KPC
Kevin Powell - Community•3mo ago
Ganesh

typescript error when flattenting a zoderror object

function flattenError(error: ZodError<z.ZodObject>) {
  const treefiedError = z.treeifyError(error);

  if (treefiedError.properties !== undefined) {
    const properties = treefiedError.properties;
    const flattenedError : Record<string, string> = {};

    for (const property in properties) {
      flattenedError[property] = properties[property]
    }
  }
}
function flattenError(error: ZodError<z.ZodObject>) {
  const treefiedError = z.treeifyError(error);

  if (treefiedError.properties !== undefined) {
    const properties = treefiedError.properties;
    const flattenedError : Record<string, string> = {};

    for (const property in properties) {
      flattenedError[property] = properties[property]
    }
  }
}
I have this code here. the error parameter after being passed to treeifyError would output value like this 
{
  "errors": [],
  "properties": {
    "name": {
      "errors": [
        "name must be at least 4 characters long",
      ],
    },
    "password": {
      "errors": [
        "password must be at least 8 characters long",
      ],
    },
    "passwordConfirm": {
      "errors": [
        "Too small: expected string to have >8 characters",
      ],
    },
  },
}
{
  "errors": [],
  "properties": {
    "name": {
      "errors": [
        "name must be at least 4 characters long",
      ],
    },
    "password": {
      "errors": [
        "password must be at least 8 characters long",
      ],
    },
    "passwordConfirm": {
      "errors": [
        "Too small: expected string to have >8 characters",
      ],
    },
  },
}
I wanted to flatten it into something like this 
{"password" : "password must be at least 8 characters long",
 "name" : "name must be at least 8 characters long"}
{"password" : "password must be at least 8 characters long",
 "name" : "name must be at least 8 characters long"}
but the typescript keeps complaining here and outputs a deeply nested type. Is there a way to make this easier to flatten?
No description
1 Reply
Ganesh
GaneshOP•3mo ago
by the way I did try flattenError method of zod but typescript marks it as deprecated 
export type $ZodErrorTree<T, U = string> = T extends [any, ...any[]] ? {
    errors: U[];
    items?: {
        [K in keyof T]?: $ZodErrorTree<T[K], U>;
    };
} : T extends any[] ? {
    errors: U[];
    items?: Array<$ZodErrorTree<T[number], U>>;
} : T extends object ? {
    errors: U[];
    properties?: {
        [K in keyof T]?: $ZodErrorTree<T[K], U>;
    };
} : {
    errors: U[];
};
export type $ZodErrorTree<T, U = string> = T extends [any, ...any[]] ? {
    errors: U[];
    items?: {
        [K in keyof T]?: $ZodErrorTree<T[K], U>;
    };
} : T extends any[] ? {
    errors: U[];
    items?: Array<$ZodErrorTree<T[number], U>>;
} : T extends object ? {
    errors: U[];
    properties?: {
        [K in keyof T]?: $ZodErrorTree<T[K], U>;
    };
} : {
    errors: U[];
};
I think this is the return type of treeifyError method is working with typescript always this complex or this is easy and I just don't know enough Honestly this ternary operator usage is disgusting 
function flattenError(error: ZodError<object>) {
    const treefiedError = z.treeifyError(error);

    if (treefiedError.properties !== undefined) {
        //assert properties type otherwise typescript will complain
        const properties = treefiedError.properties as Record<
            string,
            { errors: string[] }
        >;
        const flattenedError: Record<string, string> = {};

        for (const property in properties) {
            const errorMessages = properties[property]?.errors;
            if (errorMessages && errorMessages.length > 0) {
                flattenedError[property] = errorMessages[0]; 
            }
        }

        return flattenedError;
    } else {
        return {};
    }
}
function flattenError(error: ZodError<object>) {
    const treefiedError = z.treeifyError(error);

    if (treefiedError.properties !== undefined) {
        //assert properties type otherwise typescript will complain
        const properties = treefiedError.properties as Record<
            string,
            { errors: string[] }
        >;
        const flattenedError: Record<string, string> = {};

        for (const property in properties) {
            const errorMessages = properties[property]?.errors;
            if (errorMessages && errorMessages.length > 0) {
                flattenedError[property] = errorMessages[0]; 
            }
        }

        return flattenedError;
    } else {
        return {};
    }
}
this sorta works but i had to use assertation and object type

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