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Class: Parser

Resolver and function parser.

import { Parser } from '@appsync-butler/core';

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');

Extends​

Constructors​

new Parser()​

new Parser(optionsOrRoot): Parser

Parameters​

optionsOrRoot​

Path to VTL directory or parsing directives.

string | ParserOptions

Returns​

Parser

Overrides​

Reader.constructor

Properties​

structure​

protected readonly structure: object

functions​

functions: string

functionStructure​

functionStructure: object

functionStructure.description​

functionStructure.description: string

functionStructure.request​

functionStructure.request: string

functionStructure.response​

functionStructure.response: string

pipelineStructure​

pipelineStructure: object

pipelineStructure.after​

pipelineStructure.after: string

pipelineStructure.before​

pipelineStructure.before: string

pipelineStructure.pipeline​

pipelineStructure.pipeline: string

resolvers​

resolvers: string

root​

root: string

unitStructure​

unitStructure: object

unitStructure.request​

unitStructure.request: string

unitStructure.response​

unitStructure.response: string

Inherited from​

Reader.structure

Methods​

getFunctionPath()​

protected getFunctionPath(functionName): string

Parameters​

functionName​

string

Returns​

string

Inherited from​

Reader.getFunctionPath

getResolverPath()​

protected getResolverPath(typeName, fieldName): string

Parameters​

typeName​

string

fieldName​

string

Returns​

string

Inherited from​

Reader.getResolverPath

getVariable()​

getVariable(key): undefined | string

Retrieves the defined variable value.

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

Parameters​

key​

string

Variable identifier

Returns​

undefined | string

Variable value if set, undefined otherwise.

parseFunction()​

parseFunction(functionName): ParsedFunctionInfo

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

Parameters​

functionName​

string

Function name

Returns​

ParsedFunctionInfo

Parsed function information

parseResolver()​

parseResolver(typeName, fieldName): ParsedResolverInfo

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

Parameters​

typeName​

string

GraphQL type name

fieldName​

string

GraphQL field name

Returns​

ParsedResolverInfo

Parsed resolver information

path()​

protected path(...args): string

Parameters​

args​

...string[]

Returns​

string

Inherited from​

Reader.path

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​

typeName​

string

GraphQL type name

Returns​

string[]

A list of GraphQL fields

Inherited from​

Reader.readFields

readFunction()​

readFunction(functionName): FunctionInfo

Reads an AWS AppSync Function from disk.

Parameters​

functionName​

string

Function name

Returns​

FunctionInfo

Function information

Inherited from​

Reader.readFunction

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

readResolver()​

readResolver(typeName, fieldName): ResolverInfo

Reads a GraphQL field resolver from disk.

Parameters​

typeName​

string

GraphQL type name

fieldName​

string

GraphQL field name

Returns​

ResolverInfo

Unit or Pipeline Resolver information

Inherited from​

Reader.readResolver

readSubdirsSync()​

protected readSubdirsSync(dir, ignoreNoent): string[]

Parameters​

dir​

string

ignoreNoent​

boolean = false

Returns​

string[]

Inherited from​

Reader.readSubdirsSync

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

setVariable()​

setVariable(key, value): this

Sets an AppSync Butler variable for VTL file parsing. Usually, you would not call this method directory. Instead, specify your variables in LoaderOptions.variables

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​

key​

string

Variable identifier

value​

string

Value

Returns​

this