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# Compute the preferred packages for the vetting requirements in the request

<div class="x2mdx-ref-page x2mdx-ref-page--operation x2mdx-ref-page--manual-api" />

<div class="x2mdx-ref-hero">
  <p class="x2mdx-ref-eyebrow">JSON Ledger API</p>

  <h1 class="x2mdx-ref-title">Compute the preferred packages for the vetting requirements in the request</h1>

  <div class="x2mdx-ref-badges">
    <span class="x2mdx-ref-badge x2mdx-ref-badge--protocol">OpenAPI</span>

    <span class="x2mdx-ref-badge x2mdx-ref-badge--added">Since 3.4</span>

    <span class="x2mdx-ref-badge x2mdx-ref-badge--changed">Changed 3.5</span>
  </div>
</div>

Compute the preferred packages for the vetting requirements in the request. A preferred package is the highest-versioned package for a provided package-name that is vetted by all the participants hosting the provided parties.

## Protocol Details

<div class="x2mdx-ref-meta-grid">
  <div class="x2mdx-ref-meta-item">
    <span class="x2mdx-ref-meta-label">Operation ID</span>
    <span class="x2mdx-ref-meta-value">postV2Interactive-submissionPreferred-packages</span>
  </div>

  <div class="x2mdx-ref-meta-item">
    <span class="x2mdx-ref-meta-label">Authentication</span>
    <span class="x2mdx-ref-meta-value">Bearer token</span>
  </div>

  <div class="x2mdx-ref-meta-item">
    <span class="x2mdx-ref-meta-label">Published</span>
    <span class="x2mdx-ref-meta-value">3.5</span>
  </div>
</div>

## Inputs

### Request body

<div class="x2mdx-ref-badges">
  <span class="x2mdx-ref-badge x2mdx-ref-badge--neutral">application/json</span>
</div>

<ParamField body="packageVettingRequirements" type="object[]" required>
  OpenAPI type: `PackageVettingRequirement[]`.

  The package-name vetting requirements for which the preferred packages should be resolved. Generally it is enough to provide the requirements for the intended command's root package-names. Additional package-name requirements can be provided when additional Daml transaction informees need to use package dependencies of the command's root packages. Required: must be non-empty
</ParamField>

<ParamField body="synchronizerId" type="string">
  The synchronizer whose vetting state should be used for resolving this query. If not specified, the vetting states of all synchronizers to which the participant is connected are used. Optional
</ParamField>

<ParamField body="vettingValidAt" type="string">
  The timestamp at which the package vetting validity should be computed on the latest topology snapshot as seen by the participant. If not provided, the participant's current clock time is used. Optional
</ParamField>

## Outputs

### 200

<div class="x2mdx-ref-badges">
  <span class="x2mdx-ref-badge x2mdx-ref-badge--neutral">application/json</span>
</div>

<ResponseField name="packageReferences" type="PackageReference[]" required>
  The package references of the preferred packages. Must contain one package reference for each requested package-name. If you build command submissions whose content depends on the returned preferred packages, then we recommend submitting the preferred package-ids in the `package_id_selection_preference` of the command submission to avoid race conditions with concurrent changes of the on-ledger package vetting state. Required: must be non-empty
</ResponseField>

<ResponseField name="synchronizerId" type="string" required>
  The synchronizer for which the package preferences are computed. If the synchronizer\_id was specified in the request, then it matches the request synchronizer\_id. Required
</ResponseField>

### 400

<div class="x2mdx-ref-badges">
  <span class="x2mdx-ref-badge x2mdx-ref-badge--neutral">text/plain</span>
</div>

<ResponseField name="value" type="string" required />

### default

<div class="x2mdx-ref-badges">
  <span class="x2mdx-ref-badge x2mdx-ref-badge--neutral">application/json</span>
</div>

<ResponseField name="code" type="string" required />

<ResponseField name="cause" type="string" required />

<ResponseField name="correlationId" type="string" />

<ResponseField name="traceId" type="string" />

<ResponseField name="context" type="Map_String" required />

<ResponseField name="resources" type="Tuple2_String_String[]" />

<ResponseField name="errorCategory" type="integer (int32)" required />

<ResponseField name="grpcCodeValue" type="integer (int32)" />

<ResponseField name="retryInfo" type="string" />

<ResponseField name="definiteAnswer" type="boolean" />

## History

<div class="x2mdx-ref-history" aria-label="Reference history">
  <div class="x2mdx-ref-history-event x2mdx-ref-history-event--changed">
    <div class="x2mdx-ref-history-event-head">
      <span class="x2mdx-ref-history-event-label">Changed</span>
      <code class="x2mdx-ref-history-event-version">3.5</code>
    </div>

    <p class="x2mdx-ref-history-event-detail">The POST /v2/interactive-submission/preferred-packages operation changed in this snapshot.</p>
  </div>

  <div class="x2mdx-ref-history-event x2mdx-ref-history-event--introduced">
    <div class="x2mdx-ref-history-event-head">
      <span class="x2mdx-ref-history-event-label">Introduced</span>
      <code class="x2mdx-ref-history-event-version">3.4</code>
    </div>
  </div>
</div>

<RequestExample>
  ```bash Request theme={null}
  curl --request POST \
    --url 'http://localhost:7575/v2/interactive-submission/preferred-packages' \
    --header 'Authorization: Bearer $TOKEN' \
    --header 'Content-Type: application/json' \
    --data '{"packageVettingRequirements":[{}],"synchronizerId":"string","vettingValidAt":"string"}'
  ```
</RequestExample>

<ResponseExample>
  ```json 200 response theme={null}
  {
    "packageReferences": [
      {}
    ],
    "synchronizerId": "string"
  }
  ```

  ```json default response theme={null}
  {
    "code": "string",
    "cause": "string",
    "correlationId": "string",
    "traceId": "string",
    "context": {},
    "resources": [
      [
        "string"
      ]
    ],
    "errorCategory": 0,
    "grpcCodeValue": 0,
    "retryInfo": "string",
    "definiteAnswer": false
  }
  ```
</ResponseExample>