http-dynamodb example #562
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Hello Thanks for all the useful comment. I have attempted to implement all of the requested changes. In the end, I created two Item structs using serde, one that gets sent to Dynamo and one that is sent back to the user. I doubt this is the correct way. However, add_item requires ownership of the struct and with serde (serialize , deserialize) I could not figure out a way to implement the Copy or Move trait.. The compiler was not allowing me to reuse Item to return to the user as it had been changed.. So, I implemented this hack instead. I would also like to return a 400 error if the rest call made by the user is missing parameters.. Now the function crashes and returns a 500. Any ideas how to do this ? I see examples that you wrote in how to return errors.. But I can't figure out how to determine when serde realizes the request is missing a field and to return the missing field(s) back to the user.. Thanks.. getting there. |
examples/http-dynamodb/src/main.rs
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| pub async fn add_item(client: &Client, item: Item, table: &String) -> Result<(), OtherError> { | ||
| let user_av = AttributeValue::S(item.username); | ||
| pub async fn add_item(client: &Client, item: Item, table: &str) -> Result<(), OtherError> | ||
| { let user_av = AttributeValue::S(item.username); |
examples/http-dynamodb/src/main.rs
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| //Serialize the data into the struct. | ||
| let item: Item = serde_json::from_str(s).map_err(Box::new)?; | ||
| //Create a copy to send back via the Response. | ||
| let copy_item: Item = serde_json::from_str(s).map_err(Box::new)?; |
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since you're basically cloning the struct, it might be better to add Clone to the structure's derive attributes, and use item.clone() when you call add_item.
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Code was formatted. |
examples/http-dynamodb/src/main.rs
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| use aws_sdk_dynamodb::model::AttributeValue; | ||
| use aws_sdk_dynamodb::{Client, Error as OtherError}; | ||
| use lambda_http::{run, service_fn, Error, IntoResponse, Request}; | ||
| use tracing::info; | ||
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| #[derive(serde::Deserialize, serde::Serialize)] |
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add
| #[derive(serde::Deserialize, serde::Serialize)] | |
| #[derive(Clone, serde::Deserialize, serde::Serialize)] |
examples/http-dynamodb/src/main.rs
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| impl Clone for Item { | ||
| fn clone(&self) -> Item { | ||
| return Item { | ||
| p_type: self.p_type.clone(), | ||
| age: self.age.clone(), | ||
| username: self.username.clone(), | ||
| first: self.first.clone(), | ||
| last: self.last.clone(), | ||
| }; | ||
| } | ||
| } |
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I don't think you need this if you add the derive to the struct.
| impl Clone for Item { | |
| fn clone(&self) -> Item { | |
| return Item { | |
| p_type: self.p_type.clone(), | |
| age: self.age.clone(), | |
| username: self.username.clone(), | |
| first: self.first.clone(), | |
| last: self.last.clone(), | |
| }; | |
| } | |
| } |
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Thanks. I had tried adding Clone to derive, and the compiler wasn't having it.. I thought maybe serde was somehow blocking Clone.. but it looks like I just had the syntax wrong. ;-) I've made the change. There is one last thing, should I be checking if the input request is correctly formatted and missing fields ? Right now, if you send a request with a missing field, the function crashes and returns a 500. I can see how to return an error from your examples, but I can't figure out how to pull out the errors from serde when calling let item: Item = serde_json::from_str(s).map_err(Box::new)?; |
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Check if JSON is valid. If not, return 400 and abort. |
Issue #, if available:
This is an example of a rust lambda function that takes in a JSON payload and writes to a Dynamodb table.
Description of changes:
First commit.
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