Pipeline Terminator - Write Back

In this section, we’ll explore how to use write back terminators in Pipeline. We’ll use items model for this example.

GML

var schema = {
    id: {
        type: NIMBUSDB_DATA_TYPE.INTEGER,
        const: NIMBUSDB_CONSTRAINT.PRIMARY_KEY
    },
    name: NIMBUSDB_DATA_TYPE.STRING,
    price: {
        type: NIMBUSDB_DATA_TYPE.NUMBER,
        validator: function(data, value) {
            return value >= 0;
        },
        default_value: 0
    },
    is_locked: {
        type: NIMBUSDB_DATA_TYPE.BOOLEAN,
        const: NIMBUSDB_CONSTRAINT.OPTIONAL,
        default_value: false
    }
};

items = new NimbusDBModel("global", "items", schema, [
    { id: 1, name: "Apple", price: 5 },
    { id: 2, name: "Banana", price: 7.2 },
    { id: 3, name: "Cherry", price: 15 },
    { id: 4, name: "Date", price: 12.5 },
    { id: 5, name: "Elderberry", price: 8 },
    { id: 6, name: "Fig", price: 10 },
    { id: 7, name: "Grape", price: 6 },
    { id: 8, name: "Honeydew", price: 9 },
    { id: 9, name: "Kiwi", price: 4 },
    { id: 10, name: "Lemon", price: 3 }
]);

Writing Back to the Model

You can also update/replace the data in the model using the commit terminator.

Commit Array of Objects Object

The commit terminator commits the pipeline result back to the model.

GML

var items_pl = items.pipe().isolate()
    // let's say, we want to update the `price` and `is_locked` fields
    // for items with `price` greater than or equal to 8
    .filter(function(data, index) {         // include only items with `price` greater than or equal to 8
        return data.price >= 8;
    })
    .pluck(["id", "price", "is_locked"])    // pick the `id`, `price`, and `is_locked` fields
    .map(function(data, index) {            // map the result with the new values
        return { id: data.id, price: data.price * 0.8, is_locked: true };
    });

// result:
// [
//     { id: 3, price: 12.0, is_locked: true },
//     { id: 4, price: 10.0, is_locked: true },
//     { id: 5, price: 6.4, is_locked: true },
//     { id: 6, price: 8.0, is_locked: true },
//     { id: 8, price: 7.2, is_locked: true }
// ]

// print `items` model first, so we can see the changes
items.print();

// (1) "patch" mode, update the existing data
items_pl.commit();      // commit the result back to the model
items.print();          // print all the data in the model

// (2) "replace" mode, clear the existing data and insert the new data
items_pl.commit({ mode: "replace" });
items.print();          // print all the data in the model

---

References

Pipeline.commit()

Executes the pipeline and commits the result back to the model.

Overload 1

Signature

pipeline.d.ts

class NimbusDBPipeline {
    // ... other methods and properties ...
    static commit(
        _options?: NimbusDBPipelineCommitOptions
    ): void;
}

Parameters

_options

• Type: NimbusDBPipelineCommitOptions
• Default: undefined
• An optional object that allows you to customize the behavior of the commit operation.

Returns

• Type: void

Overload 2

Signature

pipeline.d.ts

class NimbusDBPipeline {
    // ... other methods and properties ...
    static commit(
        _pos: int,
        _options?: NimbusDBPipelineCommitOptions
    ): void;
}

Parameters

_pos

• Type: int
• The cursor position used as the end of the pipeline operations.

_options

• Type: NimbusDBPipelineCommitOptions
• Default: undefined
• An optional object that allows you to customize the behavior of the commit operation.

Returns

• Type: void

NimbusDBPipelineCommitOptions

Optional configurations for the commit terminator.

pipeline.d.ts

type NimbusDBPipelineCommitOptions = Partial<{
    mode: "patch" | "replace";      // patch = `.upsert`, replace = `.clear()` then `.insert()` (default = patch)
}>  & NimbusDBPipelineTerminalOptions
    & (NimbusDBInsertOptions | NimbusDBUpsertOptions)
;