JSON parser that never throws

[Stadly]

When using json.isParse when data on the client, there is no guarantee that the data is valid JSON, since the user may have tampered with it. In such cases, json.isParse throws SyntaxError. This makes typia cumbersome to use, since I have to handle exceptions when all I want to know is whether the data parses to the correct type. When the data is not parsable it does not parse to the correct type, so I would expect the function to just return null in such cases.

This would be a breaking change, so I suggest either adding a parameter to isParse or creating a separate safeParse that returns null when an error is thrown.

For example:

export const safeParse = <Type>(input: string) => {
  try {
    return assertParse<Type>(input);
  } catch (error) {
    return null;
  }
};

I tried just making this helper function, but then I get a warning: [vite] warning: @rollup/plugin-typescript TS(typia.json.assertParse): non-specified generic argument. Seems like I can't use typia with generics?

[samchon]

You have to specify the generic argument.

Recommend to utilize the callback function in that case.

[Stadly]

Thanks for your reply, @samchon.

It makes sense that the generic argument must be specified.

What do you mean by the callback function? I can't find anything about callbacks in the documentation.

Also, which issue is this a duplicate of, since you added the duplicate label? I wasn't able to find any.

[samchon]

import typia, { tags } from "typia";

interface IMember {
  id: string & tags.Format<"uuid">;
  name: string;
  age: number &
    tags.Type<"uint32"> &
    tags.Minimum<20> &
    tags.ExclusiveMaximum<100>;
}

const safeParse = 
  <T>(parser: (input: string) => T) => 
  (str: string): T | null => {
    try {
      return parser(str);
    } catch {
      return null;
    }
  };

console.log(
  safeParse(
    typia.json.createAssertParse<IMember>(),
  )(
    typia.json.stringify(
      typia.random<IMember>(),
    ),
  ),
);

https://typia.io/playground/?script=JYWwDg9gTgLgBDAnmYBDANHA3g1BzAZzgF84AzKCEOAIiRVRoG4AoF4AOxgFMozUAxtzgBJALLcQAI17YWcOMAAmALjgEYUTnjgAyXIQB0AMWghUMADw0ArjeU0AfKwUdUIbmo1aOeF3HxPOA4baVldeQUDAkMAFWRua3suAGYAJic9SIUYfBixTlBQyzSABkcsqOjDAFEADwEAGxsCYAA3bjFUOqKQSwBGUvLWYjYBCA4NdVQybgAFVCgCYQBeOEjLWMcACjBF5ag1bc4wGxgvTW0ASjgVitibu-WFbe8LnzwrtVi4AB9gmyNRq3CpYbIIKCIORVBRQbgwGxQDhwPZLXivTRXfwKUgCCwCAAW0JhcIRSIBQOxJEixFYLHGkwgjW4hkaEDw20iBBm8323E5VXoaEMACsCBNDAI4RZuABBAgHGALNGWcSSGRQHZXdCRK4CqJC1Ci8UcQzebTAMiIfWC5DCqCoDhKKiqiRhTXbbXgr0KL1YoA

Here it is.

[Stadly]

Thanks!