Crate memquery[−][src]
MemQuery
MemQuery is simple library for creating, querying, and updating in memory documents that are represented as JSON objects and queried using Mongodb like operators.
This is not a database and it is not trying to do any optimizations. It is meant for unit tests or simple projects that require small in memory document store.
The library uses async API that support tokio. The library also has a sync API that may be enabled via sync
feature flag.
Example Usage
Create Database
use memquery::{errors::Error, memdb::MemDb}; let memdb = MemDb::new();
Create Collection
use memquery::{errors::Error, memdb::MemDb}; let memdb = MemDb::new(); memdb.create_collection("TestCollection").await;
Get Collection Handle
use memquery::{errors::Error, memdb::MemDb}; let coll = memdb.collection("TestCollection").await?;
Insert Document
use memquery::{errors::Error, memdb::MemDb, doc}; let coll = memdb.collection("TestCollection").await?; coll.insert(doc!({ "name": "Tom", "age": 25 })).await?;
Find Document
use memquery::{errors::Error, memdb::MemDb, doc, query}; let coll = memdb.collection("TestCollection").await?; coll.insert(doc!({ "name": "Tom", "age": 25 })).await?; let docs = coll.find(query!({"name": "Tom", "age": 25})).await?;
Logical Query Operators
$and
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll .find(query!({ "$and": [{ "name": "Bob" }, { "age": 20 }] })) .await?;
$or
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll .find(query!({ "$or": [{ "name": "Bob" }, { "age": 30 }] })) .await?;
Comparison Query Operators
$eq
Compare on field:
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "qty": { "$eq": 20 } })).await?;
Or in embedded document:
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "item.name": { "$eq": "ab" } })).await?;
You can also compare array with embedded arrays:
use memquery::{errors::Error, memdb::MemDb, doc, query}; coll .insert(doc!({ "item": { "name": "ab", "code": "123" }, "qty": 15, "tags": [ "A", "B", "C" ] })) .await?; coll .insert(doc!({ "item": { "name": "cd", "code": "123" }, "qty": 20, "tags": [ "B" ] })) .await?; coll .insert(doc!({ "item": { "name": "ij", "code": "456" }, "qty": 25, "tags": [ "A", "B" ] })) .await?; coll .insert(doc!({ "item": { "name": "xy", "code": "456" }, "qty": 30, "tags": [ "B", "A" ] })) .await?; coll .insert( doc!({ "item": { "name": "mn", "code": "000" }, "qty": 20, "tags": [ [ "A", "B" ], "C" ] }), ) .await?; let docs = coll .find(query!({ "tags": { "$eq": [ "A", "B" ] } })) .await?; assert_eq!(docs.len(), 2); assert_eq!(docs[0]["item"]["name"], "ij"); assert_eq!(docs[1]["item"]["name"], "mn");
Or value in the embedded array:
use memquery::{errors::Error, memdb::MemDb, doc, query}; coll .insert(doc!({ "item": { "name": "ab", "code": "123" }, "qty": 15, "tags": [ "A", "B", "C" ] })) .await?; coll .insert(doc!({ "item": { "name": "cd", "code": "123" }, "qty": 20, "tags": [ "B" ] })) .await?; coll .insert(doc!({ "item": { "name": "ij", "code": "456" }, "qty": 25, "tags": [ "A", "B" ] })) .await?; coll .insert(doc!({ "item": { "name": "xy", "code": "456" }, "qty": 30, "tags": [ "B", "A" ] })) .await?; coll .insert( doc!({ "item": { "name": "mn", "code": "000" }, "qty": 20, "tags": [ [ "A", "B" ], "C" ] }), ) .await?; let docs = coll.find(query!({ "tags": { "$eq": "B" } })).await?; assert_eq!(docs.len(), 4); assert_eq!(docs[0]["item"]["name"], "ab"); assert_eq!(docs[1]["item"]["name"], "cd"); assert_eq!(docs[2]["item"]["name"], "ij"); assert_eq!(docs[3]["item"]["name"], "xy");
$gt
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "qty": { "$gt": 20 } })).await?;
$gte
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "qty": { "$gte": 20 } })).await?;
$lt
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "qty": { "$lt": 20 } })).await?;
$lte
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({ "qty": { "$lte": 20 } })).await?;
Find All Documents
use memquery::{errors::Error, memdb::MemDb, query}; let docs = coll.find(query!({})).await?;
Update Document
This shows examples how to use find_and_update
API.
