Surreal simple querybuilder

A simple query-builder for the Surreal Query Language, for SurrealDB. Aims at being simple to use and not too verbose first.

Summary

Why a query-builder

Query builders allow you to dynamically build your queries with some compile time checks to ensure they result in valid SQL queries. Unlike ORMs, query-builders are built to be lightweight and easy to use, meaning you decide when and where to use one. You could stick to hard coded string for the simple queries but use a builder for complex ones that require parameters & variables and may change based on these variables for example.

While the crate is first meant as a query-building utility, it also comes with macros and generic types that may help you while managing you SQL models in your rust code. Refer to the node macro and the Foreign type example

SQL injections

The strings you pass to the query builder are not sanitized in any way. Please use parameters in your queries like SET username = $username with surrealdb parameters to avoid injection issues. However the crate comes with utility functions to easily create parameterized fields, refer to the NodeBuilder trait.

Compiler requirements/features

The crate uses const expressions for its model creation macros in order to use stack based arrays with sizes deduced by the compiler. For this reason any program using the crate has to add the following at the root of the main file: ```

![allow(incomplete_features)]

![feature(genericconstexprs)]

```

Examples

Keep in mind all of the demonstrated features can be used independently of the rest. They can all be combined if you want to, but if you prefer a lightweight solution then it is possible as well.

By default only the querybuilder is available, other modules require you to enable their respective crate features.

Premade queries with dynamic parameters (queries feature)

The crate offers a set of premade queries you can access in surreal_simple_querybuilder::queries::*; or in the prelude for easier access. ```rust use surrealsimplequerybuilder::prelude::*;

fn main() { let (query, _bindings) = select("*", "user", ());

assert_eq!(query, "SELECT * FROM user"); } ```

these pre-made query functions accept all types of parameters to further extend the queries. If dynamic values (variables) are passed among these parameters then the functions will automatically add them to the list of bindings: ```rust use surrealsimplequerybuilder::prelude::*; use serde_json::json;

fn main() { let (query, bindings) = select("*", "user", Where(json!({ "name": "John" })));

assert_eq!(query, "SELECT * FROM user WHERE name = $name");

// 👇 the bindings were updated with the $name variable asserteq!(bindings.get("name"), Some("John".toowned())); } ```

Why dynamic parameters

At a first glance these pre-made queries offer nothing the querybuilder doesn't, but in reality they allow you to easily make functions in your backends (for example) that you can extend if need be.

The first scenario that comes to mind is a standard function to retrieve books by the author: rust impl Book { fn find_by_author_id(id: &str) -> Vec<Self> { // ... } }

In some cases you'll need the list of books and nothing else, another time you'll need the results to be paginated, and sometimes you'll want to fetch the author data on top of the books. Considering you may also want to have the books with both pagination and fetch this could potentially result in at least 4 different functions & queries to write.

With the dynamic parameters you can update your find function to accept optional parameters so that only 1 simple function is needed:

```rust use serde_json::json;

impl Book { fn findbyauthorid<'a>(id: &str, params: impl QueryBuilderInjecter<'a> + 'a) -> Vec { let filter = Where(json!({"author": id})); let combinedparams = (filter, params);

let (query, params) = select("*", "Book", combined_params).unwrap();

DB.query(query)
  .bind(params)
  .await.unwrap()
  .get(..).unwrap()

} } So you can now do: rust let books = Book::findbyauthorid("User:john", ()); let paginatedbooks = Book::findbyauthorid("User:john", Pagination(0..25)); let paginatedbookswithauthordata = Book::findbyauthorid( "User:john", ( Pagination(0..25), Fetch(["author"]) ) ); ```

The dynamic parameters & premade queries are made with the model macro in mind, you don't necessarily need it but if you wanted, both systems can be used for some compile time checks + dynamic parameters to enjoy the extra freedom dynamic parameters provide while being sure all of the fields & nodes you reference in them are valid thanks to the models. A complete example on how to combine both system is available here.

Limitations & recommandations for premade queries & params

The short example and complete test case demonstrate the premade queries can work in 99% of the cases and can seriously simplify the code you write. However there are limitations one must be aware of before going too deep into the premade queries.

