140 lines
3.6 KiB
Go
140 lines
3.6 KiB
Go
package generate
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import (
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"bytes"
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"fmt"
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"go/format"
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"path/filepath"
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"runtime"
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"strings"
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"text/template"
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"github.com/vektah/gqlparser/ast"
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"github.com/vektah/gqlparser/formatter"
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)
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// TODO: package template into the binary using one of those asset thingies
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var _, thisFilename, _, _ = runtime.Caller(0)
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var tmplRelFilename = "operation.go.tmpl"
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var tmplAbsFilename = filepath.Join(filepath.Dir(thisFilename), tmplRelFilename)
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var tmpl = template.Must(template.ParseFiles(tmplAbsFilename))
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type templateParams struct {
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// The name of the package into which to generate the operation-helpers.
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PackageName string
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// The list of operations for which to generate code.
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Operations []operation
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}
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type operation struct {
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// The type of the operation (query, mutation, or subscription).
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Type ast.Operation
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// The name of the operation, from GraphQL.
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Name string
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// The documentation for the operation, from GraphQL.
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Doc string
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// The body of the operation to send.
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Body string
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// The arguments to the operation.
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Args []argument
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// The type-name for the operation's response type.
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ResponseName string
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// The body of the operation's response type (e.g. struct { ... }).
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ResponseType string
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}
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type argument struct {
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GoName string
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GoType string
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GraphQLName string
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}
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func fromASTArg(arg *ast.VariableDefinition, schema *ast.Schema) argument {
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return argument{
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GraphQLName: arg.Variable,
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GoName: arg.Variable, // TODO: normalize this to go-style
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GoType: typeForInputType(arg.Type, schema),
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// TODO: figure out what to do about defaults
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}
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}
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func fromASTOperation(op *ast.OperationDefinition, schema *ast.Schema) (operation, error) {
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// TODO: we may have to actually get the precise query text, in case we
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// want to be hashing it or something like that. Although maybe
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// there's no reasonable way to do that with several queries in one
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// file.
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var builder strings.Builder
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f := formatter.NewFormatter(&builder)
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f.FormatQueryDocument(&ast.QueryDocument{
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Operations: ast.OperationList{op},
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// TODO: handle fragments
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})
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args := make([]argument, len(op.VariableDefinitions))
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for i, arg := range op.VariableDefinitions {
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args[i] = fromASTArg(arg, schema)
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}
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typ, err := typeForOperation(op, schema)
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if err != nil {
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return operation{}, fmt.Errorf("could not compute return-type for query: %v", err)
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}
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return operation{
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Type: op.Operation,
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Name: op.Name,
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// TODO: this is actually awkward, because GraphQL doesn't allow
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// for docstrings on queries (only schemas). So we have to extract
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// the comment, or omit doc-comments for now.
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Doc: "TODO",
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// The newline just makes it format a little nicer
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Body: "\n" + builder.String(),
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Args: args,
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// TODO: configure ResponseName format
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ResponseName: op.Name + "Response",
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ResponseType: typ,
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}, nil
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}
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func Generate(config *Config) ([]byte, error) {
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schema, err := getSchema(config.Schema)
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if err != nil {
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return nil, err
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}
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document, err := getAndValidateQueries(config.Queries, schema)
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if err != nil {
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return nil, err
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}
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operations := make([]operation, len(document.Operations))
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for i, op := range document.Operations {
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operations[i], err = fromASTOperation(op, schema)
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if err != nil {
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return nil, err
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}
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}
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data := templateParams{
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// TODO: configure PackageName
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PackageName: "example",
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Operations: operations,
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}
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var buf bytes.Buffer
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err = tmpl.Execute(&buf, data)
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if err != nil {
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return nil, fmt.Errorf("could not render template: %v", err)
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}
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formatted, err := format.Source(buf.Bytes())
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if err != nil {
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return nil, fmt.Errorf("could not gofmt template: %v", err)
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}
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return formatted, nil
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}
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