clean way to get same field by different key - graphql

Here is the problem. I can get member by ID and my query looks like below:
{
member(memberId:[1,2]) {
firstName
lastName
contacts {
}
}
}
Now I need to add few more query to get member by name and email like below
{
member(email:["abc#xy.com","adc#xy.com"]) {
firstName
lastName
contacts {
}
}
}
{
member(name:["abc","adc"]) {
firstName
lastName
contacts {
}
}
}
How do I design my graphQL query and schema? Should my query have just 1 field with multiple optional arguments? like below
Field("member", ListType(Member),
arguments = ids :: email :: name,
resolve = (ctx) => {
val id : Seq[Int] = ctx.arg("memberId")
ctx.ctx.getMemberDetails(id)
})
Or should I have multiple query with different field under a schema. like below
Field("memberById", ListType(Member),
arguments = Id :: Nil,
resolve = (ctx) => {
val id : Seq[Int] = ctx.arg("memberId")
ctx.ctx.getMemberDetails(id)
})
Field("memberByEmail", ListType(Member),
arguments = email :: Nil,
resolve = (ctx) => {
val id : Seq[Int] = ctx.arg("memberId")
ctx.ctx.getMemberDetails(id)
})
Field("memberByName", ListType(Member),
arguments = name :: Nil,
resolve = (ctx) => {
val id : Seq[Int] = ctx.arg("memberId")
ctx.ctx.getMemberDetails(id)
})
Thank you in advance. let me know in case you need more details.

You should think about advantanges and disadvantages of both solutions.
If you will prepare separate fields, you will get a lot of boilerplate.
On the other hand you can set all possible inputs as OptionalInputType, it makes schema field only. Disadvantage of this solutions is that Sangria cannot validate a field that at least one argument should be required, so you have to cover this case with proper response or whatever.
The third option is to make generic solution at Schema level. You can create a query with two arguments filterName and filterValues, first would be EnumType for Id, Email, Name, the second would be a list of strings.
Such solution avoid disadvantages of both previous solutions, it has required fields and it doesn't need spreading fields in schema for every filter. Additionally if you want to add any additional function you have only edit FilterName enum and a resolver function to cover this.
Finally you schema will looks like this:
enum FilterName {
ID
EMAIL
NAME
}
type Query {
member(filterName: FilterName!, filterValues: [String]!): Member!
}

Related

How to find path to a field in a graphql query

I am very new to graphql. I have a following graphql query for an example:
query pets {
breed(some arguments)
{
name
items
{
owner(some arguments)
{
items
{
ID
ownerSnumber
country
address
school
nationality
gender
activity
}
}
name
phoneNumber
sin
}
}
}
Is it possible to parse a gql query and get the path of a field in the query?
For example I would like to get the path of 'ID'. For example from the above query, is it possible to get the path where the ID is: owner.items.ID
With https://graphql.org/graphql-js/ it exposes a fourth argument called resolve info. This field contains more information about the field.
Have a look at GraphQLObjectType config parameter type definition:
With a good start from the earlier answer, relying on the ResolveInfo you could do something like a recursive check going from child to parent:
export const getFieldPath = (path: Path): string => {
if (!path.prev) return `${path.key}`
return `${getFieldPath(path.prev)}.${path.key}`
}
And later in your resolver you could use it like:
const myFieldResolver = (parent, args, ctx, info) => {
const pathOfThisResolversField = getFieldPath(info.path)
// use your pathOfThisResolversField
return yourFieldResolvedData
};
Worth noting though, the solution above will include every node all the way to the query root, rather than just the ones you mentioned owner.items.ID

Return custom field based on other not requested field?

