I want to modify the graphql syntax and parse process for my own needs.
E.g. that the client can send queries with path-based arguments:
type Foo {
name: String
anotherField: String
bar: Bar
}
type Bar {
name: String
anotherField: String
}
type Query {
foos(arg: String): [Foo]
}
#relevant part: bar.name
query {
foo(arg: bar.name) {
name
anotherField
}
}
Advantage: e.g. filter on nested objects without setting them in the query. I know that changes in the resolvers are necessary, but first the parser (and lexer!?) has to accept the "new" syntax. At the moment the concept is causing a
GraphQLError: Unexpected character ".".
Any ideas?
I know that some libraries like Prisma or Hasura have implemented good filter alternatives but i need my custom solution.
Related
QueryRenderer takes a “query” prop, which contains a topmost query of the application made of fragments for downstream components:
const LinkListPage = () => (<QueryRenderer
query={ rootQuery }
{ ...otherProps }
render={
(error, props) =>
<LinkList viewer={ props.viewer } />
}
/>)
/* ... */
const rootQuery = graphql`
query LinkListPageQuery {
viewer {
...LinkList_viewer
}
}
`
In the above example, the fragment “LinkList_viewer” is self-sufficient, and it tells us which container it supplies data to, and which prop it fills in.
Why the relay compiler does not assemble that root query on its own? Why do we need to repeat the typing of props.viewer, when it's immediately obvious and unambiguous what to pass where? Is there any case when manual construction of the root query helps us?
The root query is used to distinguish asking for data that is idempotent (query) from asking for data that will mutate the state (mutations) from data the behaves in other ways (subscriptions).
I think the philosophy in the Relay library is to not try and have too much magic in the implementation of using it, hence that lack of automatically passing the data in a query with only one node.
I am currently doing the facebook relayjs tutorial and I need help understanding this part of the tutorial, it states
Next, let's define a node interface and type. We need only provide a
way for Relay to map from an object to the GraphQL type associated
with that object, and from a global ID to the object it points to
const {nodeInterface, nodeField} = nodeDefinitions(
(globalId) => {
const {type, id} = fromGlobalId(globalId);
if (type === 'Game') {
return getGame(id);
} else if (type === 'HidingSpot') {
return getHidingSpot(id);
} else {
return null;
}
},
(obj) => {
if (obj instanceof Game) {
return gameType;
} else if (obj instanceof HidingSpot) {
return hidingSpotType;
} else {
return null;
}
}
);
On the first argument on nodeDefinition,where did it get its' globalId? is Game and HidingSpot a name on the GraphQLSchema? What does this 'const {type, id} = fromGlobalId(globalId);' do? and also what is the 2nd argument? I need help understanding nodeDefinitions, somehow I can't find nodeDefinitions on the official documentation. Thank you.
If you were writing a GraphQL server without Relay, you'd define a number of entry points on the Query type, eg:
type Query {
picture(id: Int!): Picture
user(id: Int!): User
...etc
}
So when you want to get a User, you can easily get it because user is available as an entry point into the graph. When you build a query for your page/screen, it'll typically be several levels deep, you might go user -> followers -> pictures.
Sometimes you want to be able to refetch only part of your query, perhaps you're paginating over a connection, or you've run a mutation. What Relay's Node interface does is give you a standard way to fetch any type that implements it via a globally unique ID. Relay is capable of recognising such nodes in its queries, and will use them if possible to make refetching and paginating more efficient. We add the node type to the root Query type:
type Query {
picture(id: Int!): Picture
user(id: Int!): User
...etc
node(id: ID!): Node
}
Now for nodeDefinitions. Essentially this function lets us define two things:
How to return an object given its globalId.
How to return a type given an object.
The first is used to take the ID argument of the node field and use it to resolve an object. The second allows your GraphQL server to work out which type of object was returned - this is necessary in order for us to be able to define fragments on specific types when querying node, so that we can actually get the data we want. Without this, we couldn't be able to successfully execute a query such as this:
query Test {
node(id: 'something') {
...fragment on Picture {
url
}
...fragment on User {
username
}
}
}
Relay uses global object identification, which means, in my understanding, if your application ever try to search for an object. In your example, try to look for a game, or try to look for a hidingSpot. Relay will try to fetches objects in the standard node interface. i.e. find by {id: 123} of the Game, or find by {id:abc} of the hidingSpot. If your schema (Game, HidingSpot) doesn't set up the node interface, Relay will not be able to fetch an object.
Therefore, if your application requires a search in a "Game", in the schema, you need to define the node interfaces.
By using graphql-relay helper, use nodeDefinitions function only once in your application to basically map globally defined Ids into actual data objects and their GraphQL types.
