Data Services API¶

using System.Net.Http.Headers;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Web;

public class DataServicesClient
{
    private readonly HttpClient _http;
    private readonly string _baseUrl;

    public DataServicesClient(string server, string bearerToken)
    {
        _baseUrl = $"https://{server}/api/dataservices";
        _http = new HttpClient();
        _http.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("Bearer", bearerToken);
        _http.DefaultRequestHeaders.Accept.Add(
            new MediaTypeWithQualityHeaderValue("application/json"));
    }

    public async Task<ODataResponse<T>> QueryAsync<T>(
        string viewName,
        string? filter = null,
        string? select = null,
        string? orderby = null,
        int? top = null,
        int? skip = null,
        bool count = false)
    {
        var query = HttpUtility.ParseQueryString(string.Empty);

        if (filter  is not null) query["$filter"]  = filter;
        if (select  is not null) query["$select"]  = select;
        if (orderby is not null) query["$orderby"] = orderby;
        if (top     is not null) query["$top"]     = top.ToString();
        if (skip    is not null) query["$skip"]    = skip.ToString();
        if (count)               query["$count"]   = "true";

        var url = $"{_baseUrl}/{viewName}?{query}";

        var response = await _http.GetAsync(url);
        response.EnsureSuccessStatusCode();

        var json = await response.Content.ReadAsStringAsync();
        return JsonSerializer.Deserialize<ODataResponse<T>>(json,
            new JsonSerializerOptions { PropertyNameCaseInsensitive = true })!;
    }
}

// OData response envelope
public class ODataResponse<T>
{
    [JsonPropertyName("@odata.count")]
    public int? Count { get; set; }

    [JsonPropertyName("value")]
    public List<T> Value { get; set; } = new();
}

// Customer record DTO
public class CustomerRecord
{
    [JsonPropertyName("customer_id")]
    public string CustomerId { get; set; } = string.Empty;

    [JsonPropertyName("customer_name")]
    public string CustomerName { get; set; } = string.Empty;

    [JsonPropertyName("phone")]
    public string? Phone { get; set; }

    [JsonPropertyName("date_last_modified")]
    public DateTime? DateLastModified { get; set; }
}

var ds = new DataServicesClient("p21-prod.yourcompany.com", bearerToken);

var result = await ds.QueryAsync<CustomerRecord>(
    viewName: "p21_view_customer",
    filter:   "company_id eq '01' and status eq 'A'",
    select:   "customer_id,customer_name,phone,date_last_modified",
    orderby:  "customer_name asc",
    top:      100,
    count:    true
);

Console.WriteLine($"Total matching customers: {result.Count}");
foreach (var customer in result.Value)
{
    Console.WriteLine($"{customer.CustomerId}: {customer.CustomerName}");
}

public async Task<List<T>> GetAllAsync<T>(
    DataServicesClient client,
    string viewName,
    string? filter = null,
    string? select = null,
    string orderby = "rowid asc",
    int pageSize = 200)
{
    var all = new List<T>();
    int skip = 0;

    while (true)
    {
        var page = await client.QueryAsync<T>(
            viewName:  viewName,
            filter:    filter,
            select:    select,
            orderby:   orderby,
            top:       pageSize,
            skip:      skip);

        all.AddRange(page.Value);

        if (page.Value.Count < pageSize) break;

        skip += pageSize;
    }

    return all;
}