Let's say that I want to get a person's age using this query:
{
getUser(id: "09d14db4-be1a-49d4-a0bd-6b46cc1ceabb") {
full_name
age
}
}
I resolve my getUser query like this (I use node.js, type-graphql and knex):
async getUser(getUserArgs: GetUserArgs, fields: UserFields[]): Promise<User> {
// Return ONLY ASKED FIELDS
const response = await knex.select(this.getKnexFields(fields)).from(USER).whereRaw('id = ?', [getUserArgs.id]);
// returns { full_name: 'John Smith' }
return response[0];
}
The problem is that then I can't calculate age field, because I did not get born_at (datetime field stored in a db) in the first place:
#FieldResolver()
age(#Root() user: User, #Info() info: GraphQLResolveInfo): number {
console.log(user); // { full_name: 'John Smith' } no born_at field - no age, so error
// calculate age from born_at
return DateTime.fromJSDate(user.born_at).diff(DateTime.fromJSDate(new Date()), ['years']).years;
}
Is there some fancy graphql-build-in way / convention to predict that born_at will be needed instead of doing it manually through info / context?
You should always return full entity data from the query-level resolvers, so they are available for field resolvers.
The other solution is to manually maintain a list of required fields for field resolvers, so your "fields to knex" layer can always include them additionally".
Further improvements might be to can a list of additional columns based on the requested fields (thus the field resolvers that will be triggered).

GraphQL-java add variables to query

I am new to GraphQL. I know this is a basic question but hope someone could help me to add variables to my query as I tried many times and failed :(
In my query, below schema is used:
type Query {
ContinentInfo(id: ID): Continent
}
type Continent {
id : ID
name: String
countries: [Country]
}
type Country {
id : ID
name : String
population: Float
}
Below query is executed successfully:
{
ContinentInfo(id: "continent01") {
name
countries {
name
population
}
}
}
Then I want to add more conditions in the query, for example add a variable "populationMoreThan" to filter the result. so the query may look like:
{
ContinentInfo(id: "continent01") {
name
countries(populationMoreThan: $populationMoreThan) {
name
population
}
}
}
but it always failed when I tried to add this variable in the schema and in the query.
Could anyone provide me an example of adding variable in my case?
Also, it looks I need to pass the parameter value into the query? Now I'm using graphql.GraphQL.execute(queryString) to pass the query string. How to pass the variable value here?
Finally found a way to filter the result.
Update the schema with:
type Continent {
id : ID
name: String
countries(populationMoreThan: Float = 0): [Country]
}
And query with:
{
ContinentInfo(id: "continent01") {
name
countries(populationMoreThan: 1.0) {
name
population
}
}
}

LINQ GroupBy on single property

I am just not understanding the LINQ non-query syntax for GroupBy.
I have a collection of objects that I want to group by a single property. In this case Name
{ Id="1", Name="Bob", Age="23" }
{ Id="2", Name="Sally", Age="41" }
{ Id="3", Name="Bob", Age="73" }
{ Id="4", Name="Bob", Age="34" }
I would like to end up with a collection of all the unique names
{ Name="Bob" }
{ Name="Sally" }
Based on some examples I looked at I thought this would be the way to do it
var uniqueNameCollection = Persons.GroupBy(x => x.Name).Select(y => y.Key).ToList();
But I ended up with a collection with one item. So I though maybe I was over complicating things with the projection. I tried this
var uniqueNameCollection = Persons.GroupBy(x => x.Name).ToList();
Same result. I ended up with a single item in the collection. What am I doing wrong here? I am just looking to GroupBy the Name property.
var names = Persons.Select(p => p.Name).Distinct().ToList()
If you just want names
LINQ's GroupBy doesn't work the same way that SQL's GROUP BY does.
GroupBy takes a sequence and a function to find the field to group by as parameters, and return a sequence of IGroupings that each have a Key that is the field value that was grouped by and sequence of elements in that group.
IEnumerable<IGrouping<TSource>> GroupBy<TSource, TKey>(
IEnumerable<TSource> sequence,
Func<TSource, TKey> keySelector)
{ ... }
So if you start with a list like this:
class Person
{
public string Name;
}
var people = new List<Person> {
new Person { Name = "Adam" },
new Person { Name = "Eve" }
}
Grouping by name will look like this
IEnumerable<IGrouping<Person>> groups = people.GroupBy(person => person.Name);
You could then select the key from each group like this:
IEnumerable<string> names = groups.Select(group => group.Key);
names will be distinct because if there were multiple people with the same name, they would have been in the same group and there would only be one group with that name.
For what you need, it would probably be more efficient to just select the names and then use Distinct
var names = people.Select(p => p.Name).Distinct();
var uniqueNameCollection = Persons.GroupBy(x => x.Name).Select(y => y.Key).ToList();
Appears valid to me. .net Fiddle showing proper expected outcome: https://dotnetfiddle.net/2hqOvt
Using your data I ran the following code statement
var uniqueNameCollection = people.GroupBy(x => x.Name).Select(y => y.Key).ToList();
The return results were List
Bob
Sally
With 2 items in the List
run the following statement and your count should be 2.
people.GroupBy(x => x.Name).Select(y => y.Key).ToList().Count();
Works for me, download a nugget MoreLinq
using MoreLinq
var distinctitems = list.DistinctBy( u => u.Name);

