使用 Sequelize 的 INSERT 和 UPDATE 查询中的意外顺序

Question

First of all, I will explain briefly what I'm trying to do and models associated.

Having an array of trackingIds (10 elements), create a Chromosome with this trackingId and a "free" Palette

Considering:

Project.hasMany(models.Palette);
Project.hasMany(models.Chromosome);
Chromosome.hasOne(models.Palette);
Palette.belongsTo(models.Project, {foreignKey: 'projectId', as: 'project'});
Palette.belongsTo(models.Chromosome, {foreignKey: 'chromosomeId', as: 'chromosome'});

Now, my code looks something like this:

freeTrackingIds.forEach(async (trackingId) => {
    // Since the project has many palettes, I want to assign to the chromosome one palette that is free (this means, that has not been assigned to any chromosome yet).
    // I tried to reload() the project to fetch the changes in its palettes in previous iterations
    const availablePalettes = (await project.reload()).palettes.filter((palette) => !palette.chromosomeId);

    // Choosing a random palette from my available palettes. Yes, there might be better ways to achieve this. 
    const randomPalette = availablePalettes[Math.floor(Math.random() * availablePalettes.length)];

    // Creating the new chromosome for the project with the trackingId 
    const chromosome = await Chromosome.create({ projectId: project.id, trackingId: trackingId });

    // Linking the Palette to the chromosome
    randomPalette.chromosomeId = chromosome.id;
    await randomPalette.save();
  });

I have noticed that availablePalettes sentence would retrieve me palettes that were assigned in previous iterations of this forEach (that's why I decided to reload the project entity each time).

Even then reloading the project (that return with its free available palettes) I have experienced this. Checking my logs I noticed that:

Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): INSERT INTO "Chromosomes" ("id","trackingId","elements","timesRequested","generation","createdAt","updatedAt","projectId") VALUES (DEFAULT,$1,$2,$3,$4,$5,$6,$7) RETURNING *;
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3
Executing (default): UPDATE "Palettes" SET "chromosomeId"=$1,"updatedAt"=$2 WHERE "id" = $3

I'm not sure if this is exactly time-based but it looks like sequelize (due to performance reasons, surely) is doing all my chromosome creations before my palletes assignations. Could this be the reason why availablePalettes is returning palettes that were assigned to Chromosomes in previous iterations of this forEach()?

That's all for now, thank you in advance!

Answer 1

forEach func of an Array object does not support async syntax. Use 'for of':

forof (const trackingId of freeTrackingIds) {
// Since the project has many palettes, I want to assign to the chromosome one palette that is free (this means, that has not been assigned to any chromosome yet).
    // I tried to reload() the project to fetch the changes in its palettes in previous iterations
    const availablePalettes = (await project.reload()).palettes.filter((palette) => !palette.chromosomeId);

    // Choosing a random palette from my available palettes. Yes, there might be better ways to achieve this. 
    const randomPalette = availablePalettes[Math.floor(Math.random() * availablePalettes.length)];

    // Creating the new chromosome for the project with the trackingId 
    const chromosome = await Chromosome.create({ projectId: project.id, trackingId: trackingId });

    // Linking the Palette to the chromosome
    randomPalette.chromosomeId = chromosome.id;
    await randomPalette.save();  
}

Also I recommend you to use transaction for such batch operations.