I want to select some of the Product's information after Category's infromation using linq to objects.
var test = Context.Categories.Select(t => new { t.CategoryID, t.CategoryName });
How can i select Product's information.
Category and Products have one-to-many relationship.
You can do this using LINQ query syntax as well
var test = from c in Context.Categories
from p in c.Products
select new { c.CategoryID, c.CategoryName, p.ProductName });
Behind the scenes this is synonymous to :
var test = Categories.SelectMany
(
c => c.Products,
(c, p) => new
{
c.CategoryID,
c.CategoryName,
p.ProductName
}
);
I found the answer , i use SelectMany() like this:
var test = Context.Categories.SelectMany(t=>t.Products).Select(t => new { t.CategoryID, t.Category.CategoryName,t.ProductName });
Related
I have the MySql tables schema below (resumed):
I need to Select only the category data in a Query using EFCore:
List<CategoryViewModel> viewModel = await _context.Category
.Join(_context.Product_Category, c => c.CategoryId, pc => pc.CategoryId, (c, pc) => new { c, pc })
.Join(_context.Product, cpc => cpc.pc.ProductId, p => p.ProductId, (cpc, p) => new { cpc, p })
.Where(cpcp => cpcp.p.EstablishmentId == paramEstablishmentId) //paramEstablishmentId comes via parameter
.Select(vm => new CategoryViewModel()
{
Id = vm.cpc.pc.category.CategortId,
Name = vm.cpc.pc.category.Name,
Image = vm.cpc.pc.category.ImagePath,
Description = vm.cpc.pc.category.Description
})
.ToListAsync();
But this query always result a list with zero models inside. I guarantee there are values in the database to be returned.
Any Ideia what i'm doing wrong?
Many Thanks!
You should use Include()function instead of join. For eg :
var blogs = context.Blogs
.Include(blog => blog.Posts)
.ToList();
Based on #Flyzzx Answer (many thanks, friend), i've modify my query to:
List<CategoryViewModel> viewModel = await _context.Product_Category
.Where(pc => pc.Product.EstablishmentId == EstablishmentId)
.Include(pc => pc.Product)
.Include(pc => pc.Category)
.Select(c => new CategoryViewModel()
{
Id = c.Category.Id,
Name = c.Category.Name,
Image = c.Category.ImagePath,
Description = c.Category.Description
}).Distinct()
.ToListAsync();
Basically, instead of select Categories, now i select Product_Category and use Include to add Products and Categories, making possible to use the Where Clause.
Note : I have not shared database schema as I am mainly looking for a help only w.r.t. last step which is 'left outer join' on 2 sub-queries.
select *
from
(select id
from Action
where id = 3) AS act1
left Outer Join
(select Action.name,
completed_At as completedAt,
deadline, notes,
ActionAssignedTo.action_Id as actionId,
from Action
inner join Employee
on Action.created_By_Id = Employee.id
and Employee.vendor_Id = 2
inner join ActionAssignedTo
on Action.id = ActionAssignedTo.action_Id
and ActionAssignedTo.action_Id = 3
where Action.created_By_Id = 7
group by Action.id
limit 2) AS act2
on act1.id = act2.actionId
I need to write this above query using Bookshelf
let options = {columns: [ 'Action.name', 'completed_At as completedAt',
'deadline', 'notes',
'ActionAssignedTo.action_Id as actionId',
]};
let action2 = new Action();
action2.query().innerJoin('Employee', function () {
this.on('Action.created_By_Id', 'Employee.id')
.andOn('Employee.vendor_Id', bookshelf.knex.raw(1));
});
action2.query().innerJoin('ActionAssignedTo', function () {
this.on('Action.id', 'ActionAssignedTo.action_Id')
.andOn('ActionAssignedTo.action_Id', bookshelf.knex.raw(5));
});
action2.query().where(function() {
this.where('Action.created_By_Id', empId)
});
action2.query().groupBy('Action.id');
action2.query().limit(2);
action2.query().columns(options.columns);
let action1;
action1 = Action.where('id', actionId);
action1.query().columns('id');
return bookshelf.knex.raw('select * from '
+ '(' + action1.query().toString() + ') AS act1'
+ ' left Outer Join '
+ '(' + action2.query().toString() + ') AS act2'
+ ' on act1.id = act2.actionId');
I am not keen on using bookshelf.knex.raw for using the left Outer Join as the output given by knex.raw and bookshelf differ.
Is there a way I can do the 'left Outer Join' directly using bookshelf library.
I looked into the code but it seems leftOuterJoin only takes table name as the first parameter and what I need is a query.
I think your main problem is that you're using Bookshelf like you would be using knex. Bookshelf is meant to be used with models you would define and then query on them.
