Extract custom scalars from GraphQL response - graphql

I defined some custom scalars in my GraphQL schema. If I query for data the custom scalars can be available on various places. Is it possible to extract them from a GraphQL response in a generic way?
So I get the response and then I want to extract all values of a scalar I defined into an array. Based on the schema the information is available. Is the some JavaScript library, which can do that?
I use Apollo Server and JavaScript on the client.

Use local resolver - #client directive - it can read other fields/cache to /collect/convert/provide required data.

Related

Graph QL , can we put response layout in a file and use the same file while calling a GraphQL query?

With GraphQL is it possible to define response layout in a file and use the same file while calling the GraphQL query? just to avoid too long request body.
I tried to use different string for request and response from java code. For very large request and response its quite difficult to handle from source.

Why does Relay set omitted optional variables to null?

When I execute a mutation created by useMutation with react-relay, and do not explicitly set optional variables, Relay sets those optional variables to null in the request.
My GraphQL server (Apollo) is able to distinguish between undefined and null values. I tested this by sending a GraphQL request from a HTTP client and omitting optional values.
I did search the docs, code and GitHub issues and neither did I find a way to adjust this behavior nor a reasoning why Relay does this.
The only thing I found is that in the official GraphQL specification omission and null are intermingled:
Mutations - Support being more specific about null and omission in input types
Questions:
What is Relay's reasoning behind setting missing optional variables to null? Is it because Relay adheres to the GraphQL spec accurately? If yes, does that mean that my Apollo GraphQL server is not properly adhering to the GraphQL spec?
Is there a way to omit optional variables instead of sending null with Relay?

How to derive values in apollo client

I have a few react components that mutate my server data and for now I have refetchQueries: [{query:myQuery}]. I need to restructured the data as a map for faster lookup time. How can I accomplish this? In Redux, I would have used reselect and in MobX I would have used #computed. As far as I can tell, apollo doesn't support this functionality yet.
I looked into:
#client directive, but this doesn't work for me since I have to compute the data on the server response.
reactive variables don't work either since I will have to change the variable everywhere I mutate the data, far from ideal.
There seems to be very little information out there about computed/derived values when using Apollo Client, the only reference I found was this one:
Apollo GraphQl Storing derived data
How about if you define in your schema & in your resolver some alternative (union) response structure? (not sure if this would work actually)
type Query{
books(mapBy:String): [Book]|JSON
}
so if you query (using it instead of mutation for simplicity)
query{
books(mapBy:"id")
}
it would return JSON
{
123: { __typename: "Book", name: "Dune"}
}
And if you don't want to return all of the Book fields in JSON, maybe pass extra param which would list actual structure you need.
Didn't encounter such problem myself yet, interesting. But otherwise, it should be done on client side.

How do I generate fragment types for apollo client?

I have an app written with reason-react using apollo-client. I have defined some fragments on the frontend to basically reuse some field definitions. I'm setting up automated tests for a components that uses fragments, but I keep getting this warning saying I need to use the IntrospectionFragmentMatcher.
'You are using the simple (heuristic) fragment matcher, but your queries contain union or interface types. Apollo Client will not be able to accurately map fragments. To make this error go away, use the `IntrospectionFragmentMatcher` as described in the docs: https://www.apollographql.com/docs/react/advanced/fragments.html#fragment-matcher'
I've tried setting up the fragment matcher according to the docs. The codegen result returns no types:
{
"__schema": {
"types": []
}
}
When I queried my server and looked at the manual method recommended by apollo-client, I noticed it would also return no types.
Another strange thing is that when I don't use the fragment matcher, I get the mocked response back but I just get the warnings from apollo. If I do use it then the mocked response doesn't return correctly.
Why would I query the graphql api for fragments defined in my frontend code? Why would I only received these errors when running the tests & using mock data, but not when running my actual application?
As the error states, the default fragment matcher does not work on intersection or union types. You will need to use Apollo's IntrospectionFragmentMatcher. It works by asking the server (introspecting) for information about your schema types, and then providing that information for reference to the cache so that it can match the fields accurately. It's not querying the server for information about the fragments you are defining on the front end, it's asking for data about the GraphQL schema that must be defined on your back end so that it can properly relate the two. There is an example in the documentation, also more information here.
As for why your server is not returning any types, that is a separate issue that would require more info to debug. If you're using Apollo Server, doublecheck your schema to make sure all the necessary types are defined properly and that you are passing them into the server when it's initialized.

How can I use isValidJSValue to validate a query variable in my client code?

I'm writing client-side code for an app that will query a GraphQL server. In a couple of places in my code, I'm passing around data that will eventually get turned into a query variable, so it needs to validate against a specific GraphQLInputType in my schema. On looking into some of the utilities that graphql-js provides, it looks like the isValidJSValue checker is exactly what I'm looking for, and its comments even mention that it's intended to be used to do just that.
The issue is that I don't have access to the GraphQL type I want to validate against as a JS object, which is what I'm pretty sure that function is looking for. I'm importing my schema (as an npm depdendency) as JSON, or I also have it in the schema notation. Is there some other utility I can use to get the JS type I need from one of those sources, and then use that to check my data with isValidJSValue? Or is there some other way I could go about this that I just haven't thought of?
You can use the JSON schema you have imported to construct an actual GraphQL schema instance using buildClientSchema here: https://github.com/graphql/graphql-js/blob/master/src/utilities/buildClientSchema.js
Then, it should be a simple matter of looking in the types field of the resulting schema to find your input type, and then calling isValidJSValue on it.
I'm curious, though - why validate the value on the client before sending it, rather than just relying on the validation the server will do?

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