The premade queries and composable parameters are made for those simple cases where you just want to select/create/etc... elements without complex filtering in the WHERE clause or anything. For example selecting books by one of their field is perfect for the premade queries as you can add a fetch clause without having to rewrite anything. It allows you to have somewhat generic functions in your codebase for the simple cases.

But as soon as it gets complex, the QueryBuilder type should be used instead of the pre-made queries. It will offer both better performances & more predictable results (nesting lots of params may yield unexpected queries). Note that you can still use a query-builder and pass it params (aka injecters) if need: ```rust use surrealsimplequerybuilder::prelude::*;

let params = ( Where(("name", "john")), Fetch(["articles"]) );

let query = QueryBuilder::new() .select("*") .from("user") .injecter(&params) // <-- pass the injecter to the builder .build();

let _params = bindings(params); // <-- get the variables so you can bind them

assert(query, "SELECT * FROM user WHERE name = $name FETCH articles"); ```

And as you can see, even in the more complex cases the params can still be used but the pre-made queries should not however.

The model macro (model feature)

The model macro allows you to quickly create structs (aka models) with fields that match the nodes of your database.

example

```rust use surrealsimplequerybuilder::prelude::*;

struct Account { id: Option, handle: String, password: String, email: String, friends: Foreign> }

model!(Account { id, handle, password, friends> });

fn main() { // the schema module is created by the macro use schema::model as account;

let query = format!("select {} from {account}", account.handle);
assert_eq!("select handle from Account", query);

} ```

This allows you to have compile time checked constants for your fields, allowing you to reference them while building your queries without fearing of making a typo or using a field you renamed long time ago.

public & private fields in models

The QueryBuilder type offers a series of methods to quickly list the fields of your models in SET or UPDATE statements so you don't have to write the fields and the variable names one by one. Since you may not want to serialize some of the fields like the id for example the model macro has the pub keyword to mark a field as serializable. Any field without the pub keyword in front of it will not be serialized by these methods.

```rust model!(Project { id, // <- won't be serialized pub name, // <- will be serialized })

fn example() { use schema::model as project;

let query = QueryBuilder::new() .set_model(project) .build();

assert_eq!(query, "SET name = $name"); } ```

Relations between your models

If you wish to include relations (aka edges) in your models, the model macro has a special syntax for them:

```rust mod account { use surrealsimplequerybuilder::prelude::*; use super::project::schema::Project;

model!(Account { id,

->manage->Project as managed_projects

}); }

mod project { use surrealsimplequerybuilder::prelude::*; use super::project::schema::Project;

model!(Project { id, name,

<-manage<-Account as authors

}); }

fn main() { use account::schema::model as account;

let query = format!("select {} from {account}", account.managed_projects);
assert_eq!("select ->manage->Project from Account");

let query = format!("select {} from {account}", account.managed_projects().name.as_alias("project_names"))
assert_eq!("select ->manage->Project.name as project_names from Account", query);

} ```

The NodeBuilder traits (querybuilder feature)

These traits add a few utility functions to the String and str types that can be used alongside the querybuilder for even more flexibility.

```rust use surrealsimplequerybuilder::prelude::*;

let mylabel = "John".asnamedlabel("Account"); asserteq!("Account:John", &my_label);

let myrelation = mylabel .with("FRIEND") .with("Mark".asnamedlabel("Account"));

asserteq!("Account:John->FRIEND->Account:Mark", myrelation); ```

The QueryBuilder type (querybuilder feature)

It allows you to dynamically build complex or simple queries out of segments and easy to use methods.

Simple example

```rust use surrealsimplequerybuilder::prelude::*;

let query = QueryBuilder::new() .select("*") .from("Account") .build();

assert_eq!("SELECT * FROM Account", &query); ```

Complex example

```rust use surrealsimplequerybuilder::prelude::*;

let shouldfetchauthors = false; let query = QueryBuilder::new() .select("*") .from("File") .ifthen(shouldfetch_authors, |q| q.fetch("author")) .build();

assert_eq!("SELECT * FROM Account", &query);

let shouldfetchauthors = true; let query = QueryBuilder::new() .select("*") .from("File") .ifthen(shouldfetch_authors, |q| q.fetch("author")) .build();

assert_eq!("SELECT * FROM Account FETCH author", &query); ```

The ForeignKey and Foreign types (foreign feature)

