robertocannella/mongo-tut

mongo-tut

mongo db common use

Items
    .find({author: 'Roberto', isPublished: true})
    .sort({name: 1}) // sort ascending.  Use -1 for decending
    .limit(10) // get first 10 results
    .count() // returns total

Items
    .select({name: 1, tags: 1}) // return only the listed items (1 is for TRUE)

comparison operators - using $

• eq (equal)
• ne (not equal)
• gt (greater than)
• gte (greater than or equal to)
• lt (less than)
• lte (less than or equal to)
• in
• nin (not in)

Items
    .find({price: {$gt: 10}})  // find all entries greater than 10 
    .find({price: {$gte: 10}})  // find all entries greater than or equal to 10 
    .find({price: {$gte: 10, $lte: 20}})  // find all entries inclusive of 10-20
    .find({})

logical operators - using $

• or
• and

Items
    .find()
    .or([{author: 'Mosh'}, {isPublished: True}]) // find all itmes containing author:Mosh or isPublished

Items.
    .find()
    .and([ ]) // combining


async function getCourses() {
    return await Course
        .find({ isPublished: true })
        .or([{ tags: 'frontend' }, { tags: 'backend' }]) // pass and array of filtering objects
         [  { filter1 } , { filter 2 }  ]
        .sort({ price: -1 })
        .select({ name: 1, author: 1 })
}


async function getCourses() {
    return await Course
        .find({ isPublished: true })
        .or([{ name: /.*by.*$/i }, { price: { $gte: 15 } }])
}

regex

Items.
    find({author: /pattern/})

// Starts with 'Rob'

Items.
    find({author: /^Rob/}) //string that starts with 'Rob'

Items.
    find({author: /Cannella$/i}) //string that starts with 'Cannella' 
    (trailing 'i' negates case)

Items.
    find({author: /.*Rob.*$/i}) //string that contain 'Rob'

Pagination with .skip() and .limit()

// endpoint /api/courses?pageNumber=2&pageSize=10
    const pageNumber = 2;
    const pageSeze = 10;

    const courses = await Course
        .find({ author: 'Mosh', isPublised: true })
        .skip((pageNumber -1) * pageSize)
        .limit(pageSize)
        .sort({ name: 1 })
        .count()