express-cargo/dist/esm/binding.js

express middleware for class-based request parsing

import { CargoFieldError, CargoValidationError, CargoTransformFieldError } from './types';
import { CargoClassMetadata } from './metadata';
import { getCargoErrorHandler } from './errorHandler';
function getErrorKey(sourceKey, currentKey) {
    return sourceKey ? `${sourceKey}.${currentKey}` : currentKey;
}
function typeCasting(type, elementType, sourceKey, key, value, errors, sources, currentSource) {
    switch(type){
        case String:
            return String(value);
        case Number:
            {
                const parsedNumber = Number(value);
                if (isNaN(parsedNumber) || typeof value === 'string' && value.trim() === '') {
                    errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} must be a valid number`));
                    return undefined;
                }
                return parsedNumber;
            }
        case Boolean:
            return value === true || value === 'true';
        case Date:
            {
                const parsedDate = new Date(value);
                if (isNaN(parsedDate.getTime())) {
                    errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} must be a valid date`));
                    return undefined;
                }
                return parsedDate;
            }
        case Array:
            {
                if (!Array.isArray(value)) {
                    errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} must be an array`));
                    return undefined;
                }
                if (!elementType) return value;
                return value.map((element, i)=>typeCasting(elementType, undefined, sourceKey, `${key}[${i}]`, element, errors, sources, currentSource));
            }
        default:
            {
                const nextSources = {
                    ...sources,
                    [currentSource]: value
                };
                return bindObject(type, nextSources, errors, getErrorKey(sourceKey, key));
            }
    }
}
function bindObject(objectClass, sources, errors, sourceKey = '') {
    const metaClass = new CargoClassMetadata(objectClass.prototype);
    metaClass.markBindingCargoCalled();
    const targetObject = new objectClass();
    const fields = metaClass.getFieldList();
    const requestFields = metaClass.getRequestFieldList();
    const virtualFields = metaClass.getVirtualFieldList();
    // request transform
    for (const property of requestFields){
        const meta = metaClass.getFieldMetadata(property);
        if (!meta) continue;
        let value;
        const metaKey = meta.getKey();
        const key = typeof metaKey === 'string' ? metaKey : metaKey.description;
        if (!key) {
            errors.push(new CargoFieldError(getErrorKey(sourceKey, key), 'empty string or symbol is not allowed'));
            continue;
        }
        const requestTransformer = meta.getRequestTransformer();
        if (!requestTransformer) {
            errors.push(new CargoTransformFieldError(property, `${key} does not have transformer`));
            continue;
        }
        try {
            value = requestTransformer(sources.req);
            if (value === undefined || value === null) {
                if (meta.getDefault() !== undefined) {
                    targetObject[property] = meta.getDefault();
                    continue;
                } else if (meta.getOptional()) {
                    targetObject[property] = null;
                } else {
                    errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} is required`));
                }
            } else {
                targetObject[property] = value;
            }
            for (const rule of meta.getValidators()){
                const error = rule.validate(targetObject[property], targetObject);
                if (error) {
                    errors.push(error);
                }
            }
        } catch (error) {
            errors.push(new CargoTransformFieldError(property, `Error while computing request transform field: ${error instanceof Error ? error.message : String(error)}`));
        }
    }
    // source decorator parsing
    for (const property of fields){
        const meta = metaClass.getFieldMetadata(property);
        if (!meta) continue;
        let value;
        const metaKey = meta.getKey();
        const key = typeof metaKey === 'string' ? metaKey : metaKey.description;
        if (!key) {
            errors.push(new CargoFieldError(getErrorKey(sourceKey, key), 'empty string or symbol is not allowed'));
            continue;
        }
        const currentSource = meta.getSource();
        const currentSourceData = sources[currentSource];
        if (currentSourceData) {
            value = currentSourceData[key];
        }
        if (value === undefined || value === null) {
            if (meta.getDefault() !== undefined) {
                targetObject[property] = meta.getDefault();
                continue;
            } else if (meta.getOptional()) {
                targetObject[property] = null;
                continue;
            } else {
                errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} is required`));
                continue;
            }
        }
        if (meta.getEnumType() !== undefined) {
            targetObject[property] = value;
        } else {
            targetObject[property] = typeCasting(meta.type, meta.getArrayElementType(), sourceKey, key, value, errors, sources, currentSource);
        }
        const transformer = meta.getTransformer();
        if (transformer) {
            targetObject[property] = transformer(targetObject[property]);
        }
        for (const rule of meta.getValidators()){
            const error = rule.validate(targetObject[property], targetObject);
            if (error) {
                errors.push(error);
            }
        }
    }
    // virtual transform
    for (const property of virtualFields){
        const meta = metaClass.getFieldMetadata(property);
        if (!meta) continue;
        let value;
        const metaKey = meta.getKey();
        const key = typeof metaKey === 'string' ? metaKey : metaKey.description;
        if (!key) {
            errors.push(new CargoFieldError(getErrorKey(sourceKey, key), 'empty string or symbol is not allowed'));
            continue;
        }
        const virtualTransformer = meta.getVirtualTransformer();
        if (!virtualTransformer) {
            errors.push(new CargoTransformFieldError(property, `${key} does not have transformer`));
            continue;
        }
        try {
            value = virtualTransformer(targetObject);
            if (value === undefined || value === null) {
                if (meta.getDefault() !== undefined) {
                    targetObject[property] = meta.getDefault();
                    continue;
                } else if (meta.getOptional()) {
                    targetObject[property] = null;
                } else {
                    errors.push(new CargoFieldError(getErrorKey(sourceKey, key), `${key} is required`));
                }
            } else {
                targetObject[property] = value;
            }
            for (const rule of meta.getValidators()){
                const error = rule.validate(targetObject[property], targetObject);
                if (error) {
                    errors.push(error);
                }
            }
        } catch (error) {
            errors.push(new CargoTransformFieldError(property, `Error while computing virtual field: ${error instanceof Error ? error.message : String(error)}`));
        }
    }
    return targetObject;
}
export function bindingCargo(cargoClass) {
    return (req, res, next)=>{
        try {
            const errors = [];
            const sources = {
                req: req,
                body: req.body,
                query: req.query,
                params: req.params,
                header: req.headers,
                session: req.session
            };
            const cargo = bindObject(cargoClass, sources, errors);
            if (errors.length > 0) {
                throw new CargoValidationError(errors);
            }
            req._cargo = cargo;
            next();
        } catch (err) {
            if (err instanceof CargoValidationError) {
                const handler = getCargoErrorHandler();
                if (handler) {
                    return handler(err, req, res, next);
                }
            }
            next(err);
        }
    };
}
export function getCargo(req) {
    return req._cargo;
}