The first argument receives the globalId, we map the globalId into its corresponding data object. And the globalId can actually be used to read the type of the object using fromGlobalId function.
The second function receives the result object and Relay uses that to map an object to its GraphQL data type. So if the object is an instance of Game, it will return gameType, etc.
Hope it will help you understand. I am on my way learning, too.
I'm not a programming savvy person, so please bear with me.
I've read blog entries and docs about command object. I've never used it and was wondering if I should. (I probably should...)
My project requires parsing, sorting, calculating, and saving results into database when users upload files.
So according to one of the blog entries I read and its corresponding github code,
1) SERVICE should receive file uploads, parse uploaded files (mainly docs and pdfs), sort parsed data using RegEx, and calculate data,
2) COMMAND OBJECT should call SERVICE, collect results and send results back to controller, and save results into the database,
3) CONTROLLER should receive request from VIEW, get results from COMMAND OBJECT, and send results back to VIEW.
Did I understand correctly?
Thanks.
I found this to be the best setup. Here is an example that I use on production:
Command Object (to carry data and ensure their validity):
#grails.validation.Validateable
class SearchCommand implements Serializable {
// search query
String s
// page
Integer page
static constraints = {
s nullable: true
page nullable: true
}
}
Controller (directs a request to a Service and then gets a response back from the Service and directs this response to a view):
class SomeController {
//inject service
def someService
def search(SearchCommand cmd) {
def result = someService.search(cmd)
// can access result in .gsp as ${result} or in other forms
render(view: "someView", model: [result: result])
}
}
Service (handles business logic and grabs data from Domain(s)):
class SomeService {
def search(SearchCommand cmd) {
if(cmd.hasErrors()) {
// errors found in cmd.errors
return
}
// do some logic for example calc offset from cmd.page
def result = Stuff.searchAll(cmd.s, offset, max)
return result
}
}
Domain (all database queries are handled here):
class Stuff {
String name
static constraints = {
name nullable: false, blank: false, size: 1..30
}
static searchAll(String searchQuery, int offset, int max) {
return Stuff.executeQuery("select s.name from Stuff s where s.name = :searchQuery ", [searchQuery: searchQuery, offset: offset, max:max])
}
}
Yes, you understood it correctly except the one thing: command object shouldn't save the data to DB - let service to do that. The other advantage of command object is data binding and validation of data from the client. Read more about command objects here grails command object docs
You can also find helpful information regarding your question in this article
grails best practices
I guess not. Its not really related to whether the save is done in a service it should always attempt to carry out complex stuff and specifically db stuff in a service. so that is regardless. I tend to not use command object but have got hooked on helper classes aka beans that sit in src/main/groovy and do all of the validation and formatting. I just did a form and in it has feedback and reason.
Initially I thought I would get away with
def someAction(String feedback, String reason) {
someService.doSomething(feedback,reason)
}
But then I looked closed and my form was firstly a textarea then the selection objects were bytes so above was not working and to simply fix it without adding the complexity to my controller/service I did this:
packe some.package
import grails.validation.Validateable
class SomeBean implements Validateable {
User user
byte reason
String feedback
static constraints = {
user(nullable: true)
reason(nullable:true, inList:UsersRemoved.REASONS)
feedback(nullable:true)
}
void setReason(String t) {
reason=t as byte
}
void setFeedback(String t) {
feedback=t?.trim()
}
}
Now my controller
class SomeController {
def userService
def someService
def doSomething(SomeBean bean){
bean.user = userService.currentUser
if (!bean.validate()) {
flash.message=bean.errors.allErrors.collect{g.message([error : it])}
render view: '/someTemplate', model: [instance: bean,template:'/some/template']
return
}
someService.doSomeThing(bean)
}
}
Now my service
Class SomeService {
def doSomeThing(SomeBean bean) {
if (bean.user=='A') {
.....
}
}
All of that validation would have still had to have been done somewhere, you say no validation but in a good model you should do validation and set things to be stored in proper structures to reduce overloading your db over time. difficult to explain but in short i am talking about your domain class objects and ensuring you are not setting up String something string somethingelse and then not even defining their lenghts etc. be strict and validate
if you have a text area this will be stored in the back end - so you will need to trim it like above - you will need to ensure the input does not exceed the max character of the actual db structure which if not defined will probably be 255
and by doing
static constraints = {
user(nullable: true)
reason(min:1, max:255, nullable:true, inList:UsersRemoved.REASONS)
Has already invalidated it through the bean.validate() in the controller if the user exceeded somehow my front end checks and put in more than 255.
