I am using [BookshelfJS][bookshelfjs] for my ORM and am wondering how to access data on a though table.
I have 3 Models, Recipe, Ingredient and RecipeIngredient which joins the two.
var Recipe = BaseModel.extend({
tableName: 'recipe',
defaults: { name: null },
ingredients: function () {
return this
.belongsToMany('Ingredient')
.through('RecipeIngredient')
.withPivot(['measurement']);
}
}));
var Ingredient = BaseModel.extend({
tableName: 'ingredients',
defaults: { name: null },
recipes: function () {
return this
.belongsToMany('Recipe')
.through('RecipeIngredient');
}
}));
var RecipeIngredient = BaseModel.extend({
tableName: 'recipe_ingredients',
defaults: { measurement: null },
recipe: function () {
return this.belongsToMany('Recipe');
},
ingredient: function () {
return this.belongsToMany('Ingredient');
}
}));
I then attempt to retrieve a Recipe along with all the Ingredients however cannot work out how to access measurement on the RecipeIngredient.
Recipe
.forge({
id: 1
})
.fetch({
withRelated: ['ingredients']
})
.then(function (model) {
console.log(model.toJSON());
})
.catch(function (err) {
console.error(err);
});
Return:
{
"id": 1,
"name": "Delicious Recipe",
"ingredients": [
{
"id": 1,
"name": "Tasty foodstuff",
"_pivot_id": 1,
"_pivot_recipe_id": 1,
"_pivot_ingredient_id": 1
}
]
}
With no measurement value.
I had thought that the .withPivot(['measurement']) method would have grabbed the value but it does not return any additional data.
Have I missed something or misunderstood how this works?
I'm not exactly sure why you want to use through. If it's just a basic many-to-many mapping, you can achieve this by doing the following:
var Recipe = BaseModel.extend({
tableName: 'recipe',
defaults: { name: null },
ingredients: function () {
return this
.belongsToMany('Ingredient').withPivot(['measurement']);
}
}));
var Ingredient = BaseModel.extend({
tableName: 'ingredients',
defaults: { name: null },
recipes: function () {
return this
.belongsToMany('Recipe').withPivot(['measurement']);;
}
}));
You don't need an additional model for junction table. Just be sure to define a junction table in your database as ingredients_recipe (alphabetically joining the name of tables!). Or , you can provide your own custom name to belongsToMany function for what the junction table should be named. Be sure to have ingredients_id and recipe_id in ingredients_recipe
This is pretty much it. Then you can do
Recipe
.forge({
id: 1
})
.fetch({
withRelated: ['ingredients']
})
.then(function (model) {
console.log(model.toJSON());
})
.catch(function (err) {
console.error(err);
});
Related
I need the expert advice for this code. I need to know Is there any better way to solve this.
I am using the mongoose for db. I have a dataset like this:
Below is matchTable:
{
_id: 617bc0113176d717f4ddd6ce,
car: [],
status: true
},
{
_id: 617bc0113176d717f4ddd6cg,
car: [
{
aid: '5c1b4ffd18e2d84b7d6febcg',
}
],
status: true
}
And I have a Car table in which car name is there on behalf of id
like this
{ _id: ObjectId('5c1b4ffd18e2d84b7d6febce'), name: 'ford' },
{ _id: ObjectId('5c1b4ffd18e2d84b7d6febcg'), name: 'mitsubishi' },
So I want to make join the data from car table, so that response get name on behalf of aid.
Desired result will be like
{
_id: 617bc0113176d717f4ddd6ce,
car: [],
status: true
},
{
_id: 617bc0113176d717f4ddd6cg,
car: [
{
aid: '5c1b4ffd18e2d84b7d6febcg',
name: 'mitsubishi'
}
],
status: true
}
For that I have to merge the car table on matchTable. I have done this but I want to give some suggestion that is there any better way to do or is it fine. I need expert advice.
