Neo4j Query Builder

A flexible and intuitive query builder for Neo4j and Cypher. Write queries in Rust just as you would write them in Cypher.

Installation

toml neo4j_cypher = { version = "0.2", features=["derive"] }

Usage

Container attributes

• #[cypher(rename = "...")]

  This attribute can be used when in your code you wanted to have the name A, but in Neo4j you wanted to save the structure as a node with name B.

Field attributes

• #[cypher(rename = "...")]

  Rename attribute also can used as s field attribute. The principle of it's operation is similar to that described above. It should be used when you want to automatically change the field name when you build a query with a properties object of Neo4j entity.

• #[cypher(skip)]

  Use this attribute when you what to hide some struct field when you build a query.

• #[cypher(label)]

  You can use such attribute if you want the field value to be used as the label of the node. It is recommended to use enums as a value of such field.

• #[cypher(default)]

  If the field type is some kind of Option<T> you can use this att and when field value will be None, default value for this type will be set.

  Attention: For the type that is used with the simple attribute default, there must be a mandatory implementation of the trait Default

• #[cypher(default = "...")]

  If using a default value for the whole type doesn't work for you, you can use the default value for a one field. The default value should always be specified as a string, but it will be cast to the required type when the query is generated.

Entities

• Node

  Create node:

  rust let node = Node::new("n", "Profile", None, None);

  But you can set derive attribute to the struct #[derive(Debug, Clone, CypQueSet)] and node will be automatically generated!

• Relation

  Create relation:

  ```rust use neo4j_cypher::entity::Relation;

  let rel = Relation::new(a1.node("n1"), a2.node("n2"), "SUBSCRIBE", None); ```

  Where a1 and a2 it's a structs with CypQue derive marco.

Of course, instead of None, you can specify an object of Props or vector of Label.

Templates

toml neo4j_cypher = { version = "...", features=[ "derive", "templates" ] }

Example of a request without using templates

```rust use neo4jcypher::query::matchquery::CompOper;

let query = Query::init().r#match(&a1.node("n1").into(), false) .r#where("name", CompOper::Equal, PropType::str("admin")) .r#match(&a2.node("n2").into(), false) .r#where("name", CompOper::Equal, PropType::str("dev")) .return_many(vec!["n1", "n2"]) .finalize(); ```

Example request with using templates

To include templates, you must add `templates` to the **features** dependency sections.

rust let q = Query::init() .r#match(&a1.node("n1").into(), false) .where_eq_str("name", "admin") .r#match(&a2.node("n2").into(), false) .where_eq_str("name", "dev") .return_many(vec!["n1", "n2"]) .finalize();

Example

Node

```rust use std::fmt::Display;

use neo4jcypher::query::matchquery::CompOper; use neo4j_cypher::CypQue;

/// Example of access levels in the system

[derive(Debug, Clone)]

enum Perm { Admin, User, }

/// An example of a structure that should be converted into a Neo4j node. /// /// In your code you use name Account and the Neo4j node label will be Profile. /// Field username will be renamed; /// Field secret will be hidden; /// Field perm will be used as second a node label; /// Field level and friends will used a default value if they will be None;

[derive(Debug, Clone, CypQue)]

[cypher(rename = "Profile")]

struct Account { #[cypher(rename = "name")] username: String, password: String, age: i32, status: Option, online: bool, #[cypher(skip)] secret: u8, #[cypher(label)] perm: Perm, #[cypher(default = "5")] level: Option, #[cypher(default = "['Bob', 'Tom']")] friends: Option>, }

fn main() { // Init some example struct let data = Account { username: String::from("mi1fhunter"), password: String::from("1234f4321"), age: 32, status: None, online: false, secret: 1, perm: Perm::User, level: None, friends: Some(vec![ "Bob".tostring(), "Tom".tostring(), "Sam".to_string(), ]), };

// Let's build some query
let query = Query::init()
    .create(vec![&a1.node("n").into()])
    .r#return("n")
    .finalize();

println!("{}", query);

} ```

So, the query builder automatically generated such query for you:

sql CREATE (n:Profile { password: '1234f4321',level: 5,name: 'mi1fhunter',age: 32,friends: ['Bob','Tom','Sam'],online: false }) SET n:User RETURN n

Example of creating a match query:

rust let query = Query::init() .r#match(&a1.node("n1").into(), false) .where_eq_str("name", "admin") .r#match(&a2.node("n2").into(), false) .where_eq_str("name", "dev") .return_many(vec!["n1", "n2"]) .finalize();

The result will be like this:

sql MATCH (n1:Profile) WHERE n1.name = 'admin' MATCH (n2:Profile) WHERE n2.name = 'dev' RETURN n1,n2

If you need to return the value of some propertie or get another var name, you can write it like this:

rust let query = Query::init() .create(vec![&model.node("n").into()]) .r#return_field("n", "age") .finalize();

The result will be:

sql CREATE (n:Profile { name: 'admin',friends: ['Bob','Tom','Sam'],password: '1234f4321',online: false,level: 5,age: 32 }) SET n:User RETURN n.age

OR

rust let query = Query::init() .create(vec![&model.node("n").into()]) .r#return("n") .r#as("node") .finalize();

Result:

sql CREATE (n:Profile { age: 32,uname: 'mi1fhunter',online: false,level: 5,friends: ['Bob','Tom','Sam'],password: '1234f4321' }) SET n:User RETURN n AS node

Relation

```rust let rel1 = Entity::rel("n1", "n2", "SUBSCRIBE", None); let rel2 = Entity::rel("n2", "n1", "SUBSCRIBE", None);

let query = Query::init() .r#match(&a1.node("n1").into(), false) .whereeqstr("name", "admin") .r#match(&a2.node("n2").into(), false) .whereeqstr("name", "dev") .return_many(vec!["n1", "n2"]) .create(vec![&rel1.into(), &rel2.into()]) .finalize(); ```

Result:

sql MATCH (n1:Profile) WHERE n1.age = 1 AND n1.level = 10 MATCH (n1:Profile) WHERE n1.age = 10 CREATE (n1)-[:SUBSCRIBE]->(n2), (n2)-[:SUBSCRIBE]->(n1)