Usage of transaction in Sails

[MaheshkumarSundaram]

Hi @neonexus,

I have a scenario in which I am performing three or more DB update operations using Sails Models.

These operations have to be atomic. Either all or nothing at all. So, I found .transaction().

Sample Usage:

module.exports = {
    friendlyName: '...',

    description: '..........',

    inputs: {
        name: {
            type: 'string',
            required: true,
            maxLength: 70,
        },
    },

    exits: {
        ok: {
            responseType: 'ok',
        },
        badRequest: {
            responseType: 'badRequest',
        },
        serverError: {
            responseType: 'serverError',
        },
    },

    fn: async (inputs, exits, env) => {
        const wfsName = inputs.name;

        // Start a database transaction
        await sails.models.wfsdoc.getDatastore().transaction(async (dbConn) => {
            try {
                const stagedwfs = await sails.models.wfsdoc.findOne({
                    where: { name: wfsName, version: 1 },
                    select: ['name', 'content', 'refDoc'],
                });

                if (!stagedwfs) {
                    return exits.ok({
                        success: false,
                        result: `No staged wfs with the name '${wfsName}' exists`,
                    });
                }

                const existingwfs = await sails.models.wfsdoc.findOne({
                    where: { name: wfsName, version: { '>': 1 } },
                    select: ['name', 'version', 'refDoc'],
                });

                if (existingwfs) {
                    if (existingwfs.version === 2) {
                        const refsUpdated = await sails.helpers.updateRefCountClnDoc(3, existingwfs.refDoc, dbConn);

                        if (refsUpdated !== true) {
                            throw new Error(refsUpdated);
                        }
                    }
                    await sails.models.wfsdoc
                        .destroyOne({
                            name: wfsName,
                            version: existingwfs.version,
                        })
                        .usingConnection(dbConn);
                }

                const refsUpdated = await sails.helpers.updateRefCountClnDoc(2, stagedwfs.refDoc, dbConn);

                if (refsUpdated !== true) {
                    throw new Error(refsUpdated);
                }

                await sails.models.wfsdoc
                    .updateOne({ name: wfsName, version: 1 })
                    .set({
                        version: 2,
                        user: null,
                    })
                    .usingConnection(dbConn);

                await dbConn.commit();

                return exits.ok();
            } catch (err) {
                if (dbConn) {
                    await dbConn.rollback();
                }
                return exits.serverError();
            }
        });
    },
};

I have used the .transaction() in my above code and it works fine as I have tested

But I wasn't sure whether there are any caveats in my usage. If you are aware of any issue with the above usage, kindly point them out.
Thanks.

[neonexus]

Because this is in a controller, instead of throwing errors, you more likely want to return exits.serverError();.

Past that I don't see anything.

[neonexus]

Scratch that, that is inside of a try / catch. Nevermind; carry on!

[MaheshkumarSundaram]

Thanks @neonexus