerCopy,Deserializeimplementations that leverage the#[serde(untagged)]attribute to drive the deserialization.One major drawback with this approach is that if the "raw" type gets out-of-sync with Twitter's representation, the only error message you see is
"data did not match any variant of untagged enum SerEnum", instead of knowing which field is missing. On the other hand, doing it this way means that there is no overhead of doing the deserialization manually (anyone remember the originalFromJsonimpls?) or loading the whole response into aserde_json::Valuefirst. I'm posting this provisionally to see if this suits people's purposes, and to ask whether this should wrap other public types in egg-mode.