Here is an example of what you should have as model
// Adding registry to avoid circular references
// Adding camelcase to get your columns names converted to camelCase
bookshelf.plugin(['bookshelf-camelcase', 'registry']);
// Reference: https://github.com/brianc/node-pg-types
// These two lines convert all bigint values coming from Postgres from JS string to JS integer.
// Removing these lines will mess up with Bookshelf count() methods and bigserial values
pg.types.setTypeParser(20, 'text', parseInt);
const Action = db.bookshelf.Model.extend({
tableName: 'Action',
createdBy: function createdBy() {
return this.belongsTo(Employee, 'id', 'created_By_Id');
},
assignedTo: function assignedTo() {
return this.hasMany(ActionAssignedTo, 'action_id');
},
});
const Employee = db.bookshelf.Model.extend({
tableName: 'Employee',
createdActions: function createdActions() {
return this.hasMany(Action, 'created_By_Id');
},
});
const ActionAssignedTo = db.bookshelf.Model.extend({
tableName: 'ActionAssignedTo',
action: function action() {
return this.belongsTo(Action, 'id', 'action_Id');
},
employee: function employee() {
return this.belongsTo(Employee, 'id', 'employee_Id');
},
});
module.exports = {
Action: db.bookshelf.model('Action', Action),
Employee: db.bookshelf.model('Employee', Employee),
ActionAssignedTo: db.bookshelf.model('ActionAssignedTo', ActionAssignedTo),
db,
};
You would then be able to fetch your results with a query like this
const Model = require('model.js');
Model.Action
.where({ id: 3 })
.fetchAll({ withRelated: ['createdBy', 'assignedTo', 'assignedTo.employee'] })
.then(data => {
// Do what you have to do
});
What your want to achieve is not possible with only one query in Bookshelf. You probably need to do a first query using knex to get a list of Action ids and then give them to Bookshelf.js
db.bookshelf.knex.raw(`
select ActionAssignedTo.action_Id as actionId,
from Action
inner join Employee
on Action.created_By_Id = Employee.id
and Employee.vendor_Id = ?
inner join ActionAssignedTo
on Action.id = ActionAssignedTo.action_Id
and ActionAssignedTo.action_Id = ?
where Action.created_By_Id = ?
group by Action.id
limit ?`,
[2, 3, 7, 2]
)
.then(result => {
const rows = result.rows;
// Do what you have to do
})
And then use the recovered Ids to get your Bookshelf query like this
Model.Action
.query(qb => {
qb.whereIn('id', rows);
})
.fetchAll({
withRelated: [{
'createdBy': qb => {
qb.columns(['id', 'firstname', 'lastname']);
},
'assignedTo': qb => {
qb.columns(['action_Id', 'employee_Id']);
},
'assignedTo.employee': qb => {
qb.columns(['id', 'firstname', 'lastname']);
},
}],
columns: ['id', 'name', 'completed_At', 'deadline', 'notes']
})
.fetchAll(data => {
// Do what you have to do
});
Note that the columns used for joins MUST BE in the columns list for each table. If you omit the columns, all the columns will be selected.
By default, Bookshelf will retrieve all columns and all root objects. The default is kind of LEFT OUTER JOIN.
i used this query:
$brands = TblBrand::find(array("id In (Select p.brand_id From EShop\\Models\\TblProduct as p Where p.id In (Select cp.product_id From EShop\\Models\\TblProductCategory as cp Where cp.group_id_1='$id'))", "order" => "title_fa asc"));
if($brands != null and count($brands) > 0)
{
foreach($brands as $brand)
{
$brandInProductCategory[$id][] = array
(
"id" => $brand->getId(),
"title_fa" => $brand->getTitleFa(),
"title_en" => $brand->getTitleEn()
);
}
}
TblBrand => 110 records
TblProduct => 2000 records
TblProductCategory => 2500 records
when i used this code, my site donot show and loading page very long time ...
but when i remove this code, my site show.
how to solve this problem?
The issue is your query. You are using the IN statement in a nested format, and that is always going to be slower than anything else. MySQL will need to first evaluate what is in the IN statement, return that and then do it all over again for the next level of records.
Try simplifying your query. Something like this:
SELECT *
FROM Brands
INNER JOIN Products ON Brand.id = Products.brand_id
INNER JOIN ProductCategory ON ProductCategory.product_id = Products.id
WHERE ProductCategory.group_id_1 = $id
To achieve the above, you can either use the Query Builder and get the results that way
https://docs.phalconphp.com/en/latest/api/Phalcon_Mvc_Model_Query_Builder.html
or if you have set up relationships in your models between brands, products and product categories, you can use that.
https://docs.phalconphp.com/en/latest/reference/model-relationships.html
example:
$Brands = Brands::query()
->innerJoin("Products", "Products.brand_id = Brand.id")
->innerJoin("ProductCategory", "ProductCategory.product_id = Products.id")
->where("ProductCategory.group_id_1 = :group_id:")
->bind(["group_id" => $id])
->cache(["key" => __METHOD__.$id] // if defined modelCache as DI service
->execute();
$brandInProductCategory[$id] = [];
foreach($Brands AS $Brand) {
array_push($brandInProductCategory[$id], [
"id" => $Brand->getId(),
"title_fa" => $Brand->getTitleFa(),
"title_en" => $Brand->getTitleEn()
]);
}
This must be an easy one, but I can't remember how I did it before.