IN and NOT IN with Linq to Entities (EF4.0)

This has been ruining my life for a few days now, time to ask...
I am using Entity Framework 4.0 for my app.
A Location (such as a house or office) has one or more facilities (like a bathroom, bedroom, snooker table etc..)
I want to display a checkbox list on the location page, with a checkbox list of facilities, with the ones checked that the location currently has.
My View Model for the facilities goes like this...
public class FacilityViewItem
{
public int Id { get; set; }
public string Name { get; set; }
public bool Checked { get; set; }
}
So when im passing the Location View Model to the UI, i want to pass a List<T> of facilities where T is of type FacilityViewItem.
To get the facilities that the location already has is simple - i make a query using Location.Facilities which returns an EntityCollection where T is of type Facility. This is because Facilities is a navigation property....
var facs = from f in location.Facilities
select new FacilityViewItem()
{
Id = f.FacilityId,
Name = f.Name,
Checked = true
};
So here is where my problem lies - i want the rest of the facilities, the ones that the Location does not have.
I have tried using Except() and Any() and Contains() but i get the same error.
Examples of queries that do not work...
var restOfFacilities = from f in ctx.Facilities
where !hasFacilities.Contains(f)
select new FacilityViewItem()
{
Id = f.FacilityId,
Name = f.Name
};
var restOfFacilities = ctx.Facilities.Except(facilitiesThatLocationHas);
var notFacs = from e in ctx.Facilities
where !hasFacilities.Any(m => m.FacilityId == e.FacilityId)
select new FacilityViewItem()
{
Id = e.FacilityId,
Name = e.Name
};
And the error i get with every implementation...
System.NotSupportedException was unhandled
Message=Unable to create a constant value of type 'Chapter2ConsoleApp.Facility'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
What am i overlooking here?
ironically enough i solved it in a matter of hours after i posted the question on here, after days of suffering.
The error is basically saying 'i dont know how to calculate what items are not included by comparing strongly typed objects. Give me a list of Ints or some simple types, and i can take care of it'.
So, first you need to get a list of the primary keys, then use that in the contains clause...
//get the primary key ids...
var hasFacilityIds = from f in hasFacilities
select f.FacilityId;
//now use them in the contains clause...
var restOfFacilities = from f in ctx.Facilities
where !hasFacilityIds.Contains(f.FacilityId)
select new FacilityViewItem()
{
Id = f.FacilityId,
Name = f.Name
};
The first query seems fine, but you need to compare the Ids:
var restOfFacilities = from f in ctx.Facilities
where !facs.Select(fac => fac.Id).Contains(f.Id)
select f;
I wanna see what's hasFacilities, anyway, as L2E shows, "Only primitive types ('such as Int32, String, and Guid') are supported in this context", so I suppose you must retrieve first the data and put into a collection of FacilityViewItem.
var restOfFacilities = ctx
.Facilities
.Where(f => !hasFacilities.Contains(f))
.Select(f => new { f.FacilityId, f.Name })
.ToList()
.Select(f => new FacilityViewItem {
Id = f.FacilityId,
Name = f.Name
});
var notFacs = ctx
.Facilities
.Where(e => !hasFacilities.Any(m => m.FacilityId == e.FacilityId))
.Select(e => new { e.FacilityId, e.Name })
.ToList()
.Select(e => new FacilityViewItem {
Id = e.FacilityId,
Name = e.Name
});
hope it helps

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