i am using the angular-fullstack yeoman generator. created a schema for a Product, and a set of api crud operations. all works well. now in the get list operations, i don't want to receive all the fields, only a subset. like a select in sql. i would also wish to alter one value. instead of the price, i need price * 1.1 .
how to do that?
here is the code for the index method (returns list of products):
// Gets a list of Products
export function index(req, res) {
Product.findAsync()
.then(respondWithResult(res))
.catch(handleError(res));
}
function respondWithResult(res, statusCode) {
statusCode = statusCode || 200;
return function(entity) {
if (entity) {
res.status(statusCode).json(entity);
}
};
}
As stated in the documentation, .find() takes two params, query and projection.
// params
Product.findAsync(query, projection)
You can use projection to "select" a subset of fields;
// example
Product.findAsync({}, { _id: 1, name: 1, description: 1 })
// result, only the three specified field will be returned
[
{ _id: 'abc123', name: 'Some name', description: 'Some description'},
{...}
]
If you want to manipulate data I think you have to use the aggregation pipeline
Related
I am working with a PostgreSQL database using Prisma. I have a bulk update command which I want to fail if any of the records have changed since my last read.
My schema:
model OrderItem {
id String #id #default(uuid()) #db.Uuid
quantity Int
lastUpdated DateTime #updatedAt #map("last_updated")
##map("order_item")
}
I have written a query which works, but I built the query manually rather than using Prisma's safe query builder tools.
My query:
type OrderItemType = {
id: string;
quantity: number;
lastUpdated: Date;
}
type OrderItemUpdateDataType = {
quantity: number;
}
const updateByIds = async (
orderItemIdLastUpdatedTuples: ([OrderItemType['id'], OrderItemType['lastUpdated']])[],
orderItemUpdateData: OrderItemUpdateDataType,
) => {
// Optimistic concurrency - try updating based on last known "last updated" state. If mismatch, fail.
await prisma.$transaction(async (prisma) => {
// TODO: Prefer prisma.$queryRaw. Prisma.join() works on id[], but not on [id, lastUpdated][]
const idLastUpdatedPairs = orderItemIdLastUpdatedTuples
.map(([id, lastUpdated]) => `(uuid('${id}'), '${lastUpdated.toISOString()}')`)
.join(', ');
const query = `SELECT * FROM order_item WHERE (id, last_updated) in ( ${idLastUpdatedPairs} )`;
const items = await prisma.$queryRawUnsafe<OrderItem[]>(query);
// If query doesn't match expected update count then another query has outraced and updated since last read.
const itemIds = orderItemIdLastUpdatedTuples.map(([id]) => id);
if (items.length !== orderItemIdLastUpdatedTuples.length) {
throw new ConcurrentUpdateError(`Order Items ${itemIds.join(', ')} were stale. Failed to update.`);
}
await prisma.orderItem.updateMany({
where: { id: { in: itemIds } },
data: orderItemUpdateData,
});
});
};
This function wants to update a set of items. It accepts a list of tuples - id/lastUpdated pairs. It starts an explicit transaction, then performs an unsafe SELECT query to confirm the items to affect haven't been updated, then updates. This is following the guidance of Prisma's docs here - https://www.prisma.io/docs/concepts/components/prisma-client/transactions#interactive-transactions-in-preview
I was hoping to achieve the same results using prisma.$queryRaw rather than prisma.$queryRawUnsafe or even using implicit transactions rather than an explicit transaction wrapper. I wasn't able to find a syntax for expressing "where in tuple" using either of these approaches, though.
I am able to express what I want using implicit transactions when updating a single record. An example here would look like:
const { count } = await prisma.orderItem.updateMany({
where: { id, lastUpdated },
data: orderItemUpdateData,
});
and when using an explicit, safe query I stumbled on joining the array of tuples properly.
From the Prisma documentation, https://www.prisma.io/docs/concepts/components/prisma-client/raw-database-access#tagged-template-helpers, there exists a Prisma.join command (which happens implicitly when using their tagged template helper syntax) but I wasn't able to generate a valid output when feeding it an array of tuples.
Did I miss anything? Does Prisma support joining a tuple using their safe query template syntax?
I have got a data structure:
{
field: 1,
field: 3,
field: [
{ _id: xxx , subfield: 1 },
{ _id: xxx , subfield: 1 },
]
}
I need to update a certain element in the array.
So far I can only do that by pulling out old object and pushing in a new one, but it changes the file order.
