sql_types::Json: Add documentation how to de/serialize to custom type #4798
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weiznich
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Oct 2, 2025
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weiznich
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weiznich
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Thanks for opening this PR.
I think that's a good location to document these things and it's also a good idea to include examples. I left a few remarks on what's potentially broken and causes the CI to fail.
| /// struct Contact { | ||
| /// pub id: i32, | ||
| /// pub name: String, | ||
| /// #[diesel(deserialize_as = serde_json::Value)] |
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This requires an impl TryFrom<serde_json::Value> for Address
| /// # .get_result::<serde_json::Value>(connection)?; | ||
| /// | ||
| /// let santa = contacts.filter(id.eq(1)).first(connection)?; | ||
| /// assert_eq!(santas_address, santda.address); |
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| /// assert_eq!(santas_address, santda.address); | |
| /// assert_eq!(santas_address, santa.address); |
that's likely a typo
| /// }; | ||
| /// | ||
| /// #let inserted_address = insert_into(contacts) | ||
| /// # .values((name.eq("Claus"), address.eq(&santas_address))) |
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For this variant you need to directly convert the address to a serde_json::Value as there is no attribute that's applied.
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Following #4793 (comment), this adds documentation to the
sql_types::Jsontype on how to de/serialize from/to custom types with JSON.Right now this is in draft mode, to get some feedback whether I added the docs in the right location (I believe so, because that's where I'd expect them) and whether the idea of having a code example at that location was the right way of doing this.
What is left to do here:
serialize_aspartjson()function in sqlite to get the desired behaviour out of SQLite (link to the approriate SQLite docs)Into::into()approach for converting from (for example)serde_json::Valueto your custom type when usingdeserialize_asrather thanTryFrom, which might be unexpected (Question for you: Any reason why this isFrom/Intorather thanTryFrom?)CC @weiznich