Imports

Todo: fix syntax

GraphQL specification does not yet provide a way of importing types from SDL from other sources. There is some discussion on this topic but nothing concrete and "official" is yet released.

graphql-import solves this with a JS style syntax

Tanka GraphQL solves this by providing a similar syntax to graphql-import but not implementing it fully.

Syntax

Syntax of the import requires providing a keyword, optional type filters and the location from which to import. Location does not need to be a file system. Imports need to be wrapped into block string and need to be at the beginning of the document.

Example: import all types from "/query"

"""
tanka_import from "/query"
"""

Example: import Person from "/types/Person"

"""
tanka_import Person from "/types/Person"
"""

Example: import Person, Pet from "/types/Person"

"""
tanka_import Person, Pet from "/types/Person"
"""

Providers

Parser.ParseDocumentAsync allows providing ParserOptions which allows setting a list of import providers. Parser will query these providers when it finds the tanka_import-keyword. Provider can tell the parser that it can complete the import by returning true from CanImport function. If multiple providers can import the import then the parser will pick the first one.

Built in providers: (these are added to options by default)

• ExtensionsImportProvider: provides Tanka GraphQL extension types,
• FileSystemImportProvider: import types from files,
• EmbeddedResourceImportProvider: import types from EmbeddedResources.

Custom providers can be implemented by implementing IImportProvider interface and adding the provider to the options.

Imports are only supported when using the SchemaBuilder.SdlAsync extension method or Parser.ParseDocumentAsync

ExtensionsImportProvider

This import provider allows importing Tanka GraphQL extensions. Currently these extensions only include:

• [cost-analysis][]: @cost directive.

Syntax

"""
tanka_import from "tanka://<extension>"
"""

FileSystemImportProvider

This import provider allows importing files. These files are parsed using the same parser options as the main file and can also contain other imports.

Syntax

"""
tanka_import from "path/to/file"
"""

If no file extension provided then ".graphql" will be appended to the path.

Example []

        [Fact]
        public async Task Parse_Sdl()
        {
            /* Given */
            var sdl =
                  @"
                    """"""
                    tanka_import from ""Files/Import""
                    """"""

                    type Query {
                        imported: ImportedType
                    }
                 ";

            /* When */
            var builder = await new SchemaBuilder()
                // BuiltIn import providers are used
                .SdlAsync(sdl);

            var schema = builder.Build();

            /* Then */
            var importedType = schema.GetNamedType<ObjectType>("ImportedType");
            Assert.NotNull(importedType);
            var importedField = schema.GetField(schema.Query.Name, "imported");
            Assert.Same(importedType, importedField.Type.Unwrap());
            var nestedType = schema.GetNamedType<ObjectType>("NestedObject");
            Assert.NotNull(nestedType);
        }

EmbeddedResourceImportProvider

This import provider allows importing files embedded into the assembly. These files are parsed using the same parser options as the main file and can also contain other imports.

Syntax

"""
tanka_import from "embedded://<assembly>/<resourceName>"
"""

Other Examples

See cost-analysis for example import from the TGQL extensions.