SurrealDB has the ability to fetch the data out of foreign keys. For example: ```sql create Author:JussiAdlerOlsen set name = "Jussi Adler-Olsen"; create File set name = "Journal 64", author = Author:JussiAdlerOlsen;

select * from File; select * from File fetch author; which gives us json // without FETCH author { "author": "Author:JussiAdlerOlsen", "id":"File:rg30uybsmrhsf7o6guvi", "name":"Journal 64" }

// with FETCH author { "author": { "id":"Author:JussiAdlerOlsen", "name":"Jussi Adler-Olsen" }, "id":"File:rg30uybsmrhsf7o6guvi", "name":"Journal 64" } ```

The "issue" with this functionality is that our results may either contain an ID to the author, no value, or the fully fetched author with its data depending on the query and whether it includes fetch or not.

The ForeignKey types comes to the rescue. It is an enum with 3 variants: - The loaded data for when it was fetched - The key data for when it was just an ID - The unloaded data when it was null (if you wish to support missing data you must use the #serde(default) attribute to the field)

The type comes with an implementation of the Deserialize and Serialize serde traits so that it can fallback to whatever data it finds or needs. However any type that is referenced by a ForeignKey must implement the IntoKey trait that allows it to safely serialize it into an ID during serialization.

example

```rust /// For the tests, and as an example we are creating what could be an Account in /// a simple database. #[derive(Debug, Serialize, Deserialize, Default)] struct Account { id: Option, handle: String, password: String, email: String, }

impl IntoKey for Account { fn intokey(&self) -> Result where E: serde::ser::Error, { self .id .asref() .map(String::clone) .ok_or(serde::ser::Error::custom("The account has no ID")) } }

#[derive(Debug, Serialize, Deserialize)] struct File { name: String,

/// And now we can set the field as a Foreign node
author: Foreign<Account>,

}

fn main() { // ...imagine query is a function to send a query and get the first result... let file: File = query("SELECT * from File FETCH author");

if let Some(user) = file.author.value() {
  // the file had an author and it was loaded
  dbg!(&user);
}

// now we could also support cases where we do not want to fetch the authors
// for performance reasons...
let file: File = query("SELECT * from File");

if let Some(user_id) = file.author.key() {
  // the file had an author ID, but it wasn't fetched
  dbg!(&user_id);
}

// we can also handle the cases where the field was missing
if file.author.is_unloaded {
  panic!("Author missing in file {file}");
}

} ```

ForeignKey and loaded data during serialization

A ForeignKey always tries to serialize itself into an ID by default. Meaning that if the foreign-key holds a value and not an ID, it will call the IntoKey trait on the value in order to get an ID to serialize.

There are cases where this may pose a problem, for example in an API where you wish to serialize a struct with ForeignKey fields so the users can get all the data they need in a single request.

By default if you were to serialize a File (from the example above) struct with a fetched author, it would automatically be converted into the author's id.

The ForeignKey struct offers two methods to control this behaviour: ``rust // ...imaginequery` is a function to send a query and get the first result... let file: File = query("SELECT * from File FETCH author");

file.author.allowvalueserialize();

// ... serializing file will now serialize its author field as-is.

// to go back to the default behaviour file.author.disallowvalueserialize(); ```

You may note that mutability is not needed, the methods use interior mutability to work even on immutable ForeignKeys if needed.

Using the querybuilder in combination of the official SurrealDB client

There is an important thing to keep in mind with this querybuilding crate, it is meant to serve as an utility crate that is completely independant of the client you use. For this reason it does not offer anything to send the queries and getting the responses directly but since you'll rarely want to use this crate without a client one of the test cases demonstrates how to write create, select, update functions that would connect the querybuilder to the official surrealdb client.

While it is not convenient to have to write these functions yourself it allows you to use a fixed version of the querybuilder crate while still getting the latest breaking updates on your favorite client.

Here is a link to the file, the functions are created in the part 1 section. And here are snippets of what the functions allow you to do: ```rust update(book_id, Set((book.read, true))).await?;

let allbooks: Vec = select(&book, ()).await?; let user0books: Vec = select(&book, Where((book.author, user0_id))).await?;

let bookswithauthor: Vec = select( &book, ( Where((book.author, user1id)), Fetch([book.author.asref()]), ), ) .await?; ```