const getData = await matchTable.find(
{ status: true }
).lean().exec();
let dataHolder = [];
await Promise.all (
getData.map(async x => {
await Promise.all(
x.car.map(async y => {
let data = await Car.findOne(
{ _id: ObjectId(y.aid) },
{ name: 1 }
).lean().exec();
y.name = '';
if (data) {
y.name = data.name;
}
})
)
// If I return { ...x }, then on response it will return {}, {} on car column
dataHolder.push(x) //So I have chosen this approach
})
);
Please guide me if any better and efficient solution is there. Thanks in advance
You can make use of aggregation here.
const pipeline = [
{
$match : { status : true }
},
{
$unwind: '$matchtable',
},
{
$lookup: {
from: "cars",
localField: "car.aid",
foreignField: "_id",
as: "matchcars"
}
},
{
$addFields: {
"car.carName": { $arrayElemAt: ["$matchcars.name", 0] }
}
},
{
$group: {
_id: "$_id",
cars: { $push: "$matchcars" }
}
}
]
const result = await matchTable.aggregate(pipeline).exec();
Please make sure, aid field inside car array (in matchTable collection) is an ObjectId because its being matched to _id (which is an ObjectId) inside cars collection.
I am trying to create a model Users with many-to-many association to itself to allow users to follow another users. In one query I want to retrieve the Users followed by the current user; in another query I want to retrieve the people that follows the current user.
This is my Users model:
module.exports = (sequelize, Sequelize) => {
const Users = sequelize.define(
'Users',
{
id: {
type: Sequelize.INTEGER,
autoIncrement: true,
primaryKey: true,
},
name: {
type: Sequelize.STRING,
},
},
);
Users.associate = function(models) {
Users.belongsToMany(Users, { as: 'following', through: models.UsersUsers });
};
return Users;
};
I declare UsersUsers, just in case I need to add any field there:
module.exports = (sequelize, Sequelize) => {
const UsersUsers = sequelize.define(
'UsersUsers',
{}
);
UsersUsers.associate = function(models) {};
return UsersUsers;
};
Then I query Users as:
models.Users.findOne({
where: {
id: req.params.id,
},
include: [
{
model: models.Users,
as: 'following',
},
],
})
.then((results) => {
return res.send({
User: results,
});
})
.catch((error) => {
return res.send(String(error));
});
And I get this result:
{
"User": {
"id": 1,
"name": "User1",
"following": [
{
"id": 2,
"name": "User2",
"UsersUsers": {
"UserId": 1,
"followingId": 2
}
},
{
"id": 3,
"name": "User3",
"UsersUsers": {
"UserId": 1,
"followingId": 3
}
},
{
"id": 4,
"name": "User4",
"UsersUsers": {
"UserId": 1,
"followingId": 4
}
}
]
}
}
Now the questions:
In my current query, how do I exclude "UsersUsers" from the result? attributes: { exclude: ['UsersUsers'] } did not work…
How do I create a query to retrieve the current user with the users that follows him instead of the users followed by him?
Thanks!
--
EDIT:
The solution for the question 1. is to add through: { attributes: [] } to the included model:
models.Users.findOne({
where: {
id: req.params.id,
},
include: [
{
model: models.Users,
as: 'following',
through: {
attributes: [],
},
},
],
})
.then((results) => {
return res.send({
User: results,
});
})
.catch((error) => {
return res.send(String(error));
});
Still pending question 2!
Users.findAll({
include: [
{
model: models.Users,
as: 'following',
through: {
attributes: [],
},
},
],
where : {
id : [connection.literal(` write raw sql query to get followingId here`)]
}
})
.then(result => {
res.json(result);
}).catch(error=>{
res.json(error);
});
I'm not sure if this gonna work, still play around this and do let me know if this worked or if you found any solution.
I am making a GraphQL API where I would be able to retrieve a car object by its id or retrieve all the cars when no parameter is provided.
Using the code below, I am successfully able to retrieve a single car object by supplying id as a parameter.