My implementation:
const product = await ProductModel.findOne({ _id: productID });
const price = product.prices.find( (price: any) => price._id == id );
if(!price) {
throw {
type: 'ProductPriceError',
code: 404,
message: `Coundn't find price with provided ID: ${id}`,
success: false,
}
}
product.prices.pull({ _id: id })
product.prices.push(Object.assign(price, payload))
await product.save()
and I wonder if there is any atomic way to implement that. Because this approach doesn't seem to be secured.
Yes, you can update a particular object in the array if you can find it.
Have a look at the positional '$' operator here.
Your current implementation using mongoose will then be somewhat like this:
await ProductModel.updateOne(
{ _id: productID, 'prices._id': id },//Finding Product with the particular price
{ $set: { 'prices.$.subField': subFieldValue } },
);
Notice the '$' symbol in prices.$.subField. MongoDB is smart enough to only update the element at the index which was found by the query.
I have two models in Objection - "brands" and "offers".
Brand:
const { Model } = require('objection')
class Brand extends Model {
static get tableName() {
return 'brands'
}
...
static get relationMappings() {
const Offer = require('./offer-model')
return {
offer: {
relation: Model.HasManyRelation,
modelClass: Offer,
join: { from: 'brands.id', to: 'offers.brand_id' }
}
}
}
}
Offer:
const { Model } = require('objection')
class Offer extends Model {
static get tableName() {
return 'offers'
}
}
A brand has many offers, but I want to get brands which have at least 1 offer using withGraphFetched, excluding brands which have no offers. Here's what I have so far:
const brandModel = this.objection.models.brand
const query = brandModel.query().withGraphFetched('offer')
query.page(page, page_size)
const offers = await query
This returns the "joined" data, but also returns brands which don't have offers. For example:
[{
id:1,
name: 'brand 1',
offers: [{offerId: 1, offerName: 'offer 1'}]
},{
id:2,
name: 'brand 2',
offers: []
}]
In the above data, I don't want the brand with ID 2 to be in the result set.
I am using Objection/Knex to paginate the results, so I can't just exclude the brands with empty object arrays after the query has been executed.
I can achieve this using raw queries, but that means I can't use the Objection dynamic attributes and a few other key parts of Objection.
Thanks!
You can just tack a whereExists onto the query; something like
const query = brandModel.query()
.withGraphFetched('offer')
.whereExists(
(qb) => qb.select('id').from('offers')
.where('offers.brand_id', knex.ref('brands.id'))
);
Even though the whereExists bit is directly Knex, the query still goes through your models so stuff you've defined there should still apply (maybe unless you're doing something very wild that directly affects the columns used inside the whereExists)
// my db structure now
rcv : {
visible: 'all',
ids: [
[0] : userId,
[1] : user2Id ]
}
this is how i query to get the data it works.
//service.ts
getAlbumByUserId(userId) {
return this.afs.collection('albums', ref => ref.where('rcv.visible', '==', 'all').where('rcv.ids', 'array-contains', userId)).valueChanges();
}
//component.ts
this.service.getAlbumByUserId(this.userId);
but i want to set the structure like this but i don't know how to query nested objects in firebase
// database structure
rcv : {
visible: 'all',
ids: {
userId: {
id: userId
}
user2Id: {
id: user2Id
}
}
}
You're looking for the array-contains operator, which can check if a field that is an array contains a certain value.
You're already using the correct array-contains operator, but not with the correct syntax. The array-contains operator checks whether any element of your array is exactly the same as the value you pass in. So you need to pass in the complete value that exists in the array:
ref.where('rcv.visible', '==', 'all').where('rcv.ids', 'array-contains', { id: userId })
As you add more data to the array, it may become unfeasible to reproduce the entire array element for the query. In that case, the common approach is to add an additional field where you keep just the IDs.
So you'd end up with one field (say rcv.users) where you keep all details about the receiving users, and one field (say rcv.ids) where you just keep their IDs, and that you use for querying.
I have the following schemas for the document Folder:
var permissionSchema = new Schema({
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
});
var folderSchema = new Schema({
name: { type: string },
permissions: [ permissionSchema ]
});
So, for each Page I can have many permissions. In my CMS there's a panel where I list all the folders and their permissions. The admin can edit a single permission and save it.
I could easily save the whole Folder document with its permissions array, where only one permission was modified. But I don't want to save all the document (the real schema has much more fields) so I did this:
savePermission: function (folderId, permission, callback) {
Folder.findOne({ _id: folderId }, function (err, data) {
var perm = _.findWhere(data.permissions, { _id: permission._id });
_.extend(perm, permission);
data.markModified("permissions");
data.save(callback);
});
}
but the problem is that perm is always undefined! I tried to "statically" fetch the permission in this way:
var perm = data.permissions[0];
and it works great, so the problem is that Underscore library is not able to query the permissions array. So I guess that there's a better (and workgin) way to get the subdocument of a fetched document.
