graphql: Allow user to define and pass arguments to fields.

[pawanrawal]

This would allow users to pass in arguments to fields of remote endpoints.

Fixes GRAPHQL-366

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[abhimanyusinghgaur]

Mostly looks good to me.
Just got a few queries.

Reviewable status: 0 of 7 files reviewed, 2 unresolved discussions (waiting on @abhimanyusinghgaur, @MichaelJCompton, and @pawanrawal)

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graphql/schema/custom_http_config_test.yaml, line 77 at r2 (raw file):

Quoted 6 lines of code…

    query {
      getCountry1(id: "0x1") {
        name
        code(first: 10, filter: {ids: "0x123", name: { eq: "github" }})
      }
    }

will this work too:

query ($first: Int) {
    getCountry1(id: "0x1") {
         name
         code(first: $first, filter: {ids: "0x123", name: { eq: "github" }})
    }
}

with $first: 10 ?

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graphql/schema/rules.go, line 635 at r2 (raw file):

}

func fieldArgumentCheck(typ *ast.Definition, field *ast.FieldDefinition) *gqlerror.Error {

For local types, the field arguments would be used only in case if the local type is being used with @custom, the field arguments can't be used with dgraph, right?
should we add a validation for this case too?

[pawanrawal]

Reviewed 7 of 7 files at r1.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @abhimanyusinghgaur and @MichaelJCompton)

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graphql/schema/custom_http_config_test.yaml, line 77 at r2 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

    query {
      getCountry1(id: "0x1") {
        name
        code(first: 10, filter: {ids: "0x123", name: { eq: "github" }})
      }
    }

will this work too:

query ($first: Int) {
    getCountry1(id: "0x1") {
         name
         code(first: $first, filter: {ids: "0x123", name: { eq: "github" }})
    }
}

with $first: 10 ?

Good point, this doesn't work right now for remote queries. I'll file this as a JIRA issue and handle separately. It requires propogating the variables defined in the original query and writing them to the remote query def along the variable values themselves.

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graphql/schema/rules.go, line 635 at r2 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

For local types, the field arguments would be used only in case if the local type is being used with @custom, the field arguments can't be used with dgraph, right?
should we add a validation for this case too?

Yeah, that is right for Dgraph types the arguments won't do anything if they are being used for Dgraph query. It is hard to add validation for that case because while validating a field within a type I don't really know if the type is being used as a return type for a custom query/field.

[abhimanyusinghgaur]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @MichaelJCompton)

[MichaelJCompton]

Add an e2e test with args.

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @pawanrawal)

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graphql/schema/wrappers.go, line 1959 at r2 (raw file):

	writer.WriteString("{\n")
	for i := 0; i < len(field.SelectionSet); i++ {
		// TODO - Check if this type conversion is safe.

I think fragments etc should be resolved to fields here ... so just remove this

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graphql/schema/testdata/schemagen/input/type-with-arguments-on-field.graphql, line 3 at r2 (raw file):

interface Abstract {
    id: ID!
    name(random: Int!, size: String): String!

Looks a bit strange, because this won't do anything, but I can see that it allows custom logic here.