Update document by replacing entire document:
use memquery::{errors::Error, memdb::MemDb, doc, query, update}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs_updated = coll .find_and_update( query!({"name": "Bob"}), update!({"nickname": "Bobcat", "voice": "meow"}), ) .await?; assert_eq!(docs_updated, 1); let docs = coll.find(query!({"nickname": "Bobcat"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["voice"], "meow");
Update specific field(s) in the document:
use memquery::{errors::Error, memdb::MemDb, doc, query, update}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs_updated = coll .find_and_update( query!({"name": "Bob"}), update!({"$set": { "name": "Roy", "age": 21, "email": "test@test.com"}}), ) .await?; assert_eq!(docs_updated, 1); let docs = coll.find(query!({"name": "Roy"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["age"], 21); assert_eq!(docs[0]["email"], "test@test.com");
Update document to remove field:
use memquery::{errors::Error, memdb::MemDb, doc, query, update}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs_updated = coll .find_and_update( query!({ "name": "Bob" }), update!({ "$set": { "name": "Roy", "age": 21, "email": "test@test.com" }}), ) .await?; assert_eq!(docs_updated, 1); let docs = coll.find(query!({"name": "Roy"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["age"], 21); assert_eq!(docs[0]["email"], "test@test.com"); let docs_updated2 = coll .find_and_update( query!({ "name": "Roy" }), update!({ "$unset": { "email": "" }}), ) .await?; assert_eq!(docs_updated2, 1); let docs = coll.find(query!({"name": "Roy"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["age"], 21); assert_eq!(docs[0]["email"], serde_json::Value::Null);
Increment value of the field in the document:
use memquery::{errors::Error, memdb::MemDb, doc, query, update}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs_updated = coll .find_and_update(query!({"name": "Bob"}), update!({"$inc": { "age": -5 }})) .await?; assert_eq!(docs_updated, 1); let docs = coll.find(query!({"name": "Bob"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["age"], 15.0);
Multiply value of a field in the document:
use memquery::{errors::Error, memdb::MemDb, doc, query, update}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs_updated = coll .find_and_update(query!({"name": "Bob"}), update!({"$mul": { "age": 5}})) .await?; assert_eq!(docs_updated, 1); let docs = coll.find(query!({"name": "Bob"})).await?; assert_eq!(docs.len(), 1); assert_eq!(docs[0]["age"], 100.0);
Delete Documents
use memquery::{errors::Error, memdb::MemDb, doc, query}; coll.insert(doc!({ "name": "Rob", "age": 25 })).await?; coll.insert(doc!({ "name": "Bob", "age": 20 })).await?; coll.insert(doc!({ "name": "Tom", "age": 30 })).await?; let docs = coll.find_and_delete(query!({})).await?; assert_eq!(docs.len(), 3); let docs_remaining = coll.find(query!({})).await?; assert_eq!(docs_remaining.len(), 0);
Sync API
To use sync API you need to enable it using sync
feature flag.
use memquery::{doc, errors::Error, query, memdb::MemDb}; coll.insert( doc!({ "item": { "name": "ab", "code": 123 }, "qty": 15, "tags": [ "A", "B", "C" ] }), )?; coll.insert(doc!({ "item": { "name": "cd", "code": 123 }, "qty": 20, "tags": [ "B" ] }))?; coll.insert(doc!({ "item": { "name": "ij", "code": 456 }, "qty": 25, "tags": [ "A", "B" ] }))?; coll.insert(doc!({ "item": { "name": "xy", "code": 456 }, "qty": 30, "tags": [ "B", "A" ] }))?; coll.insert( doc!({ "item": { "name": "mn", "code": 000 }, "qty": 20, "tags": [ [ "A", "B" ], "C" ] }), )?; let docs = coll.find(query!({ "item.code": { "$lte": 123 } }))?; assert_eq!(docs.len(), 3); assert_eq!(docs[0]["item"]["name"], "ab"); assert_eq!(docs[1]["item"]["name"], "cd"); assert_eq!(docs[2]["item"]["name"], "mn");
Modules
collection | Collection stores documents as JSON objects. |
errors | Errors reported by mem_query API. |
macros | |
memdb | MemDb allows creation, deletion and retrieval of collections of documents. |
Macros
doc | Construct a |
query | Construct a |
update | Construct a |
Type Definitions
DocumentCollection | |
Documents |