However, in the case where I would expect an array of objects i.e. when I supply no parameter at all, I get no result on GraphiQL.
schema.js
let cars = [
{ name: "Honda", id: "1" },
{ name: "Toyota", id: "2" },
{ name: "BMW", id: "3" }
];
const CarType = new GraphQLObjectType({
name: "Car",
fields: () => ({
id: { type: GraphQLString },
name: { type: GraphQLString }
})
});
const RootQuery = new GraphQLObjectType({
name: "RootQueryType",
fields: {
cars: {
type: CarType,
args: {
id: { type: GraphQLString }
},
resolve(parent, args) {
if (args.id) {
console.log(cars.find(car => car.id == args.id));
return cars.find(car => car.id == args.id);
}
console.log(cars);
//***Problem Here***
return cars;
}
}
}
});
Test queries and their respective results:
Query 1
{
cars(id:"1"){
name
}
}
Query 1 Response (Success)
{
"data": {
"cars": {
"name": "Honda"
}
}
}
Query 2
{
cars{
name
}
}
Query 2 Response (Fail)
{
"data": {
"cars": {
"name": null
}
}
}
Any help would be much appreciated.
A Car and a List of Cars are effectively two separate types. A field cannot resolve to a single Car object one time, and an array of Car object another.
Your query is returning null for the name because you told it the cars field would resolve to a single object, but it resolved to an array instead. As a result, it's looking for a property called name on the array object and since one doesn't exist, it's returning null.
You can handle this in a couple of different ways. To keep things to one query, you can use filter instead of find and change the type of your query to a List.
cars: {
type: new GraphQLList(CarType), // note the change here
args: {
id: {
type: GraphQLString
},
},
resolve: (parent, args) => {
if (args.id) {
return cars.filter(car => car.id === args.id);
}
return cars;
}
}
Alternatively, you could split this into two separate queries:
cars: {
type: new GraphQLList(CarType),
resolve: (parent, args) => cars,
},
car: {
type: CarType,
args: {
id: {
// example of using GraphQLNonNull to make the id required
type: new GraphQLNonNull(GraphQLString)
},
},
resolve: (parent, args) => cars.find(car => car.id === args.id),
}
Check the docs for more examples and options.
I have a product table in DynamoDB which has some items. Now I need to add list of buyers to the product which can grow i.e. append to list. It works for if I have an empty list or a list with some items in the table item but for the first addition it throws an error. Is there any way to check if list exists then append else add a list. here is my code
let params = {
TableName: "product",
ExpressionAttributeNames: {
"#Y": "buyer"
},
ExpressionAttributeValues: {
":y": ["PersonXYZ"]
},
Key: {
id: 'Hy2H4Z-lf'
},
UpdateExpression: "SET #Y = list_append(#Y,:y)"
};
updateItemInDDB(params).then((data) => {
res.status(200).send(data);
}, err => {
console.log(err);
res.sendStatus(500);
});
UpdateItemInDDB is just a function which takes a params and run dnamodb code on it. I am using javascript sdk for DynamoDB with Document Client.
var params = {
TableName: "user",
Key: {
"user_id": {
S: user_id
}
},
UpdateExpression: "SET #ri = list_append(if_not_exists(#ri, :empty_list), :vals)",
ExpressionAttributeNames: {
"#ri": "images"
},
ExpressionAttributeValues: {
":vals": {"L": [{
"S": "dummy data"
}]},
":empty_list": {"L": []}
},
ReturnValues: 'ALL_NEW'
};
":empty_list": {"L": []}
this is important if you want to set empty list, otherwise it will give below exception.
"errorMessage": "ExpressionAttributeValues contains invalid value: Supplied AttributeValue is empty, must contain exactly one of the supported datatypes for key :empty_list",
"errorType": "ValidationException"
EDIT: Nest the conditional expressions
You could run SET append_list with a ConditionalExpression that the attribute does exist, then if that fails run SET with a ConditinalExpression that the attribute does not exist.