I'm trying to make another query within the query where record IDs are match:
/*
tables:
models:
model_id
model_name
models_years:
model_year_id
model_id
year
*/
$models = DBW::run('SELECT * FROM models', [], true);
$models_years = DBW::run('SELECT * FROM models_years', [], true);
$output = [];
foreach ($models as $model)
{
$years = [];
foreach ($models_years as $model_year)
{
if ($model_year['model_id'] == $model['model_id'])
{
$years[] = $model_year['year'];
}
}
$output[] = [
'model_name' => $model['model_name'],
'years' => $years
];
}
var_dump( $output );
I use PDO (settings: ATTR_DEFAULT_FETCH_MODE = FETCH_ASSOC), and "DBW::run" function returns $stmt->fetchAll().
this is just an example of what I'm trying to do or improve, I know it's possible to do all of that in a single SQL, I've done it before and can't remember! :(
SELECT m.model_name, y.`year`
FROM models AS m
LEFT JOIN models_years As y ON m.model_id = y.model_id
OR from your original question, the following might be what you need:
SELECT m.model_name, group_concat(y.`year`) AS `year`
FROM models AS m
LEFT JOIN models_years As y ON m.model_id = y.model_id
GROUP BY 1
Why?
1 - Join table to reduce SQL calls
2 - GROUP the result (BY 1 == BY m.model_name, just a lazy shorthand here)
3 - group_concat(...) will by default produce: year1,year2,year3,... and then you can use PHP explode(',', ...) to change to array if you need
Join the tables, and use GROUP_CONCAT to combine all the years for each model. Then use explode() to split that into an array.
$output = DBW::run('select m.model_name, GROUP_CONCAT(y.year) AS years
FROM models AS m
LEFT JOIN models_years AS y ON m.model_id = y.model_id
GROUP BY m.model_id', [], true);
foreach ($output as &$row) {
$row['years'] = explode(',', $row['years']);
}
SELECT model_name, year FROM models, models_years WHERE
models.model_id=models_years.model_id
Or, if you prefer the JOIN syntax,
SELECT model_name, year FROM models JOIN models_years ON
models.model_id=models_years.model_id
another way to do this is with the sub select.
select * from models where model_id in (select model_id from models_years)
I would like to translate the following SQL into LINQ:
SELECT
(Select count(BidID)) as TotalBidNum,
(Select sum(Amount)) as TotalBidVal
FROM Bids
I've tried this:
from b in _dataContext.Bids
select new { TotalBidVal = b.Sum(p => p.Amount), TotalBidNum = b.Count(p => p.BidId) }
but get an error "Bids does not contain a definition for "Sum" and no extension method "Sum" accepting a first argument of type "Bids" could be found.
How can I do this in LINQ?
Thanks
CONCLUDING:
The final answer was:
var ctx = _dataContext.Bids;
var itemsBid = (from b in _dataContext.Bids
select new { TotalBidVal = ctx.Sum(p => p.Amount), TotalBidNum = ctx.Count() }).First();
You can write this query using GroupBy. The Lambda expression is as follows:
var itemsBid = db.Bids
.GroupBy( i => 1)
.Select( g => new
{
TotalBidVal = g.Sum(item => item.Amount),
TotalBidNum = g.Count(item => item.BidId)
});
You could try this out. The variable b is an entity (for every iteration) while ctx is an entityset which has the extension methods you need.
var ctx = _dataContext.Bids;
var result = ctx
.Select( x => new
{
TotalBidVal = ctx.Sum ( p => p.Amount ),
TotalBidNum = ctx.Count( p => p.BidId )
} )
.First();
here's an alternative to scartag's solution:
(from b in _dataContext.Bids.Take(1)
select new
{
TotalBidVal = _dataContext.Bids.Sum(p => p.Amount),
TotalBidNum = _dataContext.Bids.Count()
}).Single();
Although there's no real reason you can't just say:
var result = new
{
TotalBidVal = _dataContext.Bids.Sum(p => p.Amount),
TotalBidNum = _dataContext.Bids.Count()
};
It hits the database twice, but its very readable
You could do it using the Aggregate Clause.
Aggregate t In _dataContext.Bids
Into TotalBidNum = Count(BidID),
TotalBidVal = Sum(Amount)
If you're using Fx4+ or an extension dll for Fx2, you could also benfit from parallelism by using
Aggregate t In _dataContext.Bids.AsParallel