Class: Parser

Resolver and function parser.

import { Parser } from 'aws-appsync-butler';

const parser = new Parser();
parser.readTypes(); // ['Query', 'Mutation', 'Post']
parser.readFields('Query'); // ['getPost', 'getAuthor']
const resolver = parser.parseResolver('Query', 'getPost');

parser.readFunctions(); // ['getPostById', 'getAuthorByPostId']
const func = reader.parseFunction('getPostById');

Hierarchy

• Reader

  ↳ Parser

Constructors

constructor

• new Parser(optionsOrRoot?)

Parameters

Name	Type	Description
optionsOrRoot	string | ParserOptions	Path to VTL directory or parsing directives.

Overrides

Reader.constructor

Methods

setVariable

▸ setVariable(key, value): Parser

Sets an in-memory variable for VTL file parsing.

vtl/resolvers/Mutation/addPost/request.vtl

#set($postId = $util.autoId())

{
    "version" : "2018-05-29",
    "operation" : "BatchPutItem",
    "tables": {
        "{{ tableName }}": [
            {
                "pk": $util.dynamodb.toDynamoDBJson("p-$postId"),
                "sk": $util.dynamodb.toDynamoDBJson("A"),
                "postTitle": $util.dynamodb.toDynamoDBJson($ctx.args.postInput.title),
                "postContent": $util.dynamodb.toDynamoDBJson($ctx.args.postInput.content)
            },
            {
                "pk": $util.dynamodb.toDynamoDBJson("u-$ctx.identity.sub"),
                "sk": $util.dynamodb.toDynamoDBJson("p-$postId")
            }
        ]
    }
}

parser.setVariable("tableName", dynamodbTable.tableName);
const resolver = parser.parseResolver('Mutation', 'addPost');

Parameters

Name	Type	Description
key	string	Variable identifier
value	string	Value

Returns

Parser

---

getVariable

▸ getVariable(key): undefined | string

Retrieves the defined variable value.

parser.setVariable('name', 'Ali');
parser.getVariable('name'); // 'Ali'

Parameters

Name	Type	Description
key	string	Variable identifier

Returns

undefined | string

Variable value if set, undefined otherwise.

---

parseResolver

▸ parseResolver(typeName, fieldName): ParsedResolverInfo

Parses Resolver files including variable substitution in mapping templates, pipeline sequence defintion parsing, and data source binding.

Parameters

Name	Type	Description
typeName	string	GraphQL type name
fieldName	string	GraphQL field name

Returns

ParsedResolverInfo

Parsed resolver information

---

parseFunction

▸ parseFunction(functionName): ParsedFunctionInfo

Parses function files including variable substitution in mapping templates and data source binding.

Parameters

Name	Type	Description
functionName	string	Function name

Returns

ParsedFunctionInfo

Parsed function information

---

readFunctions

▸ readFunctions(): string[]

Reads the on-disk function directory names. Essentially, the first-level subdirectories of functions are read.

vtl
├── functions
│   └── GetPostById
│       ├── request.vtl
│       └── response.vtl
└── resolvers

reader.readFunctions(); // ['GetPostById']

Returns

string[]

A list of function names

Inherited from

Reader.readFunctions

---

readTypes

▸ readTypes(): string[]

Reads the on-disk GraphQL type names. Essentially, the first-level subdirectories of resolvers are read.

vtl
├── functions
└── resolvers
    ├── Mutation
    └── Query
    └── Post

reader.readTypes(); // ['Mutation', 'Query', 'Post']

Returns

string[]

A list of GraphQL types

Inherited from

Reader.readTypes

---

readFields

▸ readFields(typeName): string[]

Reads the on-disk GraphQL field names. Essentially, the second-level subdirectories of resolvers are read.

vtl
├── functions
└── resolvers
    ├── Mutation
    └── Query
        └── getPost
            ├── request.vtl
            └── response.vtl

reader.readFields('Query'); // ['getPost']

Parameters

Name	Type	Description
typeName	string	GraphQL type name

Returns

string[]

A list of GraphQL fields

Inherited from

Reader.readFields

---

readResolver

▸ readResolver(typeName, fieldName): ResolverInfo

Reads a GraphQL field resolver from disk.

Parameters

Name	Type	Description
typeName	string	GraphQL type name
fieldName	string	GraphQL field name

Returns

ResolverInfo

Unit or Pipeline Resolver information

Inherited from

Reader.readResolver

---

readFunction

▸ readFunction(functionName): FunctionInfo

Reads an AWS AppSync Function from disk.

Parameters

Name	Type	Description
functionName	string	Function name

Returns

FunctionInfo

Function information

Inherited from

Reader.readFunction