let params1 = {
TableName: "product",
ExpressionAttributeNames: {
"#Y": "buyer"
},
ExpressionAttributeValues: {
":y": ["PersonXYZ"]
},
Key: {
id: 'Hy2H4Z-lf'
},
ConditionExpression: "attribute_exists(buyer)",
UpdateExpression: "SET #Y = list_append(#Y,:y)"
};
updateItemInDDB(params1).then((data) => {
res.status(200).send(data);
}, err => {
console.log(err);
let params2 = {
TableName: "product",
ExpressionAttributeNames: {
"#Y": "buyer"
},
ExpressionAttributeValues: {
":y": ["PersonXYZ"]
},
Key: {
id: 'Hy2H4Z-lf'
},
ConditionExpression: "attribute_not_exists(buyer)",
UpdateExpression: "SET #Y = (#Y,:y)"
};
updateItemInDDB(params2).then((data) => {
res.status(200).send(data);
}, err => {
console.log(err);
res.sendStatus(500);
});
});
I have two api requests and both gets a result of JSON. The first request is "account" request and second is "Container" request. Now:
Request for all Accounts (accountid: 1, name: account1, blabla)
Request for all Containers (accountid: 1, name: Container1, blabla)
This is the result JSON of Accounts:
account: [
{
accountId: "123456789",
fingerprint: null,
name: "Account2",
path: "accounts/123456789",
},
This is the result JSON of Containers:
{
accountId: "123456789",
containerId: "123****",
domainName: null,
fingerprint: "123*****",
name: "Container23",
path: "accounts/123456789/containers/123******",
publicId: "GTM-****"
},
As you can see the container result contains the accountid so im trying to merge those two results so it becomes this combined (container):
{
accountId: "123456789",
name: "Account2", <------ THIS is what i want to merge
containerId: "123****",
domainName: null,
fingerprint: "123*****",
name: "Container23",
path: "accounts/123456789/containers/123******",
publicId: "GTM-****"
},
Remember there are many containers and accounts not just one block.
What i have tried using underscore:
var mergedList = _.map($scope.GTMcontainers, function(data){
return _.extend(data, _.findWhere($scope.account, { id: data.accountId }));
});
console.log(mergedList);
Here is my AngularJS
function getContainer() {
$http.get("http://******")
.then(function (response) {
$scope.GTMcontainers = response.data;
console.log(response);
$scope.loading = false;
})
.then(function () {
$http.get("http://******")
.then(function (response2) {
$scope.account = response2.data;
console.log(response2);
var mergedList = _.map($scope.GTMcontainers, function(data){
return _.extend(data, _.findWhere($scope.account, { id: data.accountId }));
});
console.log(mergedList);
})
})
}
Using this underscore gives me exactly the same JSON result as i requested (no merge).
Hope some one has experience with this.
Thanks
Updated:
using simple javascript
var accounts = [
{
accountId: "123456789",
fingerprint: null,
name: "Account2",
path: "accounts/123456789",
},{
accountId: "123456780",
fingerprint: null,
name: "Account3",
path: "accounts/123456789",
}]
var containers =[{
accountId: "123456789",
containerId: "123****",
domainName: null,
fingerprint: "123*****",
name: "Container23",
path: "accounts/123456789/containers/123******",
publicId: "GTM-****"
},{
accountId: "123456780",
containerId: "123****",
domainName: null,
fingerprint: "123*****",
name: "Container24",
path: "accounts/123456789/containers/123******",
publicId: "GTM-****"
}]
var result=[];
containers.forEach(function(item){
var temp=accounts.find(function(d){return d.accountId == item.accountId});
if(temp)
item.name = temp.name;
result.push(item);
})
console.log(result);
I have faced that issue, I knew I have got responses, but data was not merged. So I have used callbacks.
function getContainer(callback) {
$http.get("http://******")
.then(function (response) {
$scope.GTMcontainers = response.data;
console.log(response);
$scope.loading = false;
})
.then(function () {
$http.get("http://******")
.then(function (response2) {
$scope.account = response2.data;
console.log(response2);
if(response && response2){
callback(response,response2);
}
})
})
}
At function call time--
getContainer(function(array1,array2){
if(array1 && array2 && array1.length>0 && array2.length>0){
var mergedList = _.map(array1, function(data){
return _.extend(data, _.findWhere(array2, { id: data.accountId }));
});
console.log(mergedList);
}
})