This stuff takes time be patient
Edited to finally add in that example byte - is one to be careful of -
When adding any String or what ever I have started to define the specific like this and in the case of byte if it is a boolean true false - fine if not then define it as a tinyint
static mapping = {
//since there is more than 1 type in this case
reason(sqlType:'tinyint(1)')
feedback(sqlType:'varchar(1000)')
// name(sqlType:'varchar(70)')
}
If you then look at your tables created in the db you should find they have been created as per definition rather than standard 255 varchar which I think is the default for a declared String.
During writing validation rules a came across the problem that I need some content from a rule in my grammar which is hierarchically higher than the one I pass to my validationMethod.
I know that I can refer to a "higher" rule with .eContainer but then I don't have a clue how to access the values I want to.
For example I have the following grammar snippet:
rule1:
name=ID content=rule2
;
rule2:
<<whatever content>>
;
If I have a normal validationMethod with the argument rule1 then I can access the name via .name but when I give rule2 as an argument and then referring to rule via .eConatiner the .name method does not exist.
Greetings Krzmbrzl
EObject is the root class of all AST node classes. It comes from the EMF Ecore framework which is used by Xtext to generate the AST implementation. Therefore, the EObject class contains a lot of the tree structure features, e.g., iterating through a tree. The EObject.eContainer() method returns an element of type EObject which actually is the super type of the type of the actual returned object. To get access to methods of the next higher element, you have to cast the eContainers methods result like this:
#Check
public void check(rule2 r2) {
EObject o = r2.eContainer();
rule1 r1 = (rule1) o;
String r1Name = r1.getName();
}
If the type of the parent object is ambigous, you should test whether the actual type is the expected with an instanceof expression:
#Check
public void check(rule2 r2) {
EObject o = r2.eContainer();
if (o instanceof rule1) {
rule1 r1 = (rule1) o;
String r1Name = r1.getName();
}
}
Xtend provide the same instanceof-expression like Java. But if the object to be checked definetly can have more then a few types, you can use Xtends really powerful switch expression. It supports so called type guards. You can switch over any object and instead of case value: guards simply write the a concrete type:
switch (anyAbstractTypeObject) {
ConcreteSubtypeA: {...}
ConcreteSubtypeB: {...}
}
This is an elegant shorthand if-instanceof-eleseif-... in Xtend.
I messed around with this a bit yesterday and failed miserably. I want to convert:
"/$controller/$action?/$id?"
To
#in psudo
"/$controller/$id?/$action?"
#ideal regex
"\/(\w+)(\/\d+)?(\/\w+)?"
The most obvious way failed "/$controller/$action?/$id?"
I can write the regex's to do it, but I am having trouble finding a way to using true regexs (I found RegexUrlMapping but could not find out how to use it), and also can't find documentation on how to assign a group to a variable.
My question is 2 parts:
How to I define a URL Resource with a true regex.
How to I bind a "group" to a variable. In other words if I define a regex, how do I bind it to a variable like $controller, $id, $action
I would also like to be able to support the .json notation /user/id.json
Other things I have tried, which I thought would work:
"/$controller$id?$action?"{
constraints {
controller(matches:/\w+/)
id(matches:/\/\d+/)
action(matches:/\/\w+/)
}
}
also tried:
"/$controller/$id?/$action?"{
constraints {
controller(matches:/\w+/)
id(matches:/\d+/)
action(matches:/\w+/)
}
}
The grails way to deal with this is to set
grails.mime.file.extensions = true
in Config.groovy. This will cause Grails to strip off the file extension before applying the URL mappings, but make it available for use by withFormat
def someAction() {
withFormat {
json {
render ([message:"hello"] as JSON)
}
xml {
render(contentType:'text/xml') {
//...
}
}
}
For this you'd just need a URL mapping of "$controller/$id?/$action?"
I'm not aware of any way to use regular expressions in the way you want in the URL mappings, but you could get a forward mapping working using the fact that you can specify closures for parameter values that get evaluated at runtime with access to the other params:
"$controller/$a?/$b?" {
action = { params.b ?: params.a }
id = { params.b ? params.a : null }
}
which says "if b is set then use that as the action and a as the id, otherwise use a as the action and set id to null". But this wouldn't give you a nice reverse mapping, i.e. createLink(controller:'foo', action:'bar', id:1) wouldn't generate anything sensible, you'd have to use createLink(controller:'foo', params:[a:1, b:'bar'])
Edit
A third possibility you could try is to combine the
"/$controller/$id/$action"{
constraints {
controller(matches:/\w+/)
id(matches:/\d+/)
action(matches:/\w+/)
}
}
mapping with a complementary
"/$controller/$action?"{
constraints {
controller(matches:/\w+/)
action(matches:/(?!\d+$)\w+/)
}
}
using negative lookahead to ensure the two mappings are disjoint.