Typescript AST : How to get the asserted type?

Question

I am trying to parse a class and create default values of the property declarations that does not have values on the declaration.

For example from this:

class MyClass {
    name = 'My Class';
    id: string;
}

functionCall<MyClass>() // <-- I get the hold of the type class here

I want to generate something like this:

{
  name: 'My Class',
  id: 'I am generated'
}

I get MyClass from functionCall<MyClass> as type: ts.InterfaceType node and from there I parse the properties:

const typeChecker = program.getTypeChecker();
const type = typeChecker.getTypeAtLocation(callExpression); // This is the node where `functioCall<MyClass>()` is

type.getProperties().forEach(symbol => {
 // I am stuck here
});

The problem I have there, is that some symbols have symbol.valueDeclaration as undefined and I do not know what to use to know

1. The type of the property
2. If an assignment is done.

I though check if a symbol.valueDeclaration exist and if their symbol.valueDeclaration.kind is some keyword (like SyntaxKind.StringKeyword) but it would not work for something like

class SomeClass {
  noKeyword; // probably any?
}

Any help or pointers would be appreciated.

Answer 1

I was almost there, I needed to check if in the children of the valueDeclaration a literal was defined

  const propertyDeclaration = symbol.valueDeclaration;
  if (ts.isPropertyDeclaration(propertyDeclaration)) {
    const children = propertyDeclaration.getChildren();

    const assignationLiteral = children.find(child => {
      ts.isLiteralTypeNode;
      return [
        ts.SyntaxKind.NumericLiteral,
        ts.SyntaxKind.StringLiteral,
        ts.SyntaxKind.ObjectLiteralExpression,
      ].includes(child.kind);
    });

    if (assignationLiteral) {
      // A value es defined!
    } {
      // I have a keyword, I have to check which one is it :)
    }
}