Any idea?
P.S.: I solved checking each item in the data.permission array using a "for" loop and checking data.permissions[i]._id == permission._id but I'd like a smarter solution, I know there's one!
So as you note, the default in mongoose is that when you "embed" data in an array like this you get an _id value for each array entry as part of it's own sub-document properties. You can actually use this value in order to determine the index of the item which you intend to update. The MongoDB way of doing this is the positional $ operator variable, which holds the "matched" position in the array:
Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{
"$set": {
"permissions.$": permission
}
},
function(err,doc) {
}
);
That .findOneAndUpdate() method will return the modified document or otherwise you can just use .update() as a method if you don't need the document returned. The main parts are "matching" the element of the array to update and "identifying" that match with the positional $ as mentioned earlier.
Then of course you are using the $set operator so that only the elements you specify are actually sent "over the wire" to the server. You can take this further with "dot notation" and just specify the elements you actually want to update. As in:
Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{
"$set": {
"permissions.$.role": permission.role
}
},
function(err,doc) {
}
);
So this is the flexibility that MongoDB provides, where you can be very "targeted" in how you actually update a document.
What this does do however is "bypass" any logic you might have built into your "mongoose" schema, such as "validation" or other "pre-save hooks". That is because the "optimal" way is a MongoDB "feature" and how it is designed. Mongoose itself tries to be a "convenience" wrapper over this logic. But if you are prepared to take some control yourself, then the updates can be made in the most optimal way.
So where possible to do so, keep your data "embedded" and don't use referenced models. It allows the atomic update of both "parent" and "child" items in simple updates where you don't need to worry about concurrency. Probably is one of the reasons you should have selected MongoDB in the first place.
In order to validate subdocuments when updating in Mongoose, you have to 'load' it as a Schema object, and then Mongoose will automatically trigger validation and hooks.
const userSchema = new mongoose.Schema({
// ...
addresses: [addressSchema],
});
If you have an array of subdocuments, you can fetch the desired one with the id() method provided by Mongoose. Then you can update its fields individually, or if you want to update multiple fields at once then use the set() method.
User.findById(userId)
.then((user) => {
const address = user.addresses.id(addressId); // returns a matching subdocument
address.set(req.body); // updates the address while keeping its schema
// address.zipCode = req.body.zipCode; // individual fields can be set directly
return user.save(); // saves document with subdocuments and triggers validation
})
.then((user) => {
res.send({ user });
})
.catch(e => res.status(400).send(e));
Note that you don't really need the userId to find the User document, you can get it by searching for the one that has an address subdocument that matches addressId as follows:
User.findOne({
'addresses._id': addressId,
})
// .then() ... the same as the example above
Remember that in MongoDB the subdocument is saved only when the parent document is saved.
Read more on the topic on the official documentation.
If you don't want separate collection, just embed the permissionSchema into the folderSchema.
var folderSchema = new Schema({
name: { type: string },
permissions: [ {
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
} ]
});
If you need separate collections, this is the best approach:
You could have a Permission model:
var mongoose = require('mongoose');
var PermissionSchema = new Schema({
role: { type: String },
create_folders: { type: Boolean },
create_contents: { type: Boolean }
});
module.exports = mongoose.model('Permission', PermissionSchema);
And a Folder model with a reference to the permission document.
You can reference another schema like this:
var mongoose = require('mongoose');
var FolderSchema = new Schema({
name: { type: string },
permissions: [ { type: mongoose.Schema.Types.ObjectId, ref: 'Permission' } ]
});
module.exports = mongoose.model('Folder', FolderSchema);
And then call Folder.findOne().populate('permissions') to ask mongoose to populate the field permissions.
Now, the following:
savePermission: function (folderId, permission, callback) {
Folder.findOne({ _id: folderId }).populate('permissions').exec(function (err, data) {
var perm = _.findWhere(data.permissions, { _id: permission._id });
_.extend(perm, permission);
data.markModified("permissions");
data.save(callback);
});
}
The perm field will not be undefined (if the permission._id is actually in the permissions array), since it's been populated by Mongoose.
just try
let doc = await Folder.findOneAndUpdate(
{ "_id": folderId, "permissions._id": permission._id },
{ "